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Examining the effect of intramammary infections with minor mastitis pathogens on the acquisition of new intramammary infections with major mastitis pathogens-A systematic review and meta-analysis
Abstract
Major mastitis pathogens such as Staphylococcus aureus, Streptococcus agalactiae, Streptococcus uberis, Streptococcus dysgalactiae, and the coliforms are usually considered more virulent and damaging to the udder than minor mastitis pathogens such as Corynebacterium bovis and coagulase-negative staphylococci (CNS). The current literature contains several studies detailing analyses with conflicting results as to whether intramammary infection (IMI) with the minor pathogens decreases, increases, or has no effect on the risk of a quarter acquiring a new intramammary infection (NIMI) with a major pathogen. To investigate the available scientific evidence regarding the effect of IMI with minor pathogens on the acquisition of NIMI with major pathogens, a systematic review and meta-analysis were conducted. The total extant English- and French-language literature in electronic databases was searched and all publications cited by relevant papers were investigated. Results from 68 studies were extracted from 38 relevant papers. Random-effects models were used to investigate the effects of CNS and C. bovis on acquisition of new IMI with any of the major pathogens, as well as individually for the minor pathogens and Staph. aureus. Significant heterogeneity among studies exists, some of which could be accounted for by using meta-regression. Overall, observational studies showed no effect, whereas challenge studies showed strong and significant protective effects, specifically when major pathogens were introduced into the mammary gland via methods bypassing the teat end. Underlying risk can account for several unmeasured factors, and studies with higher underlying risk found more protective effects of minor pathogens. Larger doses of challenge organisms reduced the protective effect of minor pathogens, and studies with more stringent diagnostic criteria for pathogen IMI identified less protection. Smaller studies (those utilizing fewer than 40 cows) also showed a greater protective effect than larger studies.
... For example, CNS IMI or teat apex colonization have long been considered to have a protective effect (Rainard and Poutrel, 1988;Matthews et al., 1991). However, a meta-analysis revealed that observational studies did not report a protective effect of pre-existing IMI with CNS (Reyher et al., 2012a). Furthermore, the presence of CNS increased the probability of a new Staphylococcus aureus IMI (Reyher et al., 2012b) and new IMI in the ipsilateral quarter (Reyher et al., 2013). ...
... Furthermore, the presence of CNS increased the probability of a new Staphylococcus aureus IMI (Reyher et al., 2012b) and new IMI in the ipsilateral quarter (Reyher et al., 2013). Overall, it has been proposed that any protective or negative effect of CNS on new IMI is probably species-dependent (Reyher et al., 2012a;Vanderhaeghen et al., 2014). The mechanisms behind the positive or negative effects of CNS have yet to be characterized. ...
... The effect of pre-existing CNS colonization on new infections is a major topic of discussion (Reyher et al., 2012a;Vanderhaeghen et al., 2014), and conflicting results have been reported on this effect. The exact nature of the observed effect with CNS is still unknown. ...
Coagulase-negative staphylococci (CNS) are considered to be commensal bacteria in humans and animals, but are now also recognized as etiological agents in several infections, including bovine mastitis. Biofilm formation appears to be an important factor in CNS pathogenicity. Furthermore, some researchers have proposed that CNS colonization of the intramammary environment has a protective effect against other pathogens. The mechanisms behind the protective effect of CNS have yet to be characterized. The aim of this study was to evaluate the effect of CNS isolates with a weak-biofilm phenotype on the biofilm formation of other staphylococcal isolates. We selected 10 CNS with a weak-biofilm phenotype and 30 staphylococcal isolates with a strong-biofilm phenotype for this study. We measured biofilm production by individual isolates using a standard polystyrene microtiter plate assay and compared the findings with biofilm produced in mixed cultures. We confirmed the results using confocal microscopy and a microfluidic system with low shear force. Four of the CNS isolates with a weak-biofilm phenotype (Staphylococcus chromogenes C and E and Staphylococcus simulans F and H) significantly reduced biofilm formation in approximately 80% of the staphylococcal species tested, including coagulase-positive Staphylococcus aureus. The 4 Staph. chromogenes and Staph. simulans isolates were also able to disperse pre-established biofilms, but to a lesser extent. We also performed a deferred antagonism assay and recorded the number of colony-forming units in the mixed-biofilm assays on differential or selective agar plates. Overall, CNS with a weak-biofilm phenotype did not inhibit the growth of isolates with a strong-biofilm phenotype. These results suggest that some CNS isolates can negatively affect the ability of other staphylococcal isolates and species to form biofilms via a mechanism that does not involve growth inhibition.
... Previous studies have clearly established that co-infections with other NAS and pathogens occur (113)(114)(115), yet there exists conflicting evidence as to whether NAS increase susceptibility to major pathogens such as S. aureus or prevent it from colonizing the udder. Because major pathogens are generally considered more virulent and damaging to the udder than minor mastitis pathogens such as NAS, it would be of interest to clarify what impact NAS has on major pathogens. ...
... The intensity of inhibition varied amongst target species, with only 2 out of 10 S. chromogenes isolates showing consistent inhibitory activity (117). A systematic review of the current literature revealed that strong protective effects were observed in studies that had higher underlying risks, as well as in challenge studies which introduced major pathogens into the udder through the teat end (113). Studies that used larger doses of challenge organisms and those with more stringent diagnostic criteria for pathogen IMI reported reduced protective effects. ...
Despite considerable efforts to control bovine mastitis and explain its causes, it remains the most costly and common disease of dairy cattle worldwide. The role and impact of non-aureus staphylococci (NAS) in udder health are not entirely understood. These Gram-positive bacteria have become the most frequently isolated group of bacteria in milk samples of dairy cows and are associated with (mild) clinical and subclinical mastitis. Different species and strains of NAS differ in their epidemiology, pathogenicity, virulence, ecology and host adaptation, and antimicrobial resistance profiles. They have distinct relationships with the microbiome composition of the udder and may also have protective effects against other mastitis pathogens. Some appear to persist on the skin and in the teat canal and udder, while others seem to be transient residents of the udder from the environment. Analyzing genotypic and phenotypic differences in individual species may also hold clues to why some appear more successful than others in colonizing the udder. Understanding species-level interactions within the microbiome and its interactions with host genetics will clarify the role of NAS in bovine mastitis and udder health.
... For most mastitis pathogens, the teat end is considered the porte d'entree into the mammary gland. It has been suggested that presence of minor pathogens (non-aureus staphylococci, corynebacteria) at the teat end may protect against infection with major pathogens (Reyher et al., 2012). The authors of a recent review (Reyher et al., 2012) concluded that observational studies showed no such effect, "whereas challenge studies showed strong and significant protective effects, specifically when major pathogens were introduced into the mammary gland via methods bypassing the teat end." ...
... It has been suggested that presence of minor pathogens (non-aureus staphylococci, corynebacteria) at the teat end may protect against infection with major pathogens (Reyher et al., 2012). The authors of a recent review (Reyher et al., 2012) concluded that observational studies showed no such effect, "whereas challenge studies showed strong and significant protective effects, specifically when major pathogens were introduced into the mammary gland via methods bypassing the teat end." Physical or physicochemical characteristics of the teat end may contribute to that discrepancy, such as the amount of keratin present, peak flow rate and teat canal length (Capuco et al., 1992;Lacy-Hulbert & Hillerton, 1995). ...
Environmental mastitis is the most common and costly form of mastitis in modern dairy herds where contagious transmission of intramammary pathogens is controlled through implementation of standard mastitis prevention programmes. Environmental mastitis can be caused by a wide range of bacterial species, and binary classification of species as contagious or environmental is misleading, particularly for Staphylococcus aureus, Streptococcus uberis and other streptococcal species, including Streptococcus agalactiae. Bovine faeces, the indoor environment and used pasture are major sources of mastitis pathogens, including Escherichia coli and S. uberis. A faeco-oral transmission cycle may perpetuate and amplify the presence of such pathogens, including Klebsiella pneumoniae and S. agalactiae. Because of societal pressure to reduce reliance on antimicrobials as tools for mastitis control, management of environmental mastitis will increasingly need to be based on prevention. This requires a reduction in environmental exposure through bedding, pasture and pre-milking management and enhancement of the host response to bacterial challenge. Efficacious vaccines are available to reduce the impact of coliform mastitis, but vaccine development for gram-positive mastitis has not progressed beyond the “promising” stage for decades. Improved diagnostic tools to identify causative agents and transmission patterns may contribute to targeted use of antimicrobials and intervention measures. The most important tool for improved uptake of known mastitis prevention measures is communication. Development of better technical or biological tools for management of environmental mastitis must be accompanied by development of appropriate incentives and communication strategies for farmers and veterinarians, who may be confronted with government-mandated antimicrobial use targets if voluntary reduction is not implemented.
... Streptococcus agalactiae (S. agalactiae) is a species of Grampositive chain-forming cocci, and is also called group B Streptococcus. It mainly affects humans (Lannes-Costa et al., 2021;Nguyen et al., 2021;Tavares et al., 2022), cattle (Keefe, 2012;Reyher et al., 2012;Kabelitz et al., 2021), and fish (Alazab et al., 2022;Piamsomboon et al., 2022;Sapugahawatte et al., 2022). In dairy animals, S. agalactiae invades the mammary gland, which can lead to clinical or subclinical mastitis; as a result, a reduction in milk production of > 20% is common (Keefe, 1997). ...
Streptococcus agalactiae infections may lead to clinical or subclinical mastitis in dairy animals when it invades the mammary gland. In this study, 51 S. agalactiae strains were isolated from 305 milk samples that were collected from goats with mastitis in 13 provinces of China. The antimicrobial resistance of S . agalactiae was determined by disk diffusion methods against 18 antibiotics from six classes. In addition, multilocus sequence typing (MLST), and the presence of resistance and virulence genes was determined by PCR analysis. Seven sequence types in five clonal complexes were identified according to MLST; CC103 and CC67 strains were predominant, with rates of 45.1% and 39.2%, respectively. All isolates (100%) were multiresistant to three or more antimicrobial agents. S . agalactiae isolates had a 100% resistance rate to penicillin, oxacillin, and amoxicillin, followed by doxycycline (82.4%), tetracycline (76.5%), and amikacin (74.5%). The lowest resistance was observed for ciprofloxacin (29.4%), which varied in five different regions. The detection rates of six classes of antimicrobial-related genes were calculated as follows: 33 (64.7%) for β-lactam-related resistance gene, 12 (23.5%) for tetracyclines, 11 (21.6%) for quinolone-related resistance genes, 10 (19.6%) for aminoglycosides, 7 (13.7%) for macrolides ( ermA , ermB , and mefA ), and 3 (5.9%) for lincosamide ( lnu(B) ). Regarding virulence genes, profile 1 ( bca cfb - cspA - cylE-hylB-bibA-pavA-fbsA-fbsB ) was the most prevalent, with a detection rate of 54.9%. This work provides a primary source related to the molecular epidemiology of S. agalactiae in dairy goat herds in China and will aid in the clinical treatment, prevention, and control of mastitis.
... 12 Among the NDC, C. bovis is frequently isolated from cow udder and milk 13 ; its role as a pathogen in clinical and subclinical mastitis remains under debate. 14,15 The increasing attention given to NDC as potential pathogens has been enabled by improvements in identification methods. 16,17 The sisal wool condition in sheep in Argentine Patagonia has been recognized since the 1990s, yet its underlying aetiology has remained unclear. ...
Background:
Sisal wool condition is a skin disease affecting Merino sheep in the Argentine Patagonia region. Corynebacterium spp. isolates have previously been isolated from skin swabs from lesions, while specific identification of the bacteria involved has not been reported.
Hypothesis/objectives:
The aim of this work was to characterize the bacterial agent isolated from sisal wool lesions and to develop a diagnostic method for field surveillance.
Materials and methods:
Molecular identification of a collection of 72 isolates obtained previously was performed using PCR and 16S rRNA and rpoB sequencing. A field survey was carried out on two farms in the Río Negro province of Argentine Patagonia. Swab samples from sheep with and without skin lesions were collected and analysed by PCR and culture.
Results:
Isolates analysed were confirmed by sequencing as Corynebacterium bovis. Using a PCR test without culture step, all field samples from affected sheep were positive for C. bovis; samples from the healthy skin from the same animals or clinically healthy sheep all were negative.
Conclusions and clinical relevance:
Sisal wool skin disease was associated with C. bovis infection based on culture and PCR methods; the latter may be useful for helping to pursue a disease control strategy.
... When the natural barrier fails, the pathogens enter the milk pool along the nipple ducts. As the bacteria multiply, the inflammatory cells in the mammary tissue also gradually increase, further aggravating the damage and the loss of structural integrity of the mammary acini [35,51,52]. To further understand the protective effect of artemisinin on E. coli-induced bovine mastitis, an E. coli-induced mastitis model in mice was established. ...
Bovine mastitis is an important disease affecting dairy farming, and it causes large economic losses to the dairy industry. Escherichia coli (E. coli) is considered to be a causative environmental pathogen and frequently enters into mammary glands, causing inflammation. Artemisinin is a highly effective malaria remedy and is not easy to develop drug resistance to. In recent years, other effects of artemisinin (including antitumor, anti-inflammatory, antifungal, etc.) have been increasingly discovered and applied. The current study aimed to investigate whether artemisinin could attenuate E. coli–induced inflammation. Through the E. coli mastitis model in MAC-T cells and mice, the protective effects of artemisinin were analyzed by CCK-8 (Cell Counting Kit-8), Western blot, and RT-qPCR. The results showed that artemisinin reversed the decrease of cell viability and upregulated TLR4 (toll-like receptor 4)/NF-κB (nuclear factor κB) and MAPK (mitogen activated protein kinase)/p38 signaling pathways, as well as restrained the expression of TNF-α, IL-6, and IL-1β mRNA caused by E. coli. Meanwhile, artemisinin also alleviated mammary tissue damage, reduced inflammatory cells’ infiltration, and decreased the levels of inflammatory factors in a mice mastitis model. This study demonstrated that artemisinin alleviated the inflammatory response of mouse mastitis and MAC-T cells induced by E. coli, thus providing a practical approach for the clinical control of mastitis.
... There are differences in the isolation rates of major mastitis pathogens and CNS in epidemiological studies on CNS. It is arguable whether the CNS has a synergistic or antagonistic effect on IMI caused by major mastitis pathogens [32][33][34]. Although DNase positivity 11.9%, mannitol positivity 66.6% were found of the total CNS in our study. ...
