Prevalence and Antimicrobial Resistance of Salmonella and Campylobacter in a Poultry Facility that Processes Antibiotic-free Broilers Using Organic and Conventional Methods

Matthew Bailey, Purdue University


Salmonella and Campylobacter are important pathogens in terms of food safety, and are leading causes of foodborne illness worldwide. Management practices aimed at controlling these pathogens during production and processing of poultry are important for safeguarding public health. The use of organic and antibiotic-free practices has become more frequent in the production of chicken, however the impact of these methods on Salmonella and Campylobacter in terms of prevalence and antimicrobial resistance is still uncertain. It may be the case that outdoor-access requirements for organic birds increases the likelihood of a flock becoming contaminated by outside sources such as wild animals and birds. In addition, removal of selective pressure by eliminating antibiotic use on the farm is thought to be an effective measure against rising prevalence of AMR pathogens. In this experiment, these hypotheses were tested by sampling a processing plant that produces “antibiotic-free” chicken using organic and conventional processing methods. Samples were collected on 16 days (8 each for organic and conventional birds) over a 1-year period. Samples included fecal samples from incoming birds, carcass rinses at important processing steps, and environmental samples. Differences in prevalence of Salmonella and Campylobacter between methods (organic and conventional) were assessed and isolates collected in this study were tested for AMR using methods published by NARMS. Organic methods were associated with higher prevalence of Salmonella but lower prevalence of Campylobacter during early processing steps. No major differences in prevalence between methods were observed post-chill. Prevalence of AMR Salmonella was lower in these antibiotic-free birds than was reported by NARMS in chickens at slaughter. However, AMR prevalence was higher in Campylobacter than was observed by NARMS. These results indicate that organic methods may result in increased initial prevalence of Salmonella, but decreased initial prevalence of Campylobacter, although higher prevalence associated with either organic or conventional methods is managed by proper processing interventions. Additionally, although these results support the hypothesis that elimination of antibiotics reduces the prevalence of AMR Salmonella, this does not appear to be true for Campylobacter for most antimicrobials tested.




Singh, Purdue University.

Subject Area

Food Science

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