Volker Krömker

Volker Krömker
University of Copenhagen · Veterinary and Animal Sciences

Prof. Dr., Dip. ECBHM

About

214
Publications
31,763
Reads
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1,614
Citations
Citations since 2017
93 Research Items
1259 Citations
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2017201820192020202120222023050100150200250300
2017201820192020202120222023050100150200250300
Introduction
Volker Krömker currently works at the Microbiology, Hochschule Hannover. Volker does research in Animal Science and Veterinary Medicine.
Additional affiliations
February 2004 - present
February 2004 - present
Hochschule Hannover
Position
  • Professor (Full)

Publications

Publications (214)
Article
Full-text available
Although Corynebacterium spp. can be regularly associated with subclinical and clinical mastitis cases in dairy cows, knowledge on their reservoirs in dairy farms is sparse. Therefore, samples were collected at 10 visits with 14 day intervals from bedding material (n = 50), drinking troughs (n = 20), different walking areas (n = 60), cow brushes (n...
Article
Treatment of clinical mastitis (CM) contributes to antimicrobial use on dairy farms. Selective treatment of CM based on bacterial diagnosis can reduce antimicrobial use, as not all cases of CM will benefit from antimicrobial treatment, e.g., mild and moderate gram-negative infections. However, impacts of selective CM treatment on udder health and c...
Article
Full-text available
In the context of increasing antimicrobial resistance of microorganisms, there is growing interest in preventing the development and spread of antimicrobial resistance worldwide through the prudent use of antimi-crobials and the reduction in antimicrobial use (AMU). Treatment of mastitis is the main cause for the application of antimicrobial substa...
Article
Full-text available
Severe mastitis can lead to considerable disturbances in the cows’ general condition and even to septicemia and death. The aim of this cross-sectional study was to identify factors associated with the severity of the clinical expression of mastitis. Streptococcus (Str.) uberis (29.9%) was the most frequently isolated pathogen, followed by coliform...
Article
Full-text available
Severe mastitis can lead to considerable disturbances in the cows’ general condition and even to septicemia and death. The aim of this cross-sectional study was to identify factors associated with the severity of the clinical expression of mastitis. Streptococcus (Str.) uberis (29.9%) was the most frequently isolated pathogen, followed by coliform...
Article
Full-text available
Selection and spread of Extended Spectrum Beta-Lactamase (ESBL) -producing Enterobacteriaceae within animal production systems and potential spillover to humans is a major concern. Intramammary treatment of dairy cows with first-generation cephalosporins is a common practice and potentially selects for ESBL-producing Enterobacteriaceae, although it...
Article
Full-text available
As part of the European Network for Optimization of Veterinary Antimicrobial Treatment (ENOVAT), a webinar on the topic “Mastitis Treatment in Lactation” was held, in which eight mastitis experts from different European countries (Spain, The Netherlands, Estonia, Ireland, Poland, Finland, Germany, and Italy) presented their treatment approaches for...
Article
Full-text available
As part of the European Network for Optimization of Veterinary Antimicrobial Treatment (ENOVAT), a webinar on the topic “Mastitis Treatment in Lactation” was held, in which eight mastitis experts from different European countries (Spain, The Netherlands, Estonia, Ireland, Poland, Finland, Germany, and Italy) presented their treatment approaches for...
Article
Full-text available
Corynebacterium spp. are frequently detected in bovine quarter milk samples, yet their impact on udder health has not been determined completely. In this longitudinal study, we collected quarter milk samples from a dairy herd of approximately 200 cows, ten times at 14 d intervals. Bacteriologically, Catalase-positive and Gram-positive rods were det...
Article
Full-text available
Corynebacterium spp. are frequently detected in bovine quarter milk samples, yet their impact on udder health has not been determined completely. In this longitudinal study, we collected quarter milk samples from a dairy herd of approximately 200 cows, ten times at 14 d intervals. Bacteriologically, Catalase-positive and Gram-positive rods were det...
Article
Full-text available
In a cross-sectional study, impact of management in dairy farms on calf mortality rates and prevalence of rotavirus and Cryptosporidium parvum in feces of calves was investigated. Sixty-two commercial dairy herds in Mecklenburg-Western Pomerania, Germany, were stratified selected in 2019. We performed in-person interviews and fecal specimens in sam...