... bacteraemia, endocarditis and pneumonia (Lee et al., 2018). In animals, it is best known as a cause of mastitis in dairy cattle, being one of the major mastitis pathogens (Reyher et al., 2012;Rainard et al., 2018), of SSTI in various animal species, including horses (Devriese et al., 1985;Sieber et al., 2011), and of skin and skeletal disorders in poultry (Heidemann Olsen et al., 2018;Szafraniec et al., 2022). ...
Staphylococcus aureus (S. aureus) was identified among the most relevant antimicrobial-resistant (AMR) bacteria in the EU for cattle and horses in previous scientific opinions. Thus, it has been assessed according to the criteria of the Animal Health Law (AHL), in particular criteria of Article 7 on disease profile and impacts, Article 5 on its eligibility to be listed, Annex IV for its categorisation according to disease prevention and control rules as in Article 9, and Article 8 for listing animal species related to the bacterium. The assessment has been performed following a methodology previously published. The outcome is the median of the probability ranges provided by the experts, which indicates whether each criterion is fulfilled (lower bound ≥ 66%) or not (upper bound ≤ 33%), or whether there is uncertainty about fulfilment. Reasoning points are reported for criteria with uncertain outcome. According to the assessment here performed, it is uncertain whether AMR S. aureus can be considered eligible to be listed for Union intervention according to Article 5 of the AHL (60-90% probability). According to the criteria in Annex IV, for the purpose of categorisation related to the level of prevention and control as in Article 9 of the AHL, the AHAW Panel concluded that the bacterium does not meet the criteria in Sections 1, 2 and 4 (Categories A, B and D; 1-5%, 5-10% and 10-33% probability of meeting the criteria, respectively) and the AHAW Panel was uncertain whether it meets the criteria in Sections 3 and 5 (Categories C and E, 33-90% and 60-90% probability of meeting the criteria, respectively). The animal species to be listed for AMR S. aureus according to Article 8 criteria include mainly mammals, birds, reptiles and fish.
... El Staphylococcus aureus es causa común de infecciones superficiales y profundas en vacas lecheras y humanos (4,15,21) . En vacas lecheras, es una de las bacterias que con mayor frecuencia causa mastitis, lo que la convierte en potencial contaminante para el ser humano si no se siguen las medidas sanitarias en el ordeño, manipulación y esterilización de la leche (11) . ...
Staphylococcus aureus is one of the main microorganisms responsible of subclinical mastitis in dairy cows. To determine the bayesian prevalence of S. aureus of cows in large and small dairy farms located in the northern, central and southern region of the Valle del Cauca province in Colombia. We Followed the National Mastitis Council methodology, 1070 milk samples from 273 cows in 17 dairy farms by means of a multi-stage sampling, were collected during the period 2015-2016. Cultivation was carried out with all the samples. Bayesian inference was used. The prevalence of the pathogen S. aureus in dairy cows in Valle del Cauca is 31,94% and there is a 95% probability that the interval (30,03 – 37,62%). The North, Central and South regions showed prevalence values of 33%, 34% and 24% respectively. Small dairy farms have prevalence, 47%, large dairy farms 17%.
... El Staphylococcus aureus es causa común de infecciones superficiales y profundas en vacas lecheras y humanos (4,15,21) . En vacas lecheras, es una de las bacterias que con mayor frecuencia causa mastitis, lo que la convierte en potencial contaminante para el ser humano si no se siguen las medidas sanitarias en el ordeño, manipulación y esterilización de la leche (11) . ...
El Staphylococcus aureus es uno de los principales microorganismos causantes de mastitis subclínica en las vacas lecheras. Determinar la prevalencia del S. aureus se hace necesario en vacas de hatos lecheros grandes y pequeños ubicados en la región norte, centro y sur del departamento del Valle del Cauca, Colombia. Se utilizó la metodología del National Mastitis Council recolectando 1070 muestras de leche de 273 vacas en 17 hatos mediante un muestreo polietápico, durante el periódo 2015 - 2016. Se realizó cultivo con todas las muestras recolectadas independientemente del resultado de la prueba de California mastitis test. Se utilizó el análisis bayesiano de los datos para obtener estimaciones más precisas. La prevalencia bayesiana del patógeno S. aureus en vacas lecheras en el Valle del Cauca fue de 31,94% y se tiene un 95% de probabilidad de que el intervalo (30,03 – 37,62%) contenga el valor de dicha prevalencia. La región Norte, Centro y Sur evidenciaron prevalencias de 33%, 34% y 24% respectivamente. En cuanto al tamaño del hato se evidenció que las vacas de los hatos pequeños presentan mayor prevalencia con 47% que las vacas de los hatos grandes 17% a la presencia del patógeno. La alta prevalencia encontrada en las vacas genera un alto impacto en la salud pública debido a una posible contaminación zoonótica por este patógeno.
... Such attention to this microorganism was made to study the evolution of this bacterium in the affected cattle in Al-Diwaniyah City, Iraq. Consistent with other previously made studies (15)(16)(17), our results showed the presence of this bacterium in an important rate, 36%, in the milk of the affected cattle. The PCR showed high ability to identify the causative agent in this study. ...
This evolution-based study aimed to reliably identify the epidemiological prevalence of Escherichia coli that was recovered from affected milk of cattle by mastitis, study the evolution of this bacterium, and describe some isolates using polymerase chain reaction (PCR) technique and DNA sequencing. Here, we collected 50 cattle milk samples and submitted them to conventional bacterial isolation and identification using enrichment culture method and biochemical tests. Then, we confirmed the results by PCR technique based on 16S ribosomal RNA gene. The results showed that E. coli was isolated from cattle at (36%), and this was confirmed by PCR that showed highly specific detection of E. coli isolates at (100%). DNA sequencing of partial 16S ribosomal RNA gene showed (99%) homological identity with NCBI-Blast E. coli isolates and the phylogenetic analysis showed genetic similarity (0.5 genetic changes). In conclusion, this was the first study in Iraq to report genetic relationship between E. coli isolated from milk of mastitis-infected cattle. Therefore, it is essential to define the role of animals as an important source in the distribution of some pathogens that are related to public health.
... Such attention to this microorganism was made to study the evolution of this bacterium in the affected cattle in Al-Diwaniyah City, Iraq. Consistent with other previously made studies (15)(16)(17), our results showed the presence of this bacterium in an important rate, 36%, in the milk of the affected cattle. The PCR showed high ability to identify the causative agent in this study. ...
... On the other hand, if certain NAS species would have a positive effect on MY or if the protective effects of NAS IMI against infections with major pathogens demonstrated in challenge studies would hold true in larger observational studies(Reyher et al., 2012b), they could be interesting in the development of new concepts or strategies in the dairy sector. Studies scrutinizing the association between NAS IMI and MY have come to contradictory conslusions, with some classifying NAS as pathogens with a potential negative effect on MY Gröhn et al., 2004;, some reporting the absence of association with MY, and others finding a higher MY in infected animals than in noninfected animals. ...
... If IMI with all of the different NAS species have a negative or no effect on MY, the focus should remain on prevention of infection with these pathogens because NAS IMI lead to an elevated SCC and have been previously identified as a risk factor for developing IMI with S. aureus (Reyher et al., 2012a). On the other hand, if certain NAS species have a positive effect on MY or if the protective effects of NAS IMI against infections with major pathogens demonstrated in challenge studies hold true in larger observational studies (Reyher et al., 2012b), they could be interesting in the development of new concepts or strategies in the dairy sector. A downside of most previous studies scrutinizing the association between NAS IMI and MY is that the IMI status of the cow was an aggregate of the IMI statuses of the quarters, and that MY was also measured at the cow level. ...
We conducted a longitudinal study to evaluate the effect of non-aureus staphylococci (NAS) causing subclinical intramammary infections (IMI) on quarter milk somatic cell count (qSCC) and quarter milk yield (qMY). In total, 324 quarters of 82 Holstein Friesian heifers were followed from calving to 130 d in milk (DIM) and were sampled 10 times each at 14-d intervals. The IMI status of each quarter was determined based on bacterial culture results at the current and previous or next sampling day, or both. The qSCC was determined on each sampling day and the average qMY on sampling day was available through stored daily milk weight data in the management program of the automatic milking system. A transient IMI (tIMI) was defined as a case where a specific pathogen was isolated from a quarter on only one sampling day and not on the previous or next sampling day. When the same bacterial strain, as defined by random amplification of polymorphic DNA-PCR, was isolated from the same quarter on multiple sampling days, it was defined as a persistent IMI (pIMI) status on those sampling days; a pIMI episode was defined as the combination of multiple consecutive pIMI statuses with the same bacterial strain on different sampling days. During this study, 142 subclinical IMI with NAS occurred in 116 different quarters from 64 animals, yielding in total 304 NAS isolates belonging to 17 different species. The prevalence of NAS was highest in the first 4 DIM. Overall, the predominant species was Staphylococcus chromogenes (52% of the isolates), followed by S. epidermidis (9.2%), S. xylosus (8.2%), and S. equorum (5.9%). Staphylococcus chromogenes was the only species for which an effect on qSCC and qMY could be analyzed separately; the other NAS species were considered as a group because of their low prevalence. Eighteen out of 40 IMI (45%) caused by S. chromogenes persisted over at least 2 sampling days, whereas only 10 of 102 (9.8%) IMI caused by other NAS species persisted for at least 2 sampling days. The average duration of pIMI episodes was 110.4 d for S. chromogenes and 70 d for the other NAS species. Remarkably, 17 of the 18 pIMI episodes with S. chromogenes started within the first 18 DIM. The qSCC was highest in quarters having a pIMI with a major pathogen, followed by quarters having a pIMI with S. chromogenes, and a pIMI with other NAS. Transient IMI with other NAS or with a major pathogen caused a small but significantly higher qSCC, whereas the qSCC in quarters having a tIMI with S. chromogenes was not statistically different compared with noninfected quarters. No significant differences in qMY were observed between quarters having a pIMI or tIMI with S. chromogenes or with the other NAS species compared with noninfected quarters, despite the higher qSCC. Quarters having a pIMI with major pathogens showed significantly lower daily milk production. Surprisingly, quarters that cured from an IMI with S. chromogenes had a significantly lower qMY than noninfected quarters.
... An increase in SCC comparable to a Staphylococcus aureus IMI Fry et al., 2014;Valckenier et al., 2020) and the ability to cause persistent IMI (Rajala-Schultz et al., 2009;Mørk et al., 2012;Valckenier et al., 2020) or even mild clinical mastitis (Taponen et al., 2006;Simojoki et al., 2009;Verbeke et al., 2014) have been reported. At the same time, protective effects against other major mastitis pathogens of NAS IMI or NAS teat apex colonization have been described (De Vliegher et al., 2004;Piepers et al., 2009) Distribution of non-aureus staphylococci from quarter milk, teat apices, and rectal feces of dairy cows, and their virulence potential A. Wuytack, 1 A. De Visscher,2 S. Piepers, 1 F. Boyen, 3 F. Haesebrouck, 3 and S. De Vliegher 1 * and several authors describe little to no negative effects on udder health (Matthews et al., 1991;Reyher et al., 2012) and milk yield (Pearson et al., 2013;Valckenier et al., 2019). Additional research into the virulence potential of NAS (e.g., by comparing their presence in milk samples from healthy quarters and from quarters with clinical mastitis and by comparing the frequency of virulence genes in NAS isolates originating from these 2 opposite strata) would be helpful in that respect. ...
Non-aureus staphylococci (NAS) are predominantly isolated from bovine milk samples of quarters suffering from subclinical mastitis. They are also abundantly present on dairy cows' teat apices and can be recovered from bovine fecal samples, as recently described. Differences in ecology, epidemiology, effect on udder health, and virulence or protective traits have been reported among the species within this group. The objectives of this study were (1) to describe the species-specific distribution of NAS in 3 bovine-associated habitats, namely quarter milk, teat apices, and rectal feces, and (2) to evaluate the virulence potential of NAS by comparing their distribution in contrasting milk sample strata and the presence of selected virulence genes. A cross-sectional, systematic sampling procedure was followed in 8 dairy herds that participated in the local Dairy Herd Improvement program in Flanders, Belgium. Quarter milk samples (n = 573) were collected from 144 lactating cows in 8 herds. In 5 of the 8 herds, teat apex swabs (n = 192) were taken from 15 lactating cows, before and after milking, and from 18 dry cows. In the same 5 herds, rectal feces were sampled from 80 lactating cows (n = 80), taking into account that a cow could only serve as the source of one type of sample. In addition, milk samples of all clinical mastitis cases were continuously collected during the 1-yr study period from March 2017 to March 2018 in the 8 herds. In total, 1,676 Staphylococcus isolates were phenotypically identified and subjected to MALDI-TOF mass spectrometry. Thirty-three, 98, and 28% of all quarter milk, teat apex, and rectal fecal samples were NAS-positive, respectively, reaffirming the presence of NAS in rectal feces. The overall predominant species in the 3 habitats combined were Staphylococcus haemolyticus, Staphylococcus chromogenes, and Staphylococcus hominis. Four, 16, and 12% of the healthy quarters (quarter milk somatic cell count ≤50,000 cells/mL of milk), quarters with subclinical mastitis (quarter milk somatic cell count >50,000 cells/mL of milk), and quarters with clinical mastitis, respectively, were NAS-positive, suggesting that the potential to cause (mild) clinical mastitis is present among NAS. This was substantiated by comparing the presence of virulence genes of NAS isolates originating from contrasting milk sample strata (healthy quarters and quarters with clinical mastitis).
... aureus; isolation of Corynebacterium spp. and CNS was considered NIMI caused by CNS [22]. ...
Internal teat sealant (ITS) at drying off is a strategy used for the prevention of intramammary infections (IMI) during the dry period (DP), as it simulates the keratin plug’s purpose, which is to prevent the access of pathogens into the mammary gland. The results from randomized clinical trials provide valuable information about the efficacy of commercially available products to be used in dairy cattle, assisting farmers to choose the best protocols for mastitis control. This study evaluated a new ITS infused at drying off as an alternative to prevent IMI during DP in a tropical country. Our results showed no effect of treatments on risk of bacteriological cure, subclinical mastitis (SCM) cure, and new cases of SCM postpartum. On the other hand, the use of ITS combined with an intramammary antibiotic (SDCT) reduced the risk of clinical mastitis up to 60 days postpartum, the overall risk of new intramammary infections (NIMI), and the NIMI caused by major pathogens compared to the use of antimicrobial alone (ADCT). Thus, the use of ITS combined with an antimicrobial at drying off was effective to prevent NIMI and clinical mastitis up to 60 days postpartum.
