Antimicrobial resistance in Salmonella serotypes isolated from slaughter animals in Kenya

Objectives: To isolate Salmonella from food animals and characterise the antimicrobial resistance of the isolates. Design: A random sampling of slaughter animals was carried out. Setting: Department of Public Health, Pharmacology and Toxicology, University of Nairobi, Kenya and Institute for Animal Breeding, Neustadt-Mariensee, Germany. Subjects: Two hundred and eighty five samples, including faecal samples and carcass, cloacal and pharyngeal swab samples were analysed. Results: Sixteen (5.6%) of 285 samples were positive for Salmonella. The prevalence of Salmonella on pig carcasses (19%) was higher than in faeces (8.6%). Three Salmonella enterica sub-species enterica serovars, namely Saintpaul (S. Saintpaul), Braenderup (S. Braenderup), and Heidelberg (S. Heidelberg), were identified, with S. Saintpaul being the predominant serovar. Antimicrobial resistance was found in 35.7% of all the isolates. The S. Heidelberg isolates were susceptible to all the antimicrobial agents tested. Multidrug resistance was found in 7.1% of the resistant Salmonella isolates. Plasmids were only detected in S. Heidelberg. Ampicillin resistance was based on expression of a blaTEM gene, while chloramphenicol, streptomycin, and tetracycline resistances were encoded by the genes catAl, strA, and tet(A), respectively. Conclusion: Pigs may serve as reservoirs of antimicrobial resistant Salmonella and slaughterhouse cross-contamination of pork may be a food safety risk. We recommended that slaughterhouse hygiene be improved to minimise contamination of pig carcasses.