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Salmonella spp. carriage in fecal of bovine origin in Tizi Ouzou Algeria 2020
Abstract
The objective of this study was to evaluate the importance of the reservoir of Salmonella spp. in dairy cattle through the study of asymptomatic carriage in feces in some municipalities of the Wilaya of Tizi Ouzou. 548 fecal samples from 65 farms were carried out, and the ISO 6579 method was used for the analysis of the samples. The results showed that 13.48% of the farms and 2.18% of the samples were positive for the search of Salmonella spp. Most of the strains (75%) were resistant to a maximum of two antibiotics and 25% of the strains were multidrug resistant. No relationship between practices observed in the field and the excretion of Salmonella spp. could be demonstrated.
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Salmonella infections in dairy cattle continue to be a major worldwide problem. Substantial economic
losses were manifested through mortality and poor growth of infected animals as well as the hazard of transmission
to humans either through food chain or direct animal contact. Our objective was the isolation and identification of
Salmonella spp. shed in feces of dairy cattle and their attendants, together with the determination of their serotypes
and antimicrobial susceptibility patterns. Fecal samples were cultured on non selective pre-enrichment broths, and
selective enrichment broths and agar media. Serotyping of Salmonella spp. isolates was performed by slide
agglutination tests and then screening for their antibiotic susceptibility. Seven Salmonella spp. (1.56%) were isolated
from the 450 examined dairy cattle, while no Salmonella spp. were isolated from any of the examined attendants.
Salmonella isolates were classified as serogroups B, C1, D1 and E1, with C1 as the most commonly observed
serogroup (57.1%). Five different Salmonella serotypes were identified (Typhimurium, Anatum, Concord,
Montevideo and Enteritidis). The 7 isolated Salmonella spp. showed no resistance to all tested antimicrobial agents
except for trimethoprim-sulphamethoxazole and gentamycin. Application of optimal hygienic conditions and
management strategies minimize the occurrence and spread of the Salmonella infections on dairy farms, as no
Salmonella spp. were isolated from farm C, which had the proper hygienic conditions and management practices.
The consumption of meat from cull dairy cows and of raw milk has been associated with foodborne salmonellosis. This survey was conducted to establish the prevalence of Salmonella in cull dairy cow fecal samples and bulk tank milk and to determine the proportion of Salmonella-positive dairy farms (n = 30) in east Tennessee. Food and Drug Administration bacteriological analytical protocols were generally used for Salmonella isolation. Primary enrichment was performed with lactose broth, and secondary enrichment was conducted with tetrathionate broth. Eosin methylene blue, hektoen enteric, xylose lysine desoxycholate, bismuth sulfite, and brilliant green (BG) were used as isolation agars. BG agars supplemented with individual antibiotics and/or sulfur compounds were also evaluated. Six of 268 (2.24%) bulk tank milk samples and 9 of 415 (2.17%) fecal samples from 7 of 30 (25.3%) dairy farms were Salmonella-positive. Most isolates (11 of 15) were obtained between September and December. Salmonella isolates were further characterized using polyvalent somatic O Salmonella antiserum, o-nitrophenyl-beta-D-galactopyranoside (ONPG), and Analytical Profile Index (API) 20E strips for Enterobacteriaceae. Serological evaluation of presumptive positive Salmonella isolates resulted in substantial numbers of false positives (41.2%). ONPG and API 20E tests enabled further biochemical distinction of the majority of Salmonella spp. from Salmonella Arizonae and closely related members of Enterobacteriaceae like Citrobacter youngae. Pulsed-field gel electrophoresis of SpeI-digested Salmonella DNA was used to subtype isolates. The isolates grouped into four clusters. The baseline information generated in this survey is being used to develop preharvest pathogen reduction programs on selected farms.
Salmonella enterica serovar Typhimurium was isolated from a pig, a calf, and a child on a farm in the Netherlands. The isolates were indistinguishable by phenotyping and genotyping methods, which suggests nonfoodborne animal-to-animal and animal-to-human transmission. Persons in close contact with farm animals should be aware of this risk.