Article
Full-text available
In a cross-sectional study, impact of management in dairy farms on calf mortality rates and prevalence of rotavirus and Cryptosporidium parvum in feces of calves was investigated. Sixty-two commercial dairy herds in Mecklenburg-Western Pomerania, Germany, were stratified selected in 2019. We performed in-person interviews and fecal specimens in sam...
Article
Full-text available
To optimise udder health at the herd level, identifying incurable mastitis cases as well as providing an adequate therapy and culling strategy are necessary. Cows with clinical mastitis should be administered antibiotic medication if it is most likely to improve mammary cure. The somatic cell count (SCC) in milk of the monthly implemented Dairy Her...
Article
Full-text available
To optimise udder health at the herd level, identifying incurable mastitis cases as well as providing an adequate therapy and culling strategy are necessary. Cows with clinical mastitis should be administered antibiotic medication if it is most likely to improve mammary cure. The somatic cell count (SCC) in milk of the monthly implemented Dairy Her...
Article
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The aim of this cross-sectional study was to test whether there is an association between clinical mastitis incidence and variations in dry matter intake in lactating dairy cows. Data were collected and analyzed from two voluntarily participating dairy herds (1,000-1,200 cows) between 2017 and 2018. Lactating cows were assigned to seven "effec-tive...
Article
The foster cow system is an alternative way of calf rearing, where two to four calves are simultaneously nursed by one cow, which is not additionally milked. Therefore, it represents a compromise between the increasing demands for more animal welfare and the immediate separation of cow and calf after calving. Based on the literature, essential aspe...
Article
Full-text available
In a foster cow system, one or more calves are reared by a foster cow. With regard to the growing rejection towards the early separation of cow and calf after calving, such alternative rearing methods with prolonged cow-calf contact are coming more into focus. Nevertheless, there is a lack of recent studies investigating the effects of suckling mul...
Article
Full-text available
Citation: Köllmann, K.; Wente, N.; Zhang, Y.; Krömker, V. Investigations on Transfer of Pathogens between Foster Cows and Calves during the Suckling Period To date, there have been few studies on the health effects of foster cow systems, including the transmission of mastitis-associated pathogens during suckling. The present study aimed to compare...
Article
Full-text available
To date, there have been few studies on the health effects of foster cow systems, including the transmission of mastitis-associated pathogens during suckling. The present study aimed to compare the pathogens detected in the mammary glands of the foster cow with those in the oral cavities of the associated foster calves and to evaluate the resulting...
Article
Full-text available
In this species differentiation study of Corynebacterium spp. (C. spp.), quarter foremilk samples from 48 farms were included. These were obtained from both clinically healthy cows and those with clinical mastitis. First, all samples were examined cyto-microbiologically and all catalase-positive rods were differentiated using the direct transfer me...
Article
Full-text available
In this species differentiation study of Corynebacterium spp. (C. spp.), quarter foremilk samples from 48 farms were included. These were obtained from both clinically healthy cows and those with clinical mastitis. First, all samples were examined cyto-microbiologically and all catalase-positive rods were differentiated using the direct transfer me...
Article
Full-text available
Intramammary infections before calving and in early lactation have a negative impact on the development of the mammary gland, udder health, the risk of clinical mastitis in early lactation, the risk of premature culling and future milk production in dairy heifers. The aim of this study was to reveal whether and how the somatic cell count of the fir...
Article
Full-text available
To reduce ineffective antimicrobial usage in the treatment of non-severe clinical mastitis (CM) in cows with long-lasting udder diseases, non-antibiotic therapy with a non-steroidal anti-inflammatory drug (NSAID) was conducted and evaluated in a non-blinded, positively controlled, non-inferiority trial. Therefore, three-time systemic ketoprofen tre...
Article
Full-text available
To reduce ineffective antimicrobial usage in the treatment of non-severe clinical mastitis (CM) in cows with long-lasting udder diseases, non-antibiotic therapy with a non-steroidal anti-inflammatory drug (NSAID) was conducted and evaluated in a non-blinded, positively controlled, non-inferiority trial. Therefore, three-time systemic ketoprofen tre...
