The incidence of antimicrobial-resistant Salmonella spp on freshly processed poultry from US Midwestern processing plants

AIMS: To determine the incidence of antimicrobial-resistant Salmonella spp. on processed poultry (turkey) at Midwestern poultry plants. METHODS AND RESULTS: Two participating plants were visited at monthly intervals for a period of 1 year. Surface swabs were obtained from carcasses at two selected points on the production line, pre- and post-chill. In addition, samples of the chill water from chill tanks were also examined. Isolation and detection of Salmonella spp. from carcass swabs and chill water was carried out using standard enrichment techniques. Immunomagnetic separation was used to enhance the recovery of the pathogen. Salmonella isolates recovered were identified, serotyped and their antimicrobial resistance profiles determined using the National Antimicrobial Resistance Monitoring System. Results from the study indicated that the overall incidence of Salmonella was approx. 16.7%, with a greater incidence of the pathogen observed on pre-chill than post-chill carcasses. Salmonella isolates recovered displayed resistance to an average of four different antimicrobials. Approximately 15 different serotypes of Salmonella spp. were recovered, with Salmonella serotype Agona, Salmonella serotype Hadar, Salmonella serotype Heidelberg and Salmonella serotype Senftenberg being the most common. CONCLUSIONS: The incidence of Salmonella spp. was relatively low and isolates recovered showed significant degrees of antimicrobial resistance. Factors such as the processing plant examined, the season and farms that were presenting animals for processing influenced the incidence of the pathogen. SIGNIFICANCE AND IMPACT OF THE STUDY: Differences were observed in the serotypes of Salmonella recovered and the types of antimicrobial resistance found at the two plants. The study suggests that the use of antimicrobials at the farm level influences the creation of an environment that promotes the selection of antimicrobial-resistant Salmonella spp. The incidence, isolation and detection of Salmonella spp. on processed poultry are discussed.