... Case definition varied within the single outcome of IMI at calving. The exact role of existing minor pathogen IMI on the risk of new major pathogen IMI is unclear, as a protective effect has been reported in challenge trials, but not observational studies, and there is a large amount of heterogeneity in these meta-analyses (Reyher et al., 2012). If the existing infection does influence the risk of a new infection, then it is important that primary research consider this and ensure adequate reporting of the case definition. ...
A systematic review and network meta-analysis were conducted to assess the relative efficacy of antimicrobial therapy given to dairy cows at dry-off. Eligible studies were controlled trials assessing the use of antimicrobials compared to no treatment or an alternative treatment, and assessed one or more of the following outcomes: incidence of intramammary infection (IMI) at calving, incidence of IMI during the first 30 days in milk (DIM), or incidence of clinical mastitis during the first 30 DIM. Databases and conference proceedings were searched for relevant articles. The potential for bias was assessed using the Cochrane Risk of Bias 2.0 algorithm. From 3480 initially identified records, 45 trials had data extracted for one or more outcomes. Network meta-analysis was conducted for IMI at calving. The use of cephalosporins, cloxacillin, or penicillin with aminoglycoside significantly reduced the risk of new IMI at calving compared to non-treated controls (cephalosporins, RR = 0.37, 95% CI 0.23–0.65; cloxacillin, RR = 0.55, 95% CI 0.38–0.79; penicillin with aminoglycoside, RR = 0.42, 95% CI 0.26–0.72). Synthesis revealed challenges with a comparability of outcomes, replication of interventions, definitions of outcomes, and quality of reporting. The use of reporting guidelines, replication among interventions, and standardization of outcome definitions would increase the utility of primary research in this area.
... Summary of the overall quality of evidence of the network of studies examining the efficacy of teat sealant protocols to prevent new intramammary infections (IMI) at calving, using the Confidence In Network Meta-Analysis (CINeMA) platform (http://cinema.ispm.ch), with a modified approach, to determine the risk of bias due to the approach to randomization, blinding, imprecision, and heterogeneity existing minor pathogen IMI on the risk of new major pathogen IMI is unclear; based on a systematic review and meta-analysis, a protective effect has been reported in challenge trials, but not observational studies, and there is a large amount of heterogeneity in these meta-analyses (Reyher et al., 2012). If the existing infection does influence the risk of a new infection, then it is important that primary research consider this and ensure adequate reporting of the case definition. ...
A systematic review and network meta-analysis were conducted to assess the relative efficacy of internal or external teat sealants given at dry-off in dairy cattle. Controlled trials were eligible if they assessed the use of internal or external teat sealants, with or without concurrent antimicrobial therapy, compared to no treatment or an alternative treatment, and measured one or more of the following outcomes: incidence of intramammary infection (IMI) at calving, IMI during the first 30 days in milk (DIM), or clinical mastitis during the first 30 DIM. Risk of bias was based on the Cochrane Risk of Bias 2.0 tool with modified signaling questions. From 2280 initially identified records, 32 trials had data extracted for one or more outcomes. Network meta-analysis was conducted for IMI at calving. Use of an internal teat sealant (bismuth subnitrate) significantly reduced the risk of new IMI at calving compared to non-treated controls (RR = 0.36, 95% CI 0.25–0.72). For comparisons between antimicrobial and teat sealant groups, concerns regarding precision were seen. Synthesis of the primary research identified important challenges related to the comparability of outcomes, replication and connection of interventions, and quality of reporting of study conduct.
... Streptococcus uberis infections lead to milk production losses and increased SCC (Reyher et al., 2012;Heikkilä et al., 2018). Streptococcus uberis IMI are to a considerable extent clinically apparent, with visible changes to the milk secretion, palpable udder tissue alterations, and increased body temperature. ...
Streptococcus uberis, a major mastitis pathogen associated with intramammary infections (IMI), can be found ubiquitously in the cow's environment. Although Strep. uberis is reported to be susceptible to most antimicrobials, in practice poor responses to treatment and recurrent mastitis are observed. This can be explained by reinfection or by persistence of strains. We hypothesized that among a heterogeneous group of Strep. uberis mastitis isolates, some predominant host-adapted clones might be recurrently isolated from IMI. Therefore, the aim of this pilot study was to determine the Strep. uberis genotype variety found among small-scale dairy herds (127 Austrian dairy farms) and compare this with a large-scale herd (a Slovakian dairy farm). We determined the occurrence and strain diversity of Strep. uberis (n = 309) isolates using molecular analysis. Streptococcus uberis isolates from aseptically collected quarter milk samples were genotypically characterized using pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing. The Strep. uberis strain set covered isolates from 4 Austrian federal areas [Lower Austria (n = 67), Upper Austria (n = 8), Salzburg (n = 51), and Styria (n = 1)] and the Bratislava Region of Slovakia (n = 1). The PFGE analysis resulted in 187 SmaI profiles with 151 unique profiles. Simpson's index of diversity was 0.988. Individual cows (n = 17) harbored up to 3 different PFGE types in the udder. Dairy cows shared distinct PFGE types within a farm. Seven PFGE types were widely distributed among Austrian dairy farms. In the Slovakian farm, 10 predominant PFGE types were recurrently isolated from the same quarters; these genotypes were assigned as persisters. We identified novel sequence types (ST) using multilocus sequence typing related to the global clonal complexes ST5 and ST143. We concluded that Strep. uberis IMI are caused by strains with a wide heterogeneity of PFGE types. This large number of unique subtypes indicates a high diversity of Strep. uberis in the environment. In the large herd, molecular epidemiological results revealed that specific strains might be involved in contagious transmission events and potentially lead to persistence.
... Even though several contagious and environmental pathogens can be involved in causing mastitis, Staphylococcus aureus, Streptococcus uberis, S. agalactiae, S. dysgalactiae and Escherichia coli are the most common (Ranjan et al. 2006) and are usually associated with more severe mastitis (Reyher et al. 2012). According to Keefe (2012), S. agalactiae and S. aureus are considered bovine mastitis primary pathogens due to its impact in the production and quality of milk, especially in BMSCC. ...
High bulk milk somatic cell counts (BMSCC) are indicative of failures related to the control of mastitis in the herd, which compromises the quality of the milk and generates great losses for the producers and for the industry. A case-control study was carried out in dairy herds in the Campos das Vertentes region, Minas Gerais State, Brazil, in order to contribute to the knowledge of the risk factors involved with elevated BMSCC. The study involved 46 dairy herds, of which 30 were considered cases (BMSCC ≥700,000 cells/mL of milk) and 16 control farms (BMSCC ≤200,000 cells/mL of milk). Sixteen qualitative variables and four quantitative variables were analyzed. The results showed that the risk factors for BMSCC ≥700,000 cells/mL were the presence of Staphylococcus aureus and Streptococcus agalactiae pathogens in bulk milk, non-use of pre and post-dipping, non-use of disposable paper towel for drying of mammary glands, non-monitoring of mastitis in the herd by means of California Mastitis Test (CMT) or individual somatic cell counts (SCC), non-implementation of the milking line and therapy of dry cows and failures in hygiene of teats and udders before milking. Moderate correlations were also observed between the elevation of BMSCC and counts of S. aureus and BMSCC and counts S. agalactiae in bulk milk, and a moderate correlation between S. aureus and S. agalactiae counts in bulk milk. Failures with regard to the maintenance and use of milking equipment, including manual pressure application in milking assemblies, unregulated milking vacuum pressure, and vacuum loss during milking, and maintenance failures of the milking machine and bulk milk tank were also pointed out as important risk factors of BMSCC elevation. The results of this study provided subsidies for the elaboration of more effective programs for mastitis control and improvement of raw milk quality, reducing the losses caused by the disease to producers and industry.
... Bovine mastitis can be caused by different agents, including bacteria, viruses, fungi, and algae (Ranjan et al. 2006, Reyher et al. 2012). Among the bacteria, Staphylococcus aureus and Streptococcus agalactiae are the most frequently isolated pathogens in intramammary infections in Brazilian cattle. ...
Bovine mastitis is the most frequent disease worldwide in dairy herds, causing high economic losses to producers and industry, as well as having implications for public health due to the zoonotic potential of some agents involved in its etiology and the increased risk of antimicrobial residues in milk and its derivatives. Considering the multifactorial aspect of this disease, knowledge of the agents involved in its etiology and their antimicrobial susceptibility profiles is very important. This study was conducted with 306 dairy herds from the Campo das Vertentes region, located in the south of Minas Gerais state, whose owners were milk suppliers to a dairy in the same region. The study involved approximately 34,000 dairy cows and covered an area of approximately 12,564 km2. In these herds, prevalence rates of Staphylococcus aureus and Streptococcus agalactiae and their relationship with bulk milk somatic cell counts (BMSCC), total bacterial counts (TBC), and daily production were evaluated. In addition, analyses of resistance of these pathogens to the antimicrobials most commonly used in the treatment of mastitis in dairy herds were performed. Microbiological analyses of milk samples from collect from bulk milk tanks were performed aiming to evaluate the prevalence of S. aureus and S. agalactiae. For these proposes, the modified Baird-Parker Agar medium was used for detection of S. aureus and the modified Edwards Agar medium, enriched with 5% defibrinated sheep blood, was used for detection of S. agalactiae. The disc diffusion technique was applied to evaluate antimicrobial resistance. Results show high prevalence rates of S. aureus (70.3%) and S. agalactiae (67.0%) in the dairy farms studied, with 47.71% of the herds showing both pathogens. Associations between BMSCC and the presence of pathogens S. aureus and S. agalactiae and between TBC and the presence of S. agalactiae were observed, demonstrating the influence of these pathogens in milk quality. No variation was observed in the distribution of S. aureus and S. agalactiae in the different strata of daily production. High levels of resistance and multi-resistance were observed among the pathogens S. aureus and S. agalactiae. The results indicate the need for more effective control measures for mastitis caused by S. aureus and S. agalactiae in the dairy herds of the region studied and more judicious use of antimicrobials in order to reduce the problem of resistance to them.
... In subclinical mastitis, there are no observable or palpable changes in the udder or secreted milk; however, clinical mastitis is always associated with abnormalities of the udder (such as edema, redness, warmness, pain on palpation, fibrosis) and milk (such as flakes, blood, pus or watery discharge). Regardless of the fact that mastitis is caused by vast range of microbial species (Smith and Hogan 2001), the majority of intramammary infections (IMI) are caused by bacterial pathogens such as Staphylococcus aureus, coagulase-negative staphylococci (CNS), Streptococcus spp., and Escherichia coli (Reyher et al. 2012). The distribution of mastitis pathogens differs within individual animals in a herd, and between herds, host species, and countries (Dhakal et al. 2007, Sharma et al. 2012, Tufani et al. 2012, Oliveira et al. 2013, Gao et al. 2017 and largely attributed to herd- (Gao et al. 2017, Taponen et al. 2017, cow- (Taponen et al. 2017, Vlkova et al. 2017, and season-specific factors (Makovec and Ruegg 2003, Olde Riekerink et al. 2008, Gao et al. 2017. ...
The present study determined trends in the isolation of bacterial pathogens in milk samples submitted from clinical mastitis buffaloes at the University mastitis laboratory during 2007 to 2016. Culture results (n = 3945) were classified into six categories (Staphylococcus spp., 28.7%; Streptococcus spp., 1%; Corynebacterium spp., 1.1%; gram-negative organisms, 3.2%; others including mixed growths, 3.3%; and no growth, 62.7%). Overall, culture results were significantly associated with year (χ² = 112.28; df = 10; P < 0.001) and season (χ² = 136.03; df = 20; P < 0.001). From 2007–2009 to 2013–2016, the isolation of Staphylococcus spp. increased from 28.2 to 48.4%, while isolation of Streptococcus spp. (50 to 20%) and Corynebacterium spp. (65.1 to 16.3%) decreased. The proportion of samples characterized as no growth increased from 26.4% (2007–2009) to 46.3% (2013–2016). Further, the proportion of clinical mastitis cases increased over the study years (goodness-of-fit χ² = 59; df = 2; P < 0.001). With respect to season, the proportion of Staphylococcus spp. (30.6%; 346/1132), Corynebacterium spp. (48.8%; 21/43), and gram-negative bacteria (55.9%; 71/127) were more associated with the monsoon, and that of Streptococcus spp. (47.5%; 19/40) with the winter. Seasonal effects were also observed on the occurrence of clinical mastitis cases; comparatively, more clinical mastitis cases (35.6%; 523/1473) were observed during the monsoon season (goodness-of-fit χ² = 276.7; df = 4; P < 0.001) as compared with other seasons. The present study concludes that Staphylococcus spp. are the major cause of intramammary infections in buffaloes with clinical mastitis, demanding more studies regarding its epidemiology and pathogenicity. Also, more efforts are needed in the prevention and control of clinical mastitis in buffaloes, especially, during the monsoon season.
... According to (El-Khodery and Osman, 2008), coliform bacteria (Klebsiella pneumoniae and Escherichia coli) was the most common pathogen followed by Staphylococcus aureus, Streptococcus uberis and Streptococcus agalactiae. Similarly, in cattle, S. aureus, S. agalactiae, S. uberis, Streptococcus dysgalactiae, and the coliforms are major mastitis pathogens and Corynebacterium bovis and coagulase-negative Staphylococci are minor mastitis pathogens (Reyher et al., 2012). ...