To determine the prevalence, serotype and antibiotic resistance profile of Salmonella isolates in cattle and on carcasses at a commercial Irish abattoir.
Faecal, rumen and carcass samples were collected from a beef abattoir over a 12-month period and examined for the presence of Salmonella spp. Isolates were serotyped, phage typed (when serotype was found to be S. Typhimurium) and tested for susceptibility to a panel of antibiotics. Salmonella was isolated from 2% of faecal, 2% of rumen and 7.6% of carcass samples. Salmonella was most frequently isolated from samples taken during the period August to October. S. Dublin was isolated from 72% of positive samples. S. Agona and S. Typhimurium definitive type (DT)104 were each isolated from 14% of positive samples. All S. Typhimurium DT104 isolates were resistant to ampicillin, chloramphenicol, streptomycin, sulphafurazole and tetracycline (ACSSuT). On occasion, from a single animal, the same serotype was isolated from more than one sample (i.e. faeces and rumen; faeces and carcass; rumen and carcass; faeces, rumen and carcass).
Salmonella is present in cattle at slaughter and on beef carcasses at an Irish abattoir, with a higher frequency of occurrence during the period August to October. Most isolates from the study are not commonly associated with human clinical infection, with the exception of S. Typhimurium DT104 (R-type ACSSuT).
This study provides epidemiological data that is necessary for the understanding of beef as a source of human Salmonella infection.
Salmonella is one of the most serious foodborne pathogenic bacteria in the United States, causing an estimated 1.3 million human illnesses each year. Dairy cows can be reservoirs of foodborne pathogenic bacteria, including Salmonella spp.; it is estimated that from 27 to 31% of dairy herds across the United States are colonized by Salmonella. The present study was designed to examine the occurrence of Salmonella spp. on dairies and to examine the serotypic diversity of Salmonella isolates on sampled dairies from across the United States. Fecal samples (n = 60 per dairy) were collected from 4 dairies in each of 4 states for a total of 960 fecal samples representing a total population of 13,200 dairy cattle. In the present study, 93 of 960 samples (9.96%) collected were culture-positive for Salmonella enterica. At least one Salmonella fecal-shedding cow was found in 9 of the 16 herds (56%) and the within-herd prevalence varied in our study from 0% in 7 herds to a maximum of 37% in 2 herds, with a mean prevalence among Salmonella-positive herds of 17%. Seventeen different serotypes were isolated, representing 7 different Salmonella serogroups. There were 2 or more different serogroups and serotypes present on 7 of the 9 Salmonella-positive farms. Serotypes Montevideo and Muenster were the most frequent and widespread. From our data, it appears that subclinical colonization with Salmonella enterica is relatively common on dairy farms and is represented by diverse serotypes on US dairy farms.
Between October 1999 and February 2001 the salmonella status of 449 dairy farms in England and Wales was determined by environmental sampling on up to four occasions. Data were collected through interview-based questionnaires, and multivariable analyses were used to identify risk factors associated with the farms either being Salmonella positive (prevalence data) or becoming Salmonella positive (incidence data). Region, herd size, month of visit and the lack of a clean visitor parking area were significantly associated with the prevalence of Salmonella species, and there was a significant trend towards an increased risk in late summer and autumn. The introduction of six- to 24-month-old cattle into a herd was associated with a reduced prevalence, but the introduction of adult cattle only, or calves with other cattle, was associated with an increased (but not significant) risk of farms being Salmonella positive. Month of visit, the lack of a clean visitor parking area, the use of part-time workers and not feeding calves whole milk, but not region or herd size, were associated with an increased incidence of salmonella.
Nontyphoid salmonellosis has been said to be a zoonosis; hence, antibiotic resistance in the salmonella serotypes is thought
to be derived directly from resistance in the animal reservoir. This thesis seems incorrect for the following reasons: (1) Typhoid and paratyphoidal salmonellae are clearly exceptions to the rule since they are restricted to human hosts. (2) Salmonella isolates involved in food-borne outbreaks of disease have not been notable in terms of their antibiotic resistance.