Article
Full-text available
Bovine mastitis is one of the most important diseases in the dairy industry and has detrimental impact on the economy and welfare of the animals. Further, treatment failure results in increased antibiotic use in the dairy industry, as some of these mastitis cases for unknown reasons are not resolved despite standard antibiotic treatment. Chronic bi...
Article
Full-text available
The aim of this study was to define the time-related period of intramammary infections and its relation to risk factors for intramammary infections and clinical mastitis at cow and quarter levels. In total, 269 German Holstein Frisian dairy cows on three farms in Northern and Eastern Germany were included in this study. Quarter milk samples were co...
Article
Full-text available
Danish veterinarians' treatment approach and use of antibiotics for clinical mastitis were investigated through a web-based questionnaire. The objective of the study was to describe and evaluate how the clinical mastitis treatment practice in Danish dairy herds corresponds to evidence from the literature and legislative requirements, in order to su...
Article
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The objective of this study was to investigate the occurrence of bacteremia in dairy cows with severe mastitis. Milk samples were collected from affected udder quarters, and corresponding blood samples were collected from dairy cows with severe mastitis at the time of diagnosis before any therapeutic measures were undertaken. The cultural detection...
Article
In order to maintain and improve herd udder health a professionally sound, structured approach is required. For that, veterinary advice and support plays a key role. Such consultation includes selection of preventive measures specific to farm and situation, advice on targeted diagnostics and recommendations on effective, antibiotic-saving mastitis...
Article
Full-text available
Streptococcus dysgalactiae is among the most important pathogens causing bovine mastitis. Unfortunately, there is presently a lack of clear knowledge about the mode of transmission—contagious or environmental—of this pathogen. To obtain more information on this, knowledge of the genetic diversity of the isolated microorganisms at the farm level can...
Article
Mastitis-causing pathogens are shed from infected mammary gland quarters and thus contribute to an increased risk of new intramammary infections. The objective of the current study was to investigate the shedding characteristics of various mastitis-causing pathogens and associated animal-specific (somatic cell score and parity) and environmental (h...
Article
Full-text available
The control of clinical mastitis on dairy farms is an essential part of animal health management. Knowledge of the causative microorganisms, the cure rates achievable in the field and essential associated factors are crucial for proper control. The objectives of the present study were to characterize clinical mastitis cases in Germany and to analyz...
Article
Full-text available
Die zytomikrobiologische Untersuchung von Viertelgemelksproben von Milchkühen ist eine in Deutschland weitverbreitete und bewährte Methode, um klinische und subklinische Mastitiden hinsichtlich des verursachenden Mastitiserregers und der somatischen Zellzahl zu analysieren. Zudem ist die Mastitisdiagnostik eine unverzichtbare Säule eines guten Eute...
Article
Full-text available
Intramammary infections (IMI) with Staphylococcus aureus are a common cause of bovine mastitis and can result in both clinical (CM) or subclinical mastitis (SCM). Although bacterial isolates of S. aureus differ in their virulence potential it is largely unclear which bacterial virulence factors are responsible for increased clinical severity. We pe...
Article
Background Aim of the present study was to investigate the implementation of a targeted therapy (tLCT) concept under real-life circumstances, taking both pathogen-related and animal-related factors into account. The reduction of antibiotics without negative effects on cure rates was evaluated as well as the compliance by the farmers. Methods After...
Article
Full-text available
In order to reduce antimicrobial treatment and prevent environmental mastitis, the aim of the present study was to investigate associations between herd level factors and microbial load on teat ends with environmental mastitis pathogens. Quarterly farm visits of 31 dairy farms over a one-year period were used for statistical analysis. During each f...
Article
Corynebacteria are widespread and can be detected in clinical and subclinical mastitis as well as in the milk of udder healthy cows. In detail microbiological characteristics, diagnostic methods and mastitis prevalence are illustrated. The pathogenicity of this bacterial group cannot be clearly classified based on the available knowledge. Corynebac...
Article
The incidence of milk leakage (ML) after dry-off (DO) and related risk factors was studied in 1,175 dairy cows from 41 commercial herds in 8 European countries: Belgium, Czech Republic, Denmark, France, Germany, Italy, the Netherlands, and Spain. Milk leakage was assessed twice for 30 s each during 3 visits at 20 to 24 h, 30 to 34 h, and 48 to 52 h...