Buffalo milk production has become of significant importance on the world scale, however, there are few studies involving biotechnological tools specifically for buffalo. To verify the effects caused by subclinical mastitis on the components of milk and to study the innate immune system in the udder of dairy buffaloes with subclinical mastitis, we evaluated the levels of expression of the lactoferrin ( LTF ), tumor necrosis factor alpha ( TNF-α ), interleukin-1 beta ( IL-1β ), interleukin-8 ( IL-8 ), and toll-like receptors 2 ( TLR-2 ) and 4 ( TLR-4 ) genes in buffaloes with and without subclinical mastitis. Milk samples were collected for the determination of milk components: somatic cell score (SCS), fat, protein, lactose, total solids and solids-not-fat (SNF), as well as for RNA extraction of milk cells, complementary DNA synthesis, and expression profile quantification by quantitative real-time PCR. For gene expression, the ΔΔCt was estimated using contrasts of the target genes expression adjusted for the expression of the housekeeping genes between both groups. Linear regression analysis was performed to determine the relationship between the genes studied and the milk components. Subclinical mastitis induced changes in the fat, lactose and SNF in milk of buffaloes, and the messenger RNA abundance was upregulated for TLR-2, TLR-4, TNF-α, IL-1β and IL-8 genes in milk cells of buffaloes with subclinical mastitis, whereas the LTF gene was not differentially expressed. Results of linear regression analysis showed that TLR-2 gene expression most explains the variation in SCS, and the change in a unit of ΔCt of the TNF-α gene would result in a higher increase in SCS. The study of these immune function genes that are active in the mammary gland is important to characterize the action mechanism of the innate immunity that occurs in subclinical mastitis in dairy buffaloes and may aid the development of strategies to preserve the health of the udder.
... CeNGIZ et al. (2014), MILaNOV et al. (2015) and GaLFI et al. (2016) indicated that the most important major mastitis pathogens are Staphylococcus aureus and S. agalactiae, as contagious pathogens, and S. uberis, S. dysgalactiae, Escherichia coli and Enterococcus sp., as environmental pathogens. the presence of minor mastitis pathogens (Corynebacterium sp. and coagulase-negative staphylococci), is increasing significantly in udders, probably due to the fact that the prevalence of the major pathogens is decreasing (PYÖRÄLÄ and TAPONEN, 2009;REYHER et al., 2012;IDRISS et al., 2013;GALFI et al., 2016). In their study, MAĆEŠIĆ et al. (2012) indicated a rise in the importance of environmental pathogens in the epidemiology of bovine mastitis ( GaLFI et al., 2016). ...
________________________________________________________________________________________ MuRuzović, M. Ž., K. G. MLaDenović, T. D. ŽuGić-PeTRović, Lj. R. ČoMić: In vitro evaluation of the antimicrobial potential of Streptococcus uberis isolated from a local cheese from Southeastern Serbia. vet. arhiv 88, 521-534, 2018. aBSTRaCT Streptococcus uberis is an environmental bacterium responsible for bovine mastitis. It is occasionally described as a human pathogen. In our study, the isolation was undertaken of lactic acid bacteria from a local cheese from Southeastern Serbia, produced in a traditional way. S. uberis (7 isolates) and S. agalactiae (1 isolate) were isolated from the cheese samples taken in the summer. the biochemical and physiological characteristics of the isolates were examined. Using tetracycline, chloramphenicol, novobiocin and rifampicin, the antibiotic susceptibility of the isolates was evaluated. the results demonstrated that all the isolates were susceptible to all the tested antibiotics, with a growth inhibition zone from 36-48 mm. also, the antagonism was examined of S. uberis kGPMF1-7 and S. agalactiae kFPMF8 isolates on the growth of Escherichia coli atCC 25922, Proteus mirabilis atCC 12453, Klebsiella oxytoca kGPMF1, Klebsiella ornithinolytica kGPMF8 and Aeromonas hydrophila, as indicator stains. the results were compared with the activities of chloramphenicol, streptomycin and tetracycline on the tested indicator stains. the strongest antagonism was demonstrated by all Streptococcus isolates on the growth of K. oxytoca kGPMF1 (growth inhibition zone from 12-20 mm) and the A. hydrophila (growth inhibition zone from 13-20 mm). When these results were compared with the results of the sensitivity of tested indicator stains to antibiotics, S. uberis kGPMF1-7 and S. agalactiae kGPMF8 isolates showed a moderate antagonistic effect. Due to the specific way cheese is made in from Sokobanja, these isolates probably originate from cows' udders.
... As well, IMI with minor pathogens have not always been associated with protection against clinical mastitis (Green et al. 2004) or IMI with major pathogens (Reyher et al. 2012a). Overall, the protective effects of IMI with minor pathogens against IMI with major pathogens seem to be more pronounced in challenge studies, specifically when major pathogens were introduced into the mammary gland via methods bypassing the teat end, than in observational studies (Reyher et al. 2012b). ...
Mastitis is a complex, multifactorial disease. Pathogens, cows and farmers (via management) all play a role. It is costly and annoying for the farmer and threatens the image of the entire dairy industry. Prevention and control of mastitis is based on multiple principles that have been known for a long time. To implement them successfully, they should be put forward by a motivated and motivating advisor that transfers the existing knowledge to the farmer. When the changes are data-driven, applied by an encouraged farmer through a farm-specific implementation, prevention and control of mastitis will be successful and result in happy cows, happy farmers, happy advisors, happy consumers, and a happy industry. Nationwide projects focussing on communication and transfer of existing knowledge in prevention and control are very helpful in reaching high numbers of farmers and advisors and harmonizing the message brought by different parties. This paper gives an overview of multifactorial approach of mastitis management and prevention with a focus on milking, bedding and data-analysis.
... As well, IMI with minor pathogens have not always been associated with protection against clinical mastitis (Green et al. 2004) or IMI with major pathogens (Reyher et al. 2012a). Overall, the protective effects of IMI with minor pathogens against IMI with major pathogens seem to be more pronounced in challenge studies, specifically when major pathogens were introduced into the mammary gland via methods bypassing the teat end, than in observational studies (Reyher et al. 2012b). ...
Milk quality in bulk tank milk (BTM) is measured by flow cytometry technology as total bacterial count (TBC) and somatic cell count (SCC). To investigate SCC problems, culture or PCR can be used to identify mastitis causing bacteria, e.g., Mastit 4, a commercially available qPCR test. TBC in BTM can be investigated further using culture-based methods such as standard plate count, laboratory pasteurization count, coliform count, and spore counts. To our knowledge, no qPCR addressing the bacteria involved in TBC has been commercially introduced. The aim of this study is to evaluate a recently introduced 3-h qPCR test, TBC 4. The TBC 4 qPCR detects four target groups, Pseudomonas, Streptococci, Enterobacteriacea/Enterococcus, and Bacillus/Clostridia. These target groups relate to problems on the farm such as cooling, mastitis, environment, and silage. We will continue with new research to compare the TBC 4 qPCR test with traditional culture. For this study, BTM samples from different TBC intervals were selected based on BactoCount results found at routine payment investigation at Eurofins laboratory (Vejen, Denmark). These samples were analyzed using TBC 4 qPCR assay within 24 h. In total, 346 BTM samples were divided into six different intervals of colony forming units (CFU). For all four targets in each of the different intervals of CFU, the percent of positive samples, the average Ct-value, the percent of positive samples with Ct
... Low-grade inflammations such as those caused by the so-called minor pathogens (CNS or Corynebacterium bovis) are enough to reduce the rate of success of experimental infections (Postle et al., 1978;Linde et al., 1980;Poutrel and Lerondelle, 1980;Schukken et al., 1999). Field experiments have sometimes documented some protection afforded by infections by minor pathogens against new infections by major pathogens such as S. aureus, streptococci, or coliform bacteria, although with moderate efficacy (Black et al., 1972;Bramley, 1975;Brooks et al., 1983;Bradley, 2002;Piepers et al., 2010;Piepers et al., 2013), and overall less convincingly than did experimental challenge studies (Reyher et al., 2012). The leukocyte barrier concept was implemented by intentionally inducing a chronic inflammation in the udder. ...
An enduring controversy exists about low milk cell counts and susceptibility to mastitis. The concentration of milk leukocytes, or somatic cell count (SCC), is a well-established direct indicator of mammary gland inflammation that is highly correlated with the presence of a mammary infection. The SCC is also used as a trait for the selection of dairy ruminants less prone to mastitis. As selection programs favor animals with less SCC, and as milk cells contribute to the defense of the mammary gland, the idea that susceptibility to mastitis could possibly be increased in the long term has been put forward and is still widely debated. Epidemiological and experimental studies aimed at relating SCC to susceptibility to mastitis have yielded results that seem contradictory at first sight. Nevertheless, by taking into account the immunobiology of milk and mammary tissue cells and their role in the defense against infection, along with recent studies on SCC-based divergent selection of animals, the issue can be settled. Apparent SCC-linked susceptibility to mastitis is a phenotypic trait that may be linked to immunomodulation but not to selection.
... uberis, Str. dysgalactiae and Escherichia (E.) coli [45]. However, the 'minor' pathogens, including coagulase-negative staphylococci (CNS) and various bacilli have attracted increasing attention [41]. ...
This study described the occurrence of clinical and subclinical forms of mastitis in 250 cattle from 5 dairy farms around the cities of Santa Rosa and Machala, El Oro Province, Ecuador. Clinical mastitis (CM) was determined based on obvious changes in milk (mild), signs of inflammation in the udder (moderate), and/or generalized clinical symptoms (severe). Subclinical mastitis (SCM) was assessed using the California mastitis test. CM and SCM were detected in 30 (12.0%) and 150 (60%) of the 250 tested cattle, respectively. Prevalence at the udder quarter level was 57.7% (577/1000), which was higher among forequarters (369/577; 63.9%) than hindquarters. Of the 577 mastitic milk samples subjected to microbiological analysis, 35 were excluded due to contamination and 20 tested negative. Identification of bacterial isolates revealed that 33.3% of the 93 CM samples contained coliforms, 25.8% coagulase-positive staphylococci, 20.4% coagulase-negative staphylococci (CNS), 9.7% streptococci, 7.5% Bacillus spp., and 3.2% Klebsiella spp. Bacterial profiling of the 429 SCM milk samples showed that 55.4% contained CNS, 22.1% Bacillus spp., 9.3% streptococci, and 6.1% coagulase-positive staphylococci. In vitro antibiotic susceptibility testing of the obtained isolates indicated that all were susceptible to amoxicillin, ampicillin, cefotaxime, enrofloxacin, sulfamethoxazole-trimethoprim, gentamicin, and neomycin. No multidrug-resistant strains were observed.
... When analyzed as 3 different groupings of 8 different species, those quarters treated with antimicrobials at dry-off experienced statistically lower odds of having an IMI characterized by CNS at calving relative to those that were not treated (De Visscher et al., 2016). However, there might be an advantage to the presence of CNS in quarters: some groups have observed higher milk production in CNSinfected animals relative to uninfected animals (Schukken et al., 2009;Piepers et al., 2013), and other groups, as reflected in a meta-analysis, see a protective effect of CNS against major pathogens in challenge studies (Reyher et al., 2012). Conversely, Berry and Hillerton (2002) found, when assessing 499 quarters, that untreated quarters with CNS infections had a 4.2 to 4.7 times greater risk of new infections with Streptococcus uberis or coliforms at calving compared with uninfected, untreated quarters. ...
An algorithm using only computer-based records to guide selective dry-cow therapy was evaluated at a New York State dairy farm via a randomized field trial. DairyComp 305 (Valley Ag Software, Tulare, CA) and Dairy Herd Improvement Association test-day data were used to identify cows as low risk (cows that might not benefit from dry-cow antibiotics) or high risk (cows that will likely benefit). Low-risk cows were those that had all of the following: somatic cell count (SCC) ≤200,000 cells/mL at last test, an average SCC ≤200,000 cells/mL over the last 3 tests, no signs of clinical mastitis at dry-off, and no more than 1 clinical mastitis event in the current lactation. Low-risk cows were randomly assigned to receive intramammary antibiotics and external teat sealant (ABXTS) or external teat sealant only (TS) at dry-off. Using pre-dry-off and postcalving quarter-level culture results, low-risk quarters were assessed for microbiological cure risk and new infection risk. Groups were also assessed for differences in first-test milk yield and linear scores, individual milk weights for the first 30 d, and culling and mastitis events before 30 d in milk. A total of 304 cows and 1,040 quarters in the ABXTS group and 307 cows and 1,058 quarters in the TS group were enrolled. Among cows to be dried, the proportion of cows that met low-risk criteria was 64% (n = 611/953). Of cultures eligible for bacteriological cure analysis (n = 171), 93% of ABXTS cured, whereas 88% of TS cured. Of the non-cures, 95% were contributed by the minor pathogens coagulase-negative staphylococci (n = 19/20). These organisms also accounted for 57.5% of new infections (n = 77/134). We found no statistical differences between treatment groups for new infection risk (TS = 7.3% quarters experiencing new infections; ABXTS = 5.5%), milk production (ABXTS = 40.5 kg; TS = 41.2 kg), linear scores (ABXTS = 2.5; TS = 2.7), culling events (ABXTS, n = 18; TS, n = 15), or clinical mastitis events (ABXTS, n = 9; TS, n = 5). Results suggest that the algorithm used decreased dry-cow antibiotic use by approximately 60% without adversely affecting production or health outcomes.
... Bacterias CNS, consideradas tradicionalmente como flora normal de la piel de la vaca, fueron aisladas con mayor frecuencia en muestras, tanto de mastitis clínica (80%, 8/10) como subclínica (44.8%, 82/183). Este estudio coincide con la afirmación de varios autores sobre la emergencia de CNS como patógeno causante de mastitis ( La literatura actual contiene varios estudios detallando análisis con resultados contradictorios sobre si infecciones intramamarias (IMI) con patógenos menores como los CNS presentan un riesgo de adquirir una nueva IMI por patógenos mayores (Reyher, 2012 Se presentó una alta resistencia de los principales microorganismos aislados (CNS, Staphylococcus aureus y Streptococcus spp) a la penicilina y a la eritromicina. Además, los tres grupos bacterianos mostraron multirresistencia, especialmente Streptococcus spp. ...
El objetivo de la investigación fue determinar la prevalencia de mastitis bovina y la resistencia antimicrobiana de los patógenos involucrados en una región lechera de Colombia. Los cuartos mamarios de 348 vacas fueron examinados y evaluados mediante la prueba de California para el diagnóstico de mastitis (CMT). Las muestras positivas a CMT se cultivaron para el aislamiento bacteriológico y susceptibilidad a antibióticos mediante el método de difusión en disco. El análisis de los resultados se realizó mediante estadística descriptiva y relación de prevalencia. Los resultados indican que 158 (45.4%) de las vacas fueron positivas para CMT. Se encontró mastitis clínica en siete vacas (2.0%) y mastitis subclínica en 151 vacas (43.4%). El grupo estafilococo coagulasa-negativo (SNC) fue el principal patógeno encontrado en el 46.7% de los aislamientos, seguido de Staphylococcus aureus (31.1%) y Streptococcus spp (20.7%). Klebsiella pneumoniae y E. coli tuvieron una baja ocurrencia (0.5%). CNS, Staphylococcus aureus y Streptococcus spp presentaron un alto grado de resistencia a penicilina G y a eritromicina, además de multirresistencia.
