Purpose: To determine the presence and AMR patterns of Salmonella isolated from goat and lamb carcasses in the United States and Bahamas.
Methods: Carcass surface swabs were collected from 122 goats and 173 lambs at abattoirs in California, New Mexico, Texas and Bahamas over two years. Samples were analyzed using Genedisc® for Salmonella detection, with potential positive samples presumptively confirmed by traditional culturing methods and latex agglutination. Isolates were frozen in duplicate with 20% glycerol. Frozen isolates were recovered and subjected to antimicrobial testing using the National Antimicrobial Resistance Monitoring System (NARMS) protocol. AMR was determined using 96-well gram negative plates with predetermined concentrations of a panel of 15 antibiotics, and resistance determined using the Sensititre™ automated antimicrobial susceptibility system.
Results: Salmonella was detected on 3.1% of carcass surfaces at preevisceration, 4.8% at post-evisceration, and 2.0% at postintervention (after application of organic acid). Nine Salmonella isolates collected at postevisceration, and 12 postintervention isolates were successfully recovered and subjected to AMR testing. According to the predetermined MIC breakpoints tetracycline resistance was found in 10% (n=2) of isolates. Resistance to azithromycin was found in 5% (n=1) of isolates. Intermediate resistance was determined for amoxicillin, ampicillin in 10% (n=2) and chloramphenicol in 5% (n=1) of isolates. None of the isolates expressed multi-drug resistance (MDR).
Significance: This information contributes to the understanding of goat and lamb safety in the retail case. The absence of MDR Salmonella from small ruminants is notable, and is preliminary evidence that sheep and goats may not be contributing to MDR development in the food supply system.