(3) In contrast, outbreaks of nosocomial disease, transmitted from person to person and persisting for long periods, have produced
and disseminated multiply resistant salmonellae, such as Salmonella wien (another serotype without an animal reservoir) in western Europe. (4) In western Europe and the United States, there are often large differences between the resistance of isolates from animals
and that of isolates from humans. (5) In most reported outbreaks of disease caused by antibiotic-resistant Salmonella in humans or animals, the administration of therapeutic concentrations of antibiotics has been implicated. (6) The role of
low-concentration, growth-promoting antibiotic feed supplements has been much discussed but never has been delineated or proven.
In fact, these supplements probably are totally irrelevant to the development of antibiotic resistance in Salmonella. With regard to Salmonella, there is an exception to every rule; in this case the exception is Salmonella dublin, which in western Europe is a highly antibiotic-resistant serotype in cattle and appears in humans with a similar - and unusual-
pattern of resistance.
To estimate prevalence of Salmonella spp in Ohio dairy farms and to identify potential risk factors for fecal shedding of salmonellae.
Cross-sectional study.
105 Ohio dairy farms.
Individual fecal samples from all mature cows in study herds were tested for Salmonella spp by use of standard bacteriologic culture procedures. Herds were identified as infected if at least 1 cow was shedding Salmonella spp. Information regarding herd characteristics, management practices, and health history were collected. Potential risk factors for herd-level Salmonella infection were identified.
In 31% of the study herds (95% confidence interval, 22 to 40%), at least 1 cow was shedding Salmonella spp. Six percent of 7,776 fecal samples contained Salmonella organisms; prevalence within infected herds ranged from < 1 to 97%. Herd size, use of free stalls for lactating and nonlactating cows, and use of straw bedding in nonlactating cows were significantly associated with fecal shedding of Salmonella spp, as determined by use of univariate analysis. By use of multivariate analysis, large herds were more likely to be infected than smaller herds; however, no other factors were associated with Salmonella infection after adjustment for herd size.
Subclinical shedding of Salmonella spp is common in Ohio dairy herds, although we could not identify specific interventions that may influence the prevalence of Salmonella spp on dairy farms. It appears that large herd size and intensive management may provide an environment conducive to Salmonella shedding and chronic dairy herd infection.
To examine healthy slaughter-age cattle and sheep on-farm for the excretion of Salmonella serovars in faeces and to identify possible risk factors using a questionnaire.
The study involved 215 herds and flocks in the four eastern states of Australia, 56 with prior history of salmonellosis. Production systems examined included pasture beef cattle, feedlot beef cattle, dairy cattle, prime lambs and mutton sheep and animals were all at slaughter age. From each herd or flock, 25 animals were sampled and the samples pooled for Salmonella culture. All Salmonella isolated were serotyped and any Salmonella Typhimurium isolates were phage typed. Questionnaires on each production system, prepared in Epi Info 6.04, were designed to identify risk factors associated with Salmonella spp excretion, with separate questionnaires designed for each production system.
Salmonellae were identified in all production systems and were more commonly isolated from dairies and beef feedlots than other systems. Statistical analysis revealed that dairy cattle were significantly more likely to shed Salmonella in faeces than pasture beef cattle, mutton sheep and prime lambs (P<0.05). A wide diversity of Salmonella serovars, all of which have been isolated from humans in Australia, was identified in both cattle and sheep. Analysis of the questionnaires showed access to new arrivals was a significant risk factor for Salmonella excretion on dairy properties. For beef feedlots, the presence of large numbers of flies in the feedlot pens or around stored manure were significant risk factors for Salmonella excretion.
Dairy cattle pose the highest risk of all the slaughter-age animals tested. Some of the identified risk factors can be overcome by improved management practices, especially in relation to hygiene.