... Some CNS species seem to affect udder health more than others , De Visscher et al., 2016. The negative or positive effect might be species dependent (Reyher et al., 2012b), or even strain specific Piccart et al., 2016;Souza et al., 2016). The variable results and limitations of prior data highlight the need to identify staphylococci mastitis infections to the species level, and to obtain data that might help describe why certain species persist in different niches or cause mastitis. ...
The genus Staphylococcus contains at least 47 species and 23 subspecies. Bacteria in this genus are ubiquitous; many are commensals on human and animal skin and can be opportunistic pathogens. In dairy cattle, staphylococci are the leading cause of intramammary infections (IMI) and mastitis. Mastitis is the inflammation of the mammary gland, and is one of the leading infectious diseases causing production losses in the dairy industry. Based on the ability to clot blood plasma in vitro, members of the genus can be divided into two groups: coagulase positive staphylococci (CPS) and coagulase negative staphylococci (CNS). In the dairy industry, Staphylococcus aureus is the most common CPS causing mastitis and is considered a major mastitis pathogen compared to the CNS, which as a group have been described as minor mastitis pathogens. The CNS species are increasingly recognized as an important cause of bovine mastitis, although the relative role of some species is still uncertain. Our understanding of the local and global epidemiology of CNS mastitis is improving with application of more accurate DNA sequence-based species identification methods and techniques to discriminate between strains within species. These factors have led to a shift in perspective, with the CNS being recognized as a heterogeneous group where some species are more important than others in bovine mastitis. The major goals of this thesis were to describe Staphylococcus mastitis epidemiology, and to identify phenotypes that may contribute to persistence in various niches on selected dairy farms in Vermont. We conducted 2 field studies on 2 groups of farms in Vermont. In the first study, we collected S. aureus isolates from bulk tank milk of 44 certified organic dairy farms. In the second field study, we completed quarter milk, cow skin, and environmental sampling of 5 herds that make farmstead cheeses. In both studies, we used non-selective and selective agar medium to isolate staphylococci from the farm sources. From these studies, we collected 1,853 Staphylococcus spp. isolates. We used PCR-amplicon sequence-based species identification to describe Staphylococcus species diversity on these selected Vermont dairy farms. S. aureus isolates were strain-typed using an established Multilocus Sequence Typing (MLST) scheme. A novel MLST scheme was developed to investigate the molecular epidemiology of S. chromogenes, one of the leading CNS species causing bovine mastitis in this and other studies. We also evaluated antibiotic resistance and biofilm formation phenotypes and genotypes of staphylococci to test the hypothesis that these phenotypes may be associated with strain types. In the study of organic dairy farms, 20 S. aureus strain types (STs) were identified, including ten novel STs. The majority of STs belonged to lineages or clonal complexes (CCs) previously identified as cattle adapted (e.g. CC97 and CC151). Associations between ST and carriage of beta-lactam resistance and biofilm forming capacity were identified among the S. aureus isolates from these farms. In the 5-herd study, a total of 27 different staphylococci species were identified from various niches including humans, but only five species; S. chromogenes, S. aureus, S. haemolyticus, S. simulans, and S. xylosus were commonly identified to cause IMI. S. aureus and S. chromogenes strain types were niche specific.
... Concerning the prevention of new infections by pre-existing and long-lasting colonization of the MG by bacteria, an experiment of nature in relation to intramammary probiotics is the effect of the so-called minor pathogens Corynebacterium bovis and coagulase-negative staphylococci on the incidence of IMI by major pathogens such as S. aureus, streptococci and E. coli. Although quite a few studies reported some protective effect by minor pathogens, others have found the converse or no effect, and several ancient and recent reviews conclude that a protective effect would be of low magnitude in any case [74][75][76][77]. It is noteworthy that the efficiency of the alleged intramammary microbiota would be low, since a few (1-100) S. aureus or E. coli cfu are enough to cause mastitis with a success rate above 90% [32,78,79]. ...
Explorations of how the complex microbial communities that inhabit different body sites might contribute to health and disease have prompted research on the ways the harmonious relationship between a host and its microbiota could be used to keep animals healthy in their production conditions. In particular, there is a growing interest in the bacterial signatures that can be found in the milk of healthy or mastitic dairy cows. The concept of sterility of the healthy mammary gland of dairy ruminants has been challenged by the results of studies using bacterial DNA-based methodology. The newly obtained data have led to the concept of the intramammary microbiota composed of a complex community of diverse bacteria. Accordingly, mammary gland infections are not mere infections by a bacterial pathogen, but the consequence of mammary dysbiosis. This article develops the logical implications of this paradigm shift and shows how this concept is incompatible with current knowledge concerning the innate and adaptive immune system of the mammary gland of dairy ruminants. It also highlights how the concept of mammary microbiota clashes with results of experimental infections induced under controlled conditions or large field experiments that demonstrated the efficacy of the current mastitis control measures.
... Bacterias CNS, consideradas tradicionalmente como flora normal de la piel de la vaca, fueron aisladas con mayor frecuencia en muestras, tanto de mastitis clínica (80%, 8/10) como subclínica (44.8%, 82/183). Este estudio coincide con la afirmación de varios autores sobre la emergencia de CNS como patógeno causante de mastitis ( La literatura actual contiene varios estudios detallando análisis con resultados contradictorios sobre si infecciones intramamarias (IMI) con patógenos menores como los CNS presentan un riesgo de adquirir una nueva IMI por patógenos mayores (Reyher, 2012 Se presentó una alta resistencia de los principales microorganismos aislados (CNS, Staphylococcus aureus y Streptococcus spp) a la penicilina y a la eritromicina. Además, los tres grupos bacterianos mostraron multirresistencia, especialmente Streptococcus spp. ...
La mastitis infecciosa es una enfermedad que ha cobrado importancia en el ámbito investigativo por ser causante de pérdi‑das económicas significativas en los sistemas de producción bovino, debido a que altera la leche fisicoquímica y organolépticamente; disminuye la duración y la capacidad de lactancia de las vacas; aumenta los costos de producción y puede llegar a convertirse en un riesgo para la salud pública. El presente artículo de revisión aborda parte de los estudios adelantados sobre este tema en Colombia, los cuales han sido publicados en revistas indexadas y aparecen relacionados en las bases de datos científicas al realizar consultas con palabras clave como mastitis bovina, prevalencia, agentes etiológicos, pruebas diagnósticas. Lo anterior con el objetivo de analizar la prevalencia y los agentes bacterianos asociados a dicha enfermedad, en comparación con investigaciones de otros lugares del mundo. A pesar de la variabilidad de los estudios y de los objetos de investigación, se pudo establecer que la mastitis infecciosa bovina es una enfermedad prevalente en Colombia, especialmente en su forma subclínica, como sucede de manera similar en otros países, aunque en menor proporción. Asimismo, los patógenos bacterianos asociados con mayor frecuencia son Staphylococcus aureus, Streptococcus spp. yStaphylococcus coagulasa negativa, tanto en el contexto nacional como en el internacional.
... The most common causative agent of mastitis is Staphylococcus aureus (Contreras & Rodríquez, 2011;Makovec & Ruegg, 2003;Reyher et al., 2012;Wilson et al., 1997). It is an infectious bacterial pathogen, which is usually spread between cows during the milking process. ...
Bovine mastitis is a costly disease in the dairy industry that does not always respond to antibiotic treatment. The major components of terpeneless, cold-pressed Valencia orange oil, citral, linalool, decanal, and valencene, were examined as potential alternative treatments for Staphylococcus aureus associated mastitis. The minimum inhibitory concentration (MIC) of all four components against S. aureus was determined after 24 h incubation. Growth inhibition assay was performed for all effective components on S. aureus for either a 3 h or 72 h treatment. These components were tested for the ability to disrupt pre-formed S. aureus biofilms after 24 h of treatment by measuring absorbances at 540nm. Cytotoxicity against immortalized bovine mammary epithelial (MAC-T) cells was measured using MTT assay following a 1 h exposure. Only concentrations below the 50% cytostatic concentration (CC50) were used in an adherence and invasion assay of S. aureus on MAC-T cells and measurements of gene expression for virulence and biofilm genes via qPCR. The MICs of citral and linalool were 0.02% and 0.12%, respectively, but decanal and valencene were ineffective. Citral and linalool were capable of inhibiting growth of S. aureus after 24 h at their MIC values and inhibited pre-formed biofilms of S. aureus. The concentrations below CC50 were 0.02% for citral, and 0.12% for linalool. These concentrations inhibited the adhesion and invasion ability of S. aureus and downregulated virulence genes. Only 0.12% linalool downregulated the expression of S. aureus biofilm forming genes. These components should be considered in further in vivo study.
... Mastitis is a common and costly infectious disease affecting dairy farms (Hogeveen et al., 2011) and one of the major reasons for use of antibiotics in dairy farming (Pieterse and Todorov, 2010). Several bacteria are implicated as causative agents, including Staphylococcus aureus, Streptococcus agalactiae, Streptococcus dysgalactiae, Streptococcus uberis, and coliforms such as Escherichia coli (Reyher et al., 2012). Monitoring of udder health is most frequently done by SCC and bacteriological culturing of milk (Lam et al., 2009 ). ...
A loop-mediated isothermal amplification (LAMP) method to detect Streptococcus uberis in raw milk was developed and evaluated. Three genes (sodA, pauA, cpn60) were assessed for their suitability as targets in LAMP. The analytical sensitivity was 120, 120, and 12 fg per assay for the sodA, pauA, and cpn60 assays, respectively, with a detectable signal within 8 min for the highest concentration (12 ng/assay) and ∼60 min for the lowest concentrations. The LAMP assays correctly identified 7 Strep. uberis strains among a set of 83 mastitis pathogens. To enable DNA isolation from raw milk, a new method was used in which a pretreatment with a cocktail of lysing enzymes was performed before an established procedure. This method resulted in an analytical sensitivity of 48 cfu/assay for the sodA LAMP assay using raw milk spiked with Strep. uberis, corresponding to 2.4 × 10(4) cfu/mL milk. For raw milk samples from cows experimentally infected with Strep. uberis, results of enumeration were largely reflected by results of LAMP. Evaluation of the sodA LAMP assay with 100 raw milk field samples, of which 50 were Strep. uberis culture-negative and 50 Strep. uberis culture-positive, showed that the assay had a diagnostic sensitivity of 96.0% and a diagnostic specificity of 96.0%. In conclusion, the described LAMP assay may offer a simple alternative for convenient and sensitive detection of S. uberis in raw milk, provided a compatible rapid DNA isolation procedure is available.
... The most common bacteria associated with mastitis are Staphylococcus species, Streptococcus species, and coliforms, such as Escherichia coli and Corynebacterium. Staphylococcus species, specifically Staphylococcus aureus, are considered more virulent and the most damaging causative agent (Reyher et al., 2012). Mastitis can be clinical or subclinical; clinical mastitis is characterized by abnormal milk secretions with or without local or systemic signs of inflammation, whereas subclinical mastitis has a higher incidence rate and is most commonly diagnosed by the presence of a pathogen in milk (Barlow, 2011). ...
This experiment examined the effects of cold-pressed, terpeneless citrus-derived oil (CDO) on growth of Staphylococcus aureus, which a major cause of contagious bovine mastitis, and invasion of bovine mammary cells (MAC-T). To determine minimum inhibitory concentration, we used the broth dilution method, using CDO concentrations range from 0.0125 to 0.4% with 2-fold dilutions. Growth inhibition was examined by adding 0.00, 0.05, 0.025, 0.0125, and 0.00625% CDO to 10(5) cfu/mL S. aureus in nutrient broth and enumerating colonies after serial dilution. In a 96-well plate, S. aureus (10(7) cfu/mL) was allowed to form a biofilm, treated with 0, 0.025, 0.5, or 1% CDO, and then was measured using a spectrophotometer. Cytotoxic effect on immortalized MAC-T cells was also examined at various concentrations of CDO using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. We observed that the minimum inhibitory concentration of CDO to inhibit the growth of S. aureus in vitro was 0.025% CDO. A time kill curve for CDO action on S. aureus over 4 h was generated. The CDO completely eliminated S. aureus after 3 h of incubation at a concentration of 0.25%, or after 2 h of incubation at concentrations of 0.05%. It was also observed that CDO had no effect on preformed biofilms except at a concentration of 0.05%, in which a significant reduction in the measured absorbance was noted. In addition, the association and invasion of S. aureus to MAC-T cells were significantly inhibited after 1 h of treatment with CDO. Citrus-derived oil was also able to increase cellular proliferation of MAC-T cells at concentrations up 0.05% and had no effect at a concentration of 0.1% after 1 h. Our data suggests that CDO should be considered for further research as a preventive and therapeutic against bovine mastitis.
The present review attempts to address the emergence of a fast-growing mastitis causing pathogen – coagulase-negative staphylococci (CNS) – and its multi-facet roles in dairy farms. CNS is divided into numerous species, but only a few succeed in bovine mastitis. The two predominant CNS species causing mastitis are Staphylococcus chromogenes and Staphylococcus simulans . These two mostly known CNS affects dairy cows at varied parities and at different lactation stages. CNS have been judged to be the most common bovine mastitis isolate in several countries of the world. However, CNS may not likely be as pathogenic as the other primary mastitis pathogens such as Staphylococcus aureus and its infection mostly remains subclinical. Conversely, CNS is capable of triggering persistent infections among dairy herds, resulting in reduced milk quality and high milk somatic cell count (SCC). One negative impact of CNS infection in dairy herds is that it can destroy cow udder tissue, hereby leading to a drop in milk production of dairy cows. CNS mastitis has a high cure rate when treated with anti-biotics as their infection in cows are not known to be a therapeutic problem. Judging from several literatures, it cannot be said whether CNS species act as an ecological or contagious pathogens. Regulator procedures, including pre- and post-milking teat disinfection, may reduce contagious mastitis pathogens of CNS infections in the dairy herd. Phenotypic methods for identification of CNS are not adequately dependable, and molecular techniques of identification may be better substitute for identification. Dairy farmers may benefit greatly from more empirical research on the epidemiology of CNS mastitis and more reliable methods for species identification.
