Assessment and genomic analysis of Salmonella and Campylobacter from different stages of an integrated no-antibiotics-ever (NAE) broiler complex: a longitudinal study.

ABSTRACT

The objective of this study was to determine prevalence and perform genomic analysis of Salmonella spp. and Campylobacter spp. isolated from different stages of an integrated NAE broiler complex. Environmental samples were screened with 3M-Molecular Detection System (MDS) and MDS positive samples were further processed for confirmation of results and identification. Core genome-based phylogenies were built for both bacteria isolated from this study along with selected NCBI genomes. The odds ratios and 95% confidence limits were compared among stages and sample types (α < 0.05) using multivariable model. Based on MDS results, 4% and 18% of total samples were positive for Salmonella spp. and Campylobacter spp. respectively. The odds of Salmonella detection in hatchery samples were 2.58 times as likely as compared to its detection in production farms' samples (P = 0.151) while the odds of Campylobacter detection in production farms' samples were 32.19 times as likely as its detection in hatchery (P = 0.0015). Similarly, the odds of Campylobacter detