Frequency, serotype distribution, and antimicrobial susceptibility patterns of Salmonella in small poultry flocks in California

Abstract

Backyard poultry operations are increasingly popular and commonplace in both rural and suburban locations. Although Salmonella surveillance programs are well established for large commercial poultry systems, information on smaller operations is lacking. We identified the occurrence and serotype distribution of Salmonella spp. recovered from backyard flock cases submitted to the California Animal Health and Food Safety Laboratory System (Davis, CA) in 2012–2015, and evaluated minimum inhibitory concentration for 12 antimicrobials as well as the lesions associated with Salmonella spp. in these cases. From records of 2,347 backyard flock cases with 2,627 samples, 44 samples (1.7%) were positive for Salmonella spp. DNA by PCR, and 41 (1.6%) of these samples yielded a Salmonella isolate by culture for further characterization. Seventeen different serotypes, including 3 isolates identified to the serogroup level, were identified from these isolates. Antimicrobial resistance was infrequent; however, 2 multidrug–resistant isolates were identified. Enteric or systemic lesions associated with Salmonella recovery were uncommon, with 77.3% of cases having no disease attributable to Salmonella. Recovered serotypes overlap with those seen in commercial poultry as well as in foodborne outbreaks reported by the Centers for Disease Control and Prevention in humans. Zoonotic risks via contact and food product contamination make monitoring of backyard flocks for Salmonella a critical part of flock surveillance programs, and we propose a potential sampling scheme.