Bovine mastitis is one of the biggest concerns in the dairy industry, where it affects sustainable milk production, farm economy and animal health. Most of the mastitis pathogens are bacterial in origin and accurate diagnosis of them enables understanding the epidemiology, outbreak prevention and rapid cure of the disease. This thesis aimed to provide a diagnostic solution that couples Matrix-Assisted Laser Desorption/Ionization-Time of Flight (MALDI-TOF) mass spectroscopy coupled with machine learning (ML), for detecting bovine mastitis pathogens at the subspecies level based on their phenotypic characters. In Chapter 3, MALDI-TOF coupled with ML was performed to discriminate bovine mastitis-causing Streptococcus uberis based on transmission routes; contagious and environmental. S. uberis isolates collected from dairy farms across England and Wales were compared within and between farms. The findings of this chapter suggested that the proposed methodology has the potential of successful classification at the farm level. In Chapter 4, MALDI-TOF coupled with ML was performed to show proteomic differences between bovine mastitis-causing Escherichia coli isolates with different clinical outcomes (clinical and subclinical) and disease phenotype (persistent and non-persistent). The findings of this chapter showed that phenotypic differences can be detected by the proposed methodology even for genotypically identical isolates. In Chapter 5, MALDI-TOF coupled with ML was performed to differentiate benzylpenicillin signatures of bovine mastitis-causing Staphylococcus aureus isolates. The findings of this chapter presented that the proposed methodology enables fast, affordable and effective diag-nostic solution for targeting resistant bacteria in dairy cows. Having shown this methodology successfully worked for differentiating benzylpenicillin resistant and susceptible S. aureus isolates in Chapter 5, the same technique was applied to other mastitis agents Enterococcus faecalis and Enterococcus faecium and for profiling other antimicrobials besides benzylpenicillin in Chapter 6. The findings of this chapter demonstrated that MALDI-TOF coupled with ML allows monitoring the disease epidemiology and provides suggestions for adjusting farm management strategies. Taken together, this thesis highlights that MALDI-TOF coupled with ML is capable of dis-criminating bovine mastitis pathogens at subspecies level based on transmission route, clinical outcome and antimicrobial resistance profile, which could be used as a diagnostic tool for bo-vine mastitis at dairy farms.
Non-aureus staphylococci (NAS) and Staphylococcus aureus are pathogens that cause bovine mastitis, a costly disease for dairy farmers, however; many NAS are considered part of the normal udder microbiota. It has been suggested that through a mechanism that remains to be elucidated, NAS intramammary colonization can prevent subsequent infection with other bacterial pathogens. This study shows that in a murine mastitis model, secondary Staph. aureus intramammary colonization is reduced by exoproducts from Staph. chromogenes and Staph. simulans, both NAS, while Streptococcus spp. exoproducts have much less ability to affect the course of the infection caused by S. aureus.
Mastitis is the economically most important disease of dairy cows. This study used PacBio single-molecule real-time sequencing technology to sequence the full-length 16S rRNAs from 27 milk samples (18 from mastitis and nine from healthy cows; the cows were at different stages of lactation). We observed that healthy or late stage milk microbiota had significantly higher microbial diversity and richness. The community composition of the microbiota of different groups also varied greatly. The healthy cow milk microbiota was predominantly comprised of Lactococcus lactis, Acinetobacter johnsonii, and Bacteroides dorei, while the milk from mastitis cows was predominantly comprised of Bacillus cereus. The prevalence of L. lactis and B. cereus in the milk samples was confirmed by digital droplets PCR. Differences in the milk microbiota diversity and composition could suggest an important role for some these microbes in protecting the host from mastitis while others associated with mastitis. The results of our research serve as useful references for designing strategies to prevent and treat mastitis.
In dairy industry, quality of produced milk must be more important than quantity without a high somatic cells count (SCC) or pathogens causing mastitis of dairy cows and consumer diseases. Preserving the good health of dairy cows is a daily challenge for all involved in primary milk production. Despite the increasing level of technological support and veterinary measures, inflammation of the mammary gland–mastitis, is still one of the main health problems and reasons for economic losses faced by cow farmers. The mammary gland of high-yielding dairy cows requires making the right decisions and enforcing the proper measures aimed at minimizing external and internal factors that increase the risk of intramammary infection. Due to the polyfactorial nature of mastitis related to its reduction, the effectiveness of commonly used antimastitis methods tends to be limited and therefore it is necessary to find the areas of risk in udder health programs and monitoring systems. Only by implementing of complete udder health programs should be accompanied by research efforts to further development these complete udder health control. The present review analyses the current knowledge dealing with damping and prevention of mastitis include SCC control, proper nutrition, housing and management, milking and drying as practiced in dairy farming conditions. This information may help to improve the health of the mammary gland and the welfare of the dairy cows as well as the production of safe milk for consumers.
Bovine mastitis is the most frequent disease in dairy herds worldwide. This disease causes great
economic losses to producers, industry and consumers, since there are direct implications in public
health due to the zoonotic potential of some agents involved in its etiology and the presence of
antimicrobial residues in milk. Considering the multifactorial aspect of the disease and the importance
of milk production in family farming, knowledge of the agents involved in its etiology and the
susceptibility profiles to antimicrobials is of paramount importance. In this study, the prevalence of
Staphylococcus aureus and Streptococcus agalactiae in herds of family farms in the Campo das
Vertentes region of Minas Gerais State, and the resistance of these pathogens to the antibiotics most
commonly used in the treatment of mastitis in livestock dairy farmers were evaluated. The study
involved 200 properties, covering an area of approximately 12,564 km2. The prevalences of
pathogens were carried out through microbiological analyzes of milk samples from the bulk milk tank.
The modified Baird-Parker Agar medium was used for the detection of S. aureus, and the modified
Edwards Agar medium, enriched with 5% desfibrinated sheep blood was used for the detection of S.
agalactiae. Disc diffusion technique was used to evaluate resistance to antibiotics. The results showed
high prevalence of S. aureus pathogens (71.0%) and S. agalactiae (68.0%) in the farms studied with
high levels of resistance and multidrug resistance. The results demonstrate that there are control
failures measures to contagious mastitis in studied herds, pointing to the need for more effective
control these pathogens and the more judicious use of antibiotics aiming to minimize the problem of
resistance to them.
Existen dos aspectos muy importantes para todo ganadero o profesional vinculado al sector productor lechero, y nos referimos al incremento en la producción de leche lo que
conlleva al aumento de la mastitis bovina, estos aspectos van ligados entre sí. La salud de la ubre, es determinante para el buen desempeño bioproductivo de las hembras
bovinas, principalmente en las razas especializadas en la producción de leche. Se considera a la mastitis como el padecimiento más frecuente y costoso a nivel de las unidades de Producción Animal del ganado bovino para leche debido a sus graves pérdidas económicas ocasionadas por la disminución en la cantidad y calidad de la leche producida. La baja rentabilidad que ocasiona esta enfermedad es principalmente por la disminución en la producción de leche, el alto costo de los tratamientos, la leche de descarte, la mano de obra extra para el manejo y desinfección de los equipos y el seguimiento veterinario de animales afectados, entre otros aspectos que hacen de ésta patología un verdadero problema en la ganadería lechera. El objetivo de este capítulo es dar a conocer al lector sobre la importancia de la mastitis bovina en el campo de la producción de leche y la influencia que esta tiene en la economía pecuaria.
The aim of this study was to compare the efficacy of two dry-off protocols: (a) dry cow therapy using ciprofloxacin hydrochloride 400 mg followed by the administration of an internal teat sealant composed of 4 g of bismuth subnitrate, and (b) a positive control using dry cow therapy with 250 mg cephalonium followed by the administration of 2.6 g bismuth subnitrate internal teat sealant. A total of 578 Holstein cows selected from 7 commercial herds were randomly allocated into two groups at drying off: (a) ciprofloxacin hydrochloride 400 mg (CH) associated with ITS, n = 1112 mammary quarters/296 cows, or (b) positive control (PC) = cephalonium (250 mg) associated with ITS, n = 1058 mammary quarters/282 cows). A total of 1787 out of 2170 mammary quarters (82%) had negative culture at drying off. The microorganisms most frequently isolated at drying off were CNS (5.62%), Strep. uberis (1.9%), Corynebacterium spp. (1.8%), and Staphylococcus aureus (1.01%). A total of 465 mammary quarters experienced new intramammary infections (NIMIs), and the main microorganisms causing NIMI were CNS (21.94%), Strep. uberis (17.2%), and Pseudomonas spp. (9.7%). The CH protocol was not inferior to PC, as the cure risk of mammary quarters CH-treated was at the noninferiority limit. However, the mammary quarters treated by CH protocol had 24% and 31% lower risk of overall NIMI and NIMI caused by major pathogens, respectively, than mammary quarters dried with the PC protocol. In addition, the mammary quarters treated with CH protocol had a lower risk of CM through the first 60 DIM than those treated with PC protocol. Both DCT protocols showed similar odds of microbiological cure, but the CH protocol had greater prevention against NIMI during dry-off period.
Nowadays udder inflammation, referred to as mastitis, is one of the biggest issues for milk producers. This disease causes significant economic losses and has a negative impact on cows’ yields, their welfare, as well as milk composition and technological properties. Mastitis may be caused by several pathogens belonging to bacterial species (e.g. Streptococcus uberis, Streptococcus dysgalactiae, Escherichia coli, Enterococcus spp. and Pseudomonas spp.), fungi (e.g. Candida spp. or Cryptococcus spp.) or algae (e.g. Prototheca). However, staphylococci (e.g. Staphylococcus aureus, Staphylococcus epidermidis) are some of the most common mastitis bacterial pathogens. Available information concerning the most frequent species involved in staphylococcal mastitis is reviewed in this paper.
Mastitis, which is caused by infection of the mammary gland is the most important disease problem facing dairy farmers. While the disease has been studied for decades in order to determine better diagnosis and treatment, it is only recently that the full panoply of advanced biotechnological methodologies has been applied that are needed to bring a systems biology approach to investigations. Molecular investigations using analyte-specific immunoassays, such as for the acute phase proteins haptoglobin and mammary-associated serum amyloid A3 in milk have introduced possibilities for monitoring the host inflammatory response. The omics revolution in biology, with genomics being harnessed especially for identification of the causative pathogens of mastitis, has enhanced dissection of the mammary microbiome. The application of proteomics, peptidomics and metabolomics to the diagnosis and pathophysiology of mastitis, in contrast, is in its infancy though the potential of these advanced tools of biological research is clear as they are applied in a systems biology analysis of this major health problem of dairy cows.
Introduction. Zoonoses have been controlled in high-income countries, while low- and middle-income countries make efforts with strategies that reduce the burden of the disease. Health interventions (human, animal and environmental) contribute to building trust, community commitment and intersectoral collaboration, and strengthen the capacity of health systems to respond to zoonoses. Objective. Analyze comparatively the national initiatives against zoonoses, according to the income (IMF) of the countries of Latin America and the Caribbean. Methods A search was made of national initiatives against zoonoses in high, medium-high, medium-low and low-income countries in Latin America and the Caribbean. A comparative matrix was built and analyzed, identifying the characteristics and content of national initiatives. The monitoring of the events and the measures executed by country was analyzed according to their income. Results The ranking of 19 countries in Latin America and the Caribbean according to their income is: high, 1 ;, medium high, 12; medium low, 5, and low, 1. The initiatives were classified into: manuals, 2; programs, 9; laws, 1; norms, 3; regulations, 1; several, 1, and information not available, 2. The common objective is to establish actions against zoonoses, developed to reduce morbidity and mortality, strengthen epidemiological surveillance, strengthen national capacity, develop institutional mechanisms and generate synergies. The monitored events were classified as: viral, 8; bacterial, 8; parasitic, 7; bite by poisonous animals, 2, and responsible animal ownership, 2. Countries, regardless of income, include five measures: promotion, prevention, diagnosis, monitoring and control. Conclusion. The programs have the largest proportion, which include activities to control zoonoses, their analysis and research. Due to geographical position, climatic variety and biological diversity, surveillance focuses on rabies, leptospirosis and toxoplasmosis. The actions of cooperation, intersectoriality and transversality implemented from the state instances, according to competence, and society, contribute with the objectives set out in the initiatives against the zoonoses.
Using a natural exposure trial design, the goal of our
study was to evaluate the clinical efficacy of an iodine
teat disinfectant with barrier properties and a high
level of free iodine relative to a conventional iodine teat
disinfectant with no barrier properties and low levels of
free iodine. During the 18 wk of the trial, quarter milk
samples were collected every 2 wk from 385 dairy cows
from 2 herds. Cows on both farms were assigned in a
balanced way according to milk yield, number of lactation,
days in milk, somatic cell count (SCC) and microbiology
culture pretrial into one of following groups:
nonbarrier post milking teat disinfectant (NBAR; n
= 195 cows; 747 quarters) or barrier postmilking teat
disinfectant (BAR; n = 190 cows; 728 quarters). Afterward,
at each scoring date every 2 wk, milk SCC was
quantified in samples from all mammary quarters and
microbiologic culture was only performed on milk samples
with SCC >200,000 cells/mL for multiparous cows
and SCC >100,000 cells/mL for primiparous cows. A
new intramammary infection (NIMI) was defined when
a quarter had milk SCC <200,000 cells/mL for multiparous
cows and <100,000 cells/mL for primiparous
without microorganism isolation; NIMI was also defined
as a subsequent sampling visit with milk SCC >200,000
cells/mL for multiparous cows and >100,000 cells/mL
for primiparous cows along with positive microorganism
isolation. A quarter could have several NIMI, but
only 1 case per specific pathogen was considered. The
most frequently isolated microorganism group on both
farms was Streptococcus spp. (6.25% of total mammary
quarters), followed by coagulase-negative staphylococci
(3.6%) and Corynebacterium spp. (1.5%). In the present
study, an interaction occurred between treatment
and week of trial on the incidence risk of NIMI. Quarters
disinfected with BAR had 54 and 37% lower odds
of NIMI than quarters disinfected with NBAR at 8 and
16 wk of the trial, respectively; whereas at other weeks
of the study both products had similar incidence risks
of NIMI. Overall, teats disinfected with BAR had 46%
lower odds of acquiring a clinical mastitis than those
disinfected with NBAR. We concluded that the postmilking
teat disinfectant with barrier properties and
higher free iodine content reduced the risk of clinical
mastitis, although differences in new infections were
detected at only weekly time points.