Article
The udder health situation of dairy farms in a country influences the average cell count of the milk delivered and thus the average cell count of the country. As this variable is used to describe the milk quality of a country, it is important for the reputation of the industry beyond the individual herd. As part of a project funded by the State Dai...
Article
Full-text available
To reduce the negative effects of mastitis in dairy heifers in early lactation on the future milking performance, the aim of this study was to define the time-related period of intramammary infections and to relate this to risk factors at heifer and quarter level for intramammary infections and subclinical mastitis. In total, 279 German Holstein Fr...
Poster
Full-text available
Bovine mastitis is an inflammation that is related to microorganisms in many ways. Microorganisms colonize the teat skin and teat canal, they penetrate the mammary gland, adapt to the glandular epithelium, form biofilms there, interact with the microbiome, dissolve and stimulate inflammatory processes and destroy the glandular tissue and the blood-...
Article
Full-text available
The aim of this study was to examine the opinions of farmers on a consulting project, which was established for organic dairy farms in Northern Germany involving different animal health experts who participated in the meetings. Furthermore, the properties of measures that are of decisive importance for implementation on the farms were identified to...
Article
Full-text available
The aim of the current study was to investigate the effects of the prepartum external treatment of teats with a combination of four lactic acid bacteria strains viz. Lactobacillus (Lb.) rhamnosus ATCC 7469, Lactococcus lactis subsp. lactis ATCC 11454, Lb. paracasei 78/37 (DSM 26911), and Lb. plantarum 118/37 (DSM 26912) on the postcalving udder hea...
Article
Recurrent clinical mastitis contributes to around half of all infections having an economic impact in the dairy industry. It leads to milk yield reduction, increased risk of mortality, and culling, and may be caused by new infections or a persistent infection after previous treatment. Disease management is dependent on the infecting species, necess...
Article
Full-text available
The aim of this study was to examine the opinions of farmers on a consulting project, which was established for organic dairy farms in Northern Germany involving different animal health experts who participated in the meetings. Furthermore, the properties of measures that are of decisive importance for implementation on the farms were identified to...
Article
Full-text available
The aim of this research was to compare two sampling methods quantifying microbial load on teat ends, especially mastitis pathogens originating from the cows' surroundings. Methods were compared using a split udder design, including 132 teat pairs in the study. For the first method, the wet/dry swab technique, a moistened swab was rotated 360° arou...
Article
Full-text available
The antimicrobial activity of a phage mixture and a lactic acid bacterium against Staphylococcus aureus isolates from bovine origin was investigated in vitro with regard to possible applications in the therapy of udder inflammation (mastitis) caused by bacterial infections. The S. aureus isolates used for inoculation derived from quarter foremilk s...
Article
Non-S. aureus staphylococci (NAS) are the most frequently isolated pathogens from bovine milk and can cause intramammary infections (IMI). They can also be found in teat canals, on bovine skin and in cows' environment, which may lead to unnoticed contamination of milk samples. The aim of this study was to investigate the role of NAS species as mast...
Article
Full-text available
The lytic efficacy of bacteriophages against Staphylococcus aureus isolates from bovine milk was investigated in vitro, regarding possible applications in the therapy of udder inflammation caused by bacterial infections (mastitis). The host range of sequenced, lytic bacteriophages was determined against a collection of 92 Staphylococcus (S.) aureus...
Article
Staphylococcus aureus is one of the most common pathogens associated with bovine mastitis in Germany and Denmark. Successful therapy is strongly linked to the susceptibility of the pathogen to the administered antimicrobial. An increase in resistant pathogens in human and veterinary medicine has become a concern worldwide and hampers therapy due to...
Article
Full-text available
Staphylococcus aureus is recognized worldwide as one of the main contagious mastitis agents in cattle and can express a set of antimicrobial resistance genes and virulence-associated genes that explain the wide range of outcomes of intramammary infections. Staphylococcus aureus strains are heterogeneous: their different resistance and virulence pat...
Article
Full-text available
The present research study investigated the susceptibility of common mastitis pathogens—obtained from clinical mastitis cases on 58 Northern German dairy farms—to routinely used antimicrobials. The broth microdilution method was used for detecting the Minimal Inhibitory Concentration (MIC) of Streptococcus agalactiae (n = 51), Streptococcus dysgala...
