PREVALENCE, DISTRIBUTION AND ANTIMICROBIAL RESISTANCE OF SALMONELLA ISOLATES FROM SLAUGHTERED CATTLE IN DEBRE ZEIT, ETHIOPIA
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2006-06
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Abstract
A cross-sectional study was conducted on slaughtered cattle at a commercial slaughterhouse in Debre Zeit from October 2005 to February 2006 with the objectives of estimating the prevalence, serotype distribution, the antimicrobial resistance of Salmonella isolates from cattle and to investigate the association between some potential sources of Salmonella carcasses contamination. A total of 800 samples consisting of (n =100) swabs each, from, hides, flayer’ hands, eviscerator’s hands, carcasses and holding pens and similar number of samples from caecal and rumen contents and mesenteric lymph nodes, were collected separately. The samples were examined for the presence of Salmonella following standard techniques and procedures recommended by the International Organization for Standardization (ISO).
Out of a total of 800 samples, 87 (10.9%) were Salmonella positive. Thirty-one (31%) of the hides, 19 (19%) of the rumen contents, 12 (12%) of the holding pens, 8 (8%) of the mesenteric lymph nodes, 7 (7%) of the flayer's hands, 6 (6%) of the caecal contents, 2 (2%) of eviscerator's hands and carcasses each, were positive out of 100 samples examined for each of the sample types. No statistically significant association (P > 0.05) could be demonstrated between the bacteriological status of the samples from potential sources of contamination and bacteriological status of the carcasses.
Among the 87 Salmonella isolates 85 were identified as serotypes belonging to Salmonella enterica subsp enterica classified under eight serotypes, while the rest two isolates were grouped under subspecies salame. Salmonella Anatum (63.2%) and S. Newport (20.7%), were the most prevalent. Other serotypes isolated include S. Reading (5.7%), S. Eastbourne (3.4%), S. II 40:b:- (2.3%), S. Bredeney, S. Typhimurium, S. Uganda and S. Urbana, 1.1% each. The two predominant serotypes were isolated from, the hide, rumen contents, caecal contents, personnel hands, mesenteric lymph nodes and holding pens. Salmonella Urbana and S. Eastbourne were the only two isolates recovered from the carcasses.
All of the isolates were tested for susceptibility to a panel of eight antimicrobials. Out of the 87 isolates tested, 36 (41.4%) were resistant. All serotypes, with the exception of S. Bredeney, S.
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Typhimurium and S. Urbana, had at least one serotype resistant to one or more of the antimicrobials tested. Multiple antimicrobial resistance was detected for 11.1% of the isolates. Most frequent resistance was encountered for streptomycin (24.1%), followed by tetracycline (20.7%) and amoxicillin/clavulanic acid (2.3%). The most common resistance pattern was a monodrug resistance pattern to streptomycin representing 47.2% of the resistant isolates.
Results of this study showed that Salmonella are widespread in cattle at slaughter, personnels’ hands and the slaughterhouse environment; however the carcass contamination level was low. The study also indicated the need for further studies to be undertaken to determine risk factors associated with Salmonella in cattle and risk factors associated with antimicrobial resistance so that appropriate measures should be taken to reduce Salmonella infection and contamination in slaughter animals and thereby minimize the potential foodborne Salmonella infection in man.
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Cattle, Salmonella, prevalence, antimicrobial resistance, Ethiopia