A longitudinal study in 3 dairy herds was conducted to profile the distribution of coagulase-negative Staphylococcus (CNS) species causing bovine intramammary infection (IMI) using molecular identification and to gain more insight in the pathogenic potential of CNS as a group and of the most prevalent species causing IMI. Monthly milk samples from 25 cows in each herd as well as samples from clinical mastitis were collected over a 13-mo period. Coagulase-negative staphylococci were identified to the species level using transfer-RNA intergenic spacer PCR. The distribution of CNS causing IMI was highly herd-dependent, but overall, Staphylococcus chromogenes, Staphylococcus xylosus, Staphylococcus cohnii, and Staphylococcus simulans were the most prevalent. No CNS species were found to cause clinical mastitis. The effect of the most prevalent species on the quarter milk somatic cell count (SCC) was analyzed using a linear mixed model, showing that Staph. chromogenes, Staph. simulans, and Staph. xylosus induced an increase in the SCC that is comparable with that of Staphylococcus aureus. Almost all CNS species were able to cause persistent IMI, with Staph. chromogenes causing the most persistent infections. In conclusion, accurate species identification cannot be ignored when studying the effect of CNS on udder health, as the effect on SCC differs between species and species distribution is herd-specific. Staphylococcus chromogenes, Staph. simulans, and Staph. xylosus seem to be the more important species and deserve special attention in further studies. Reasons for herd dependency and possible cow- and quarter-level risk factors should be examined in detail for the different species, eventually leading to cost-benefit analyses for management changes and, if needed, treatment recommendations.
Criteria for diagnosing intramammary infections (IMI) have been debated for many years. Factors that may be considered in making a diagnosis include the organism of interest being found on culture, the number of colonies isolated, whether or not the organism was recovered in pure or mixed culture, and whether or not concurrent evidence of inflammation existed (often measured by somatic cell count). However, research using these criteria has been hampered by the lack of a "gold standard" test (i.e., a perfect test against which the criteria can be evaluated) and the need for very large data sets of culture results to have sufficient numbers of quarters with infections with a variety of organisms. This manuscript used 2 large data sets of culture results to evaluate several definitions (sets of criteria) for classifying a quarter as having, or not having an IMI by comparing the results from a single culture to a gold standard diagnosis based on a set of 3 milk samples. The first consisted of 38,376 milk samples from which 25,886 triplicate sets of milk samples taken 1 wk apart were extracted. The second consisted of 784 quarters that were classified as infected or not based on a set of 3 milk samples collected at 2-d intervals. From these quarters, a total of 3,136 additional samples were evaluated. A total of 12 definitions (named A to L) based on combinations of the number of colonies isolated, whether or not the organism was recovered in pure or mixed culture, and the somatic cell count were evaluated for each organism (or group of organisms) with sufficient data. The sensitivity (ability of a definition to detect IMI) and the specificity (Sp; ability of a definition to correctly classify noninfected quarters) were both computed. For all species, except Staphylococcus aureus, the sensitivity of all definitions was <90% (and in many cases<50%). Consequently, if identifying as many existing infections as possible is important, then the criteria for considering a quarter positive should be a single colony (from a 0.01-mL milk sample) isolated (definition A). With the exception of "any organism" and coagulase-negative staphylococci, all Sp estimates were over 94% in the daily data and over 97% in the weekly data, suggesting that for most species, definition A may be acceptable. For coagulase-negative staphylococci, definitions B (2 colonies from a 0.01-mL milk sample) raised the Sp to 92 and 95% in the daily and weekly data, respectively. For "any organism," using definition B raised the Sp to 88 and 93% in the 2 data sets, respectively. The final choice of definition will depend on the objectives of study or control program for which the sample was collected.
This study was designed to identify risk factors for intramammary infections with Streptococcus uberis and Staphylococcus aureus under field conditions. An 18-mo survey with sampling of all quarters of all lactating cows at 3-wk intervals was carried out in three Dutch dairy herds with medium bulk milk somatic cell count (200,000 to 300,000 cells/ml). Quarter milk samples were used for bacteriology and somatic cell counting. Data on parity, lactation stage, and bovine herpesvirus 4-serology were recorded for each animal. During the last year of the study, body condition score, and teat-end callosity scores were recorded at 3-wk intervals. A total of 93 new infections with Strep. uberis were detected in 22,665 observations on quarters at risk for Strep. uberis infection, and 100 new infections with Staph. aureus were detected in 22,593 observations on quarters at risk for Staph. aureus infection. Multivariable Poisson regression analysis with clustering at herd and cow level was used to identify risk factors for infection. Rate of infection with Strep. uberis was lower in first- and second-parity cows than in older cows, and depended on stage of lactation in one herd. Quarters that were infected with Arcanobacterium pyogenes or enterococci, quarters that had recovered from Strep. uberis- or Staph. aureus-infection in the past, and quarters that were exposed to another Strep. uberis infected quarter in the same cow had a higher rate of Strep. uberis infection. Teat-end callosity and infection with coagulase-negative staphylococci or corynebacteria were not significant as risk factors. Rate of Staph. aureus infection was higher in bovine herpesvirus 4-seropositive cows, in right quarters, in quarters that had recovered from Staph. aureus or Strep. uberis infection, in quarters exposed to other Staph. aureus infected quarters in the same cow, and in quarters with extremely callused teat ends. Infection with coagulase-negative staphylococci was not significant as a risk factor. The effect of infection with corynebacteria on rate of infection with Staph. aureus depended on herd, stage of lactation, and teat-end roughness. Herd level prevalence of Strep. uberis or Staph. aureus, and low quarter milk somatic cell count were not associated with an increased rate of infection for Strep. uberis or Staph. aureus.
This article describes an updated version of the metabias command, which provides statistical tests for funnel plot asymmetry. In addition to the previously implemented tests, metabias implements two new tests that are recom- mended in the recently updated Cochrane Handbook for Systematic Reviews of Interventions (Higgins and Green 2008). The first new test, proposed by Harbord, Egger, and Sterne (2006, Statistics in Medicine 25: 3443–3457), is a modified ver- sion of the commonly used test proposed by Egger et al. (1997, British Medical Journal 315: 629–634). It regresses Z/√V against √V , where Z is the efficient score and V is Fisher’s information (the variance of Z under the null hypothesis). The second new test is Peters’ test, which is based on a weighted linear regression of the intervention effect estimate on the reciprocal of the sample size. Both of these tests maintain better control of the false-positive rate than the test proposed by Egger at al., while retaining similar power. Copyright 2009 by StataCorp LP.
The primary purpose of this study was to develop a set of criteria to serve as a pseudo-gold standard for what constitutes an intramammary infection using data from 3 consecutive quarter milk samples taken 1 wk apart. Data from lactating cows in 90 dairy herds in 4 Canadian provinces were used to generate the data sets (profiles) used in the conjoint analysis to elicit expert opinions on the topic. The experts were selected from the participants (n=23) in the 2007 Mastitis Research Workers' Conference in Minneapolis and from a series of mastitis laboratory courses for bovine practitioners (n=25) in the Netherlands. Three-week udder quarter profiles with specific combinations of somatic cell count, bacterial species isolated, and plate colony count were selected and included in the conjoint analysis based on the desire to achieve even distributions in the categories of 6 constructed variables. The participants were presented with 3 sets of cards with 20 cards in each set. On each card, they were asked to assign a probability of infection on the middle day (test day) in the 3-wk profile. Depending on the set of cards, they were asked only to be concerned with the probability of infection with coagulase-negative staphylococci, Escherichia coli, or Staphylococcus aureus. These 3 organisms were chosen to represent a minor pathogen, a major environmental pathogen, and a major contagious pathogen, respectively. The assigned probabilities for each organism were cross-tabulated according to the number of times the organism of interest was isolated in the 3-wk period, how many colonies of the organism of interest were isolated on the test day, and the somatic cell count (<or= or >200,000 cells/mL). There was considerable variation in the assigned probabilities within each of the combinations of factors. The median, minimum, and maximum values of the assigned probabilities for each combination were computed. The combinations with a median probability >50% were considered intramammary infection-positive and included as a criterion in the consensus standard. This yielded 4 possible criteria, which were condensed to the following 2 by consensus at the 2008 Mastitis Research Workers' Conference in Toronto: 1) the organism of interest was isolated on the test day with at least 10 colonies (1,000 cfu/mL), and 2) the organism of interest was isolated at least twice in the 3-wk period.
We present a revised version of the metareg command, which performs meta-analysis regression (meta-regression) on study-level summary data. The major revisions involve improvements to the estimation methods and the addition of an option to use a permutation test to estimate p-values, including an adjustment for multiple testing. We have also made additions to the output, added an option to produce a graph, and included support for the predict command. Stata 8.0 or above is required. Copyright 2008 by StataCorp LP.
Coagulase-negative staphylococci (CNS) have become the most common bovine mastitis isolate in many countries and could therefore be described as emerging mastitis pathogens. The prevalence of CNS mastitis is higher in primiparous cows than in older cows. CNS are not as pathogenic as the other principal mastitis pathogens and infection mostly remains subclinical. However, CNS can cause persistent infections, which result in increased milk somatic cell count (SCC) and decreased milk quality. CNS infection can damage udder tissue and lead to decreased milk production. Staphylococcus simulans and Staphylococcus chromogenes are currently the predominant CNS species in bovine mastitis. S. chromogenes is the major CNS species affecting nulliparous and primiparous cows whereas S. simulans has been isolated more frequently from older cows. Multiparous cows generally become infected with CNS during later lactation whereas primiparous cows develop infection before or shortly after calving. CNS mastitis is not a therapeutic problem as cure rates after antimicrobial treatment are usually high. Based on current knowledge, it is difficult to determine whether CNS species behave as contagious or environmental pathogens. Control measures against contagious mastitis pathogens, such as post-milking teat disinfection, reduce CNS infections in the herd. Phenotypic methods for identification of CNS are not sufficiently reliable, and molecular methods may soon replace them. Knowledge of the CNS species involved in bovine mastitis is limited. The dairy industry would benefit from more research on the epidemiology of CNS mastitis and more reliable methods for species identification.
The epidemiology and importance of coagulase negative staphylococcal (CNS) mastitis in Prince Edward Island had not been documented. To investigate this, a cohort of 84 cows at seven farms were quarter sampled eight times over a lactation, commencing with samples taken prior to drying off in the previous lactation. Thirteen species of CNS were isolated. The quarter prevalence of CNS mastitis varied from 4.8% to 6.4% in the first five months of lactation and increased to 14.2 to 16.6% in the last four months of lactation. The geometric mean somatic cell counts (SCC) for quarters infected with CNS and uninfected quarters were 90 x 10(3) and 64 x 10(3) respectively (difference significant at p > 0.005). The two month new infection risk of CNS was 9.0% while the two month elimination risk was 74.4%. Infection with CNS did not alter the risk of subsequent infection with Staphylococcus aureus. The results from this project support the classification of CNS as a minor pathogen in mastitis control programs.
New mammary infections were recorded in 3 dairy herds during a lactation period by bacteriologic examination of milk samples at 3-week intervals. Influences of the infection status of quarters at the time of new infection and of microorganisms responsible for bacterial invasion were analyzed. The new infection rate in uninfected quarters was about 3 times the rate in quarters already harboring bacterial considered minor pathogens (coagulase-negative staphylococci and Corynebacterium bovis) or major pathogens (Staphylococcus aureus, streptococci). The frequency of new infections with major pathogens was almost halved by preexisting infections with minor pathogens (P = 0.05), mainly because of coagulase-negative staphylococci (P = 0.05) and, to a lesser extent, C bovis (P = 0.19). New infections by minor pathogens also were less frequent in quarters harboring a major pathogen (P less than 0.05), indicating that the competition or antagonism between mammary infections was a general phenomenon.
The purpose of this study was to identify factors at the quarter and cow level that determine whether a quarter remains infected after an intramammary challenge with Staphylococcus aureus Newbould 305. A total of 135 cows were studied. Information on animal characteristics, cow-conformation, cow somatic cell count (SCC), and bacteriology, blood vitamin E levels, serology for retro-viral infections, bovine leukocyte adhesion deficiency-carrier status, and the presence of bovine lymphocyte antigens class I alleles was collected on each animal. All quarters of all cows were then challenged with Staphylococcus aureus Newbould 305. The challenge with S. aureus Newbould 305 resulted in 28 cows (20.7%) that did not establish infection in any of the quarters, 21 (15.6%) cows had 1 quarter infected, 35 (25.9%) had 2 quarters infected, 24 (17.8%) had 3 quarters infected, and 27 (20.0%) had all quarters infected. A higher prechallenge SCC decreased the risk of infection. An infection with Corynebacterium bovis prior to challenge decreased the risk of S.aureus infection. Of the bovine lymphocyte antigen alleles, the presence of the W20A allele proved to be significantly associated with a decreased risk of infection. No other factors proved to be significant.
An outbreak of Streptococcus uberis mastitis was described to gain insight into the dynamics of Strep. uberis infections at a herd level. Data were obtained from a longitudinal observational study on a commercial Dutch dairy farm with good udder health management. Quarter milk samples for bacteriological culture were routinely collected at 3-wk intervals from all lactating animals (n = 95 +/- 5). Additional samples were collected at calving, clinical mastitis, dry-off, and culling. During the 78-wk observation period, 54 Strep. uberis infections were observed. The majority of infections occurred during a 21-wk period that constituted the disease outbreak. The incidence rate was higher in quarters that had recovered from prior Strep. uberis infection than in quarters that had not experienced Strep. uberis infection before. The incidence rate of Strep. uberis infection did not differ between quarters that were infected with other pathogens compared with quarters that were not infected with other pathogens. The expected number of new Strep. uberis infections per 3-wk interval was described by means of a Poisson logistic regression model. Significant predictor variables in the model were the number of existing Strep. uberis infections in the preceding time interval (shedders), phase of the study (early phase vs. postoutbreak phase), and prior infection status of quarters with respect to Strep. uberis, but not infection status with respect to other pathogens. Results suggest that contagious transmission may have played a role in this outbreak of Strep. uberis mastitis.