Article
The microbiological diagnosis of mastitis is an essential part of mastitis control. Different microorganisms have different habitats and require different methods of control to reduce new infections and shorten existing infections. The increase in microbiological methods has considerably increased the diagnostic possibilities in recent years. Rapid...
Article
Mastitis ist die häufigste Krankheit bei Milchkühen und beeinflusst das Wohlbefinden der Tiere, die Milchqualität und die Rentabilität der Milchviehhaltung erheblich. Seit 100 Jahren existiert die Zeitschrift „Der praktische Tierarzt“ und seit Beginn dieser Zeit wird der aktuelle Stand des Wissens der Mastitisbekämpfung dargestellt. Das Jubiläum de...
Article
Bovine clinical mastitis quarter foremilk samples were collected from 15 German dairy farms for the isolation of Streptococcus uberis strains. Samples were also collected from the 8 spots where Streptococcus uberis was most expected in the dairy environment to investigate the transmission behavior of Streptococcus uberis within the farm. The select...
Article
Full-text available
A non-blinded, positively controlled trial was conducted to evaluate the efficacy of an alternative, non-antibiotic therapy with Pyrogenium® to reduce ineffective antibiotic usage in the treatment of non-severe clinical mastitis (CM) in cows with longer lasting udder diseases. The solely treatment with Pyrogenium® (6 times, at a 12 hourly interval...
Article
Full-text available
The aim of this prevalence study was to describe the udder health situation at herd level of organic dairy herds in Northern Germany. Data from 21 voluntarily participating organic dairy herds (12-290 cows) were collected between 2011 and 2016, including somatic cell counts (SCC) from the dairy herd improvement test (DHI-test). Based on key figures...
Article
Full-text available
The objective of this study was to gain information on udder health management and the use of antimicrobials in mastitis in dairy cows. The role of veterinarians in udder health management on dairy farms in Germany was a further focal point of this study. A total of 499 completed survey forms were returned by participating farms from nine federal s...
Article
Full-text available
Mastitis poses a considerable threat to productivity and to animal welfare on modern dairy farms. However, the common way of antibiotic treatment does not always lead to a cure. Unsuccessful cures can, among other reasons, occur due to biofilm formation of the causative agent. This has attracted interest from researchers to introduce promising alte...
Article
Full-text available
The purpose of this investigation was to compare herd-level udder health regarding the extend of access to pasture and other management factors associated with pasturing and to determine pasture-associated risk factors. Data were provided by monthly dairy herd improvement test and collected over a period of 3 years and 4 months from 60 commercial d...
Article
Full-text available
The purpose of this investigation was to compare herd-level udder health regarding the extend of access to pasture and other management factors associated with pasturing and to determine pasture-associated risk factors. Data were provided by monthly dairy herd improvement test and collected over a period of 3 years and 4 months from 60 commercial d...
Article
Objective: To evaluate the relative efficacy of a novel, commercially available disinfecting agent containing ≥ 15 to < 20 % glutaraldehyde in a hydro-colloid matrix ("EIMÜ Klauen Sprint®"; Eimermacher, Nordwalde, Germany, Biozid-Desinfektionsmittel, BAuA Nr. N-57213) as a walkthrough footbath in order to treat digital dermatitis of dairy cattle....
Article
Full-text available
Antibiotic use in dairy farming is a highly discussed issue in society. As a result, the European commission issued guidelines for the prudent use of antimicrobial agents in veterinary medicine in 2015 (EU 2015/C 299/04). Several studies could show effects of selective treatment of clinical mastitis. The present study assesses antibiotic reduction...
Article
The objective of this study was to investigate the association between teat skin colonization and intramammary infection (IMI) with Staphylococcus aureus or Streptococcus agalactiae at the quarter level in herds with automatic milking systems. Milk and teat skin samples from 1,142 quarters were collected from 300 cows with somatic cell count >200,0...
Article
Bovine mastitis caused by Mycoplasma and in particular by Mycoplasma (M.) bovis is a serious animal-health problem for (bigger) dairy herds. It is a highly contagious disease with low infectious doses and with high amounts of shedding. This can lead to a rapid dissemination of the infections in a herd followed by milk yield decline. After appearanc...