Dry cow therapy, or antibiotic treatment at end of lactation, is used to eliminate intramammary infections and prevent new infections during the dry period. It is one part of a total management system recommended in controlling intramammary infections in the dairy cow. Public health concerns advise prudent use of antibiotics, as their use may promote bacterial antibiotic resistance and leave antibiotic residues in the food chain. The effects of dry cow treatment and no treatment were compared, on new intramammary infections and clinical mastitis within two low cell count herds and two herds undergoing conversion to organic farming. The results will inform those restricting their use of dry cow therapy on the additional risk of new intramammary infection and aid in development of alternative management strategies. No cases of clinical mastitis in the dry period were observed in treated cows, whereas in the untreated groups a significant number were observed. Significantly more new infections at calving were found in the untreated group in all herds. In those quarters where infections were first detected at calving, the incidence of clinical mastitis was significantly greater in the untreated group in all herds. Clinical mastitis detection was significantly lower in organic herds. Untreated quarters infected at drying with Corynebacterium spp. or coagulase-negative staphylococci were found to have an increased risk of new infection by Streptococcus uberis or coliform bacteria. It can be concluded that dry cow therapy continues to lower significantly the rate of new dry period intramammary infection in herds with elevated somatic cell counts and a high prevalence of infection.
As concern over the possible overuse of antibacterials increases, attention has focused on reduction of antibiotic usage and on nonantibiotic alternatives. A nonantibiotic intramammary teat sealant, Teat Seal (Cross Vetpharm Group Ltd., Tallaght, Dublin, Ireland), has been available in Ireland, in combination with an intramammary tube of cloxacillin. Teat Seal has been reformulated for use in cows with low cell counts as an alternative to antibiotic dry cow therapy at the end of lactation. The product is now marketed as Orbeseal (Pfizer Animal Health). A comparison between this teat sealant and no treatment was made on new intramammary infections and clinical mastitis, on all cows within four herds, and on low cell count cows in three herds. No cases of clinical mastitis in the dry period were observed in cows treated with Teat Seal (n = 197), whereas a significant number (6 cows) were observed in the untreated cows (n = 204). In all herds, significantly more new infections at calving were found in the untreated group (62 cows in the untreated group compared with 21 cows in the Teat Seal group). In those quarters where infections were first detected at calving, the incidence of clinical mastitis was significantly greater in the untreated group. Quarters in both treatment groups that were infected at drying off with Corynebacterium spp. or coagulase-negative staphylococci were not protected against new infections and had an increased risk of new infection by Streptococcus uberis. The results will inform those restricting their use of antibiotic dry cow therapy in alternative management strategies and the additional risk of new intramammary infection.
To assess the prevalence and patterns of bacterial isolates, cultures were made from the dry mammary glands of dairy cows in six commercial dairy herds in the UK. Milk samples were taken from all four quarters of 480 cows at drying off and at weekly intervals from 14 days before to seven days after calving. A major mastitis pathogen was isolated from at least one quarter of 220 (45.8 per cent) of the cows and from more than one quarter of 90 (18.8 per cent) of them. During the late dry to calving period, of the 957 quarters with three culture results, a major mastitis pathogen was cultured from 236 (24.7 per cent) quarters of 186 (38.8 [corrected] per cent) cows. The most commonly isolated major pathogen was Escherichia coli, followed by Streptococcus uberis and coagulase-positive staphylococci. There were significant differences between the patterns of isolates from different farms and in different calving months, suggesting that the rate of infection was partially dependent on external conditions. The isolation of E. coli, S. uberis or coagulase-positive staphylococci from a cow during the late dry/periparturient period was associated with an increased risk of that cow being culled in the next lactation. Bayesian general linear mixed models were used to assess the associations between the different bacterial species. The probability of isolating either E. coli or S. uberis was significantly greater when the other organism was cultured in a milk sample; this was also true of coagulase-positive staphylococci and S. uberis. When Corynebacterium species were isolated from a milk sample, the probability of isolating coagulase-positive staphylococci or S. uberis decreased significantly, and when coagulase-negative staphylococci were isolated the probability of isolating coagulase-positive staphylococci was reduced.
Infection of the bovine mammary gland with Streptococcus uberis currently accounts for around 33% of all clinical cases of mastitis in the UK3. S. uberis can attain cell densities of 108 cfu/ml in vivo 2 in an environment were the availability of free amino acids and peptides is potentially growth limiting1. However, little is known of the physiology or biochemistry of either the nutrient requirements of S. uberis or the routes by which essential nutrients may be acquired. The ability of auxotrophic bacteria to grow in mastitic milk is enhanced by the presence of the caseinolytic enzyme plasmin6. S. uberis is also capable of activating bovine plasminogen to plasmin5.
Small volumes of milk each containing an average of less than 10 colonyforming units of Staphylococcus aureus were injected into the teat cisterns of 39 quarters of 10 cows.
Typical staphylococci were recovered from only 14 quarters following overnight incubation of milk stripped manually from each quarter 10 min after injection. There was an inverse relationship between the total leucocyte count of the milk taken from the quarter before infusion and recovery of staphylococci.
From 4 of 8 quarters from which Staph. aureus could not be recovered by enrichment it was possible to recover the organism by centrifuging the milk and culturing the deposit of leucocytes and bacteria.
It is suggested that release of ingested staphylococci from defunct phagocytes may be important in initiation of infection, failure of antibiotic therapy and recurrence of infection.
Major mastitis pathogens such as Staphylococcus aureus, Streptococcus uberis, Streptococcus dysgalactiae, and coliforms are usually considered more virulent and damaging to the udder than minor mastitis pathogens such as Corynebacterium spp. and coagulase-negative staphylococci (CNS). The current literature comprises several studies (n=38) detailing analyses with conflicting results as to whether intramammary infections (IMI) with the minor pathogens decrease, increase, or have no effect on the risk of a quarter acquiring a new IMI (NIMI) with a major pathogen. The Canadian Bovine Mastitis Research Network has a large mastitis database derived from a 2-yr data collection on a national cohort of dairy farms, and data from this initiative were used to further investigate the effect of IMI with minor pathogens on the acquisition of new major pathogen infections (defined as a culture-positive quarter sample in a quarter that had been free of that major pathogen in previous samples in the sampling period). Longitudinal milk samplings of clinically normal udders taken over several 6-wk periods as well as samples from cows pre-dry-off and postcalving were used to this end (n=80,397 quarter milk samples). The effects of CNS and Corynebacterium spp. on the major mastitis pathogens Staph. aureus, Strep. uberis, Strep. dysgalactiae, and coliform bacteria (Escherichia coli and Klebsiella spp.) were investigated using risk ratio analyses and multilevel logistic regression models. Quarter-, cow- and herd-level susceptibility parameters were also evaluated and were able to account for the increased susceptibility that exists within herds, cows and quarters, removing it from estimates for the effects of the minor pathogens. Increased quarter-level susceptibility was associated with increased risk of major pathogen NIMI for all pathogens except the coliforms. Increased somatic cell count was consistently associated with elevated risk of new major pathogen infections, but this was assumed to be a result of low sensitivity of bacteriology to diagnose major pathogen NIMI expediently and accurately. The presence of CNS in the sample 2 samplings before the occurrence of a NIMI increased the odds of experiencing a Staph. aureus NIMI 2.0 times, making the presence of CNS a risk factor for acquiring a Staph. aureus NIMI. Even with this extensive data set, power was insufficient to make a definitive statement about the effect of minor pathogen IMI on the acquisition of major pathogen NIMI. Definitively answering questions of this nature are likely to require an extremely large data set dedicated particularly to minor pathogen presence and NIMI with major pathogens.
The association between the contagious Staphylococcus aureus genotype B (GTB) and the presence of coagulase-negative staphylococci (CNS) and Streptococcus spp. (non-agalactiae streptococci), was investigated, and the identification of problem herds without genotyping was evaluated. Milk samples from 10 herds with Staph. aureus GTB herd problems (PH cases) were compared with samples from 19 herds with at least one Staph. aureus isolate of non-B genotype (CH cases). All samples were bacteriologically analysed and Staph. aureus genotyping carried out using a ribosomal spacer-PCR. Cow and quarter prevalences of Staph. aureus, CNS and Streptococcus spp. differed significantly between PH and CH groups. PH cases were highly associated with decreased cow prevalences of CNS and Streptococcus spp. These altered prevalences also contributed significantly to the identification of problem herds without resorting to genotyping. Common herd-level risk factors did not explain the difference between the prevalences in PH and CH cases.
Using a 'within-cow' experimental design the susceptibility of uninfected or Staphylococcus epidermidis infected udder quarters to challenge with Escherichia coli or Streptococcus agalactiae was measured. Twenty-one Staph. epidermidis infected quarters were challenged by infusion of E. coli into the teat sinus and 13 (61·9%) became infected. Fourteen of 15 uninfected quarters challenged similarly with E. coli became infected (93·3%). When another 20 quarters were challenged with Str. agalactiae, one of nine Staph. epidermidis infected quarters (11·1%) and 10 of 11 uninfected quarters became infected. It is suggested that the increased resistance to infection following Staph. epidermidis infection is due to the raised polymorphonuclear leucocyte content of the milk in these quarters rather than any direct inhibition produced by the Staph. epidermidis.
In a study to develop and define a practical model of bovine mastitis caused by Staphylococcus aureus, induced infections were attempted in 203 bovine mammary glands of 41 cows, using 12 strains of S aureus. Approximately 100 colony-forming units of S aureus in saline solution were injected after milking, and milk samples were collected daily from test glands for 14 days to monitor the progress of infections and inflammatory responses. Relationships were examined for cow-related factors and for various characteristics of the strains of S aureus used to the development of a persistent intramammary infection. A dairy cow that was useful in this model was defined as follows: (1) the 2nd to 7th month in the 1st to 5th lactation; (2) producing milk from all mammary glands that contained less than 6 x 10(5) somatic cells/ml; and (3) having mammary glands that were free of any primary mastitis pathogen, as well as micrococci and Corynebacterium bovis. From the present study, it was not possible to define clearly a strain of S aureus which would be useful in the model, but 5 strains of S aureus were identified as being capable of producing persistent subacute infections with a high degree of repeatability.
Small numbers of Escherichia coli were infused into both lactating and non-lactating udders. Twelve of the 17 lactating quarters infused became infected, and all 12 showed clinical symptoms of udder disease. The 5 lactating quarters which did not become infected all had pre-infusion somatic cell counts greater than 300000 cells/ml milk, whilst all the quarters which became infected had cell counts less than 300000 cells/ml milk. E. coli was subsequently recovered from only 6 of the 16 non-lactating quarters infused. In only 2 of these quarters did clinical infection follow, both quarters being in a cow infused 2 d before calving. The remaining 4 quarters from which E. coli was recovered were all negative within 5 d of infusion. These differences in susceptibility are discussed, particularly with reference to the frequent occurrence of coliform mastitis at and shortly after calving.
Microbiological data from 1123 uninfected quarters and 216 quarters with preexisting coagulase-negative staphylococci infections were analyzed to determine the influence of infection status on subsequent new infection rate. Overall, prevalence of new infections in uninfected quarters was approximately two times that in quarters already harboring a coagulase-negative Staphylococcus infection. New infections by coagulase-negative staphylococci were greater in uninfected quarters than in quarters with preexisting coagulase-negative staphylococci infections. However, no differences were observed between uninfected and infected quarters in number of new infections by major pathogens (Staphylococcus aureus, streptococci, and coliforms). No differences were observed in uninfected or coagulase-negative Staphylococcus-infected quarters in infections with minor pathogens compared with major pathogens. The influence of individual coagulase-negative Staphylococcus species on new infections was also analyzed. However, numbers of existing infections by Staphylococcus species other than Staphylococcus chromogenes were limited. Therefore, the protective capacity of each coagulase-negative Staphylococcus species was difficult to assess. Overall, a significant restriction of bacterial invasion was observed in quarters with a preexisting infection. These results suggest that quarters harboring a coagulase-negative Staphylococcus infection suppress colonization of the mammary gland by mastitis-causing pathogens.
The susceptibility of uninfected or Staphylococcus chromogenes-infected quarters to challenge with Staphylococcus aureus was measured. Seventeen S. chromogenes-infected quarters were challenged by infusion of S. aureus into the teat sinus; 47% (8 of 17) became infected and all 18 uninfected quarters challenged similarly with S. aureus became infected. No differences in daily milk yield were seen between uninfected quarters and S. chromogenes-infected quarters prior to S. aureus infusion. Postinfusion, milk yield for S. aureus-infected, S. chromogenes-infected, and S. chromogenes- and S. aureus-infected quarters differed. Somatic cell counts were elevated in S. chromogenes-infected quarters compared with uninfected quarters prior to S. aureus infusion. Somatic cell counts were not different between S. aureus- and S. chromogenes- and S. aureus-infected quarters postinfusion, but were different for S. chromogenes-infected quarters. Chloride concentrations in S. chromogenes- and S. aureus-infected quarters were different from either S. aureus-infected or S. chromogenes-infected quarters. Staphylococcus aureus colony forming units in quarters with preexisting S. chromogenes infections were lower than S. aureus colony-forming units in previously uninfected quarters. Possible protective mechanisms induced by S. chromogenes against superinfection by S. aureus are discussed.
Quarter milk samples were collected monthly on a selected herd of 80 Ayrshire cows having a high frequency of subclinical mastitis. Analysis of bacterial growth rates in milk showed that whey prepared from infected or inflamed quarters stimulated bacterial growth. Milk N-acetyl-beta-D-glucosaminidase, antitrypsin, and plasmin activities all showed positive correlations with bacterial replication rates (Staphylococcus aureus and Escherichia coli) in respective whey samples as determined by a turbidometric micro-technique. Increased bacterial replication rates in mastitic whey represent an increased yield of the key nutrients for bacteria. Bacterial growth enhancement can be partly explained by proteose-peptone originating from plasmin activation and casein degradation. However, as multiple regression analysis showed that a combination of the predictor variables: antitrypsin, N-acetyl-beta-D-glucosaminidase and plasmin explained enhancement of bacterial growth better than plasmin alone, other factors connected with inflammation should be sought when searching for growth-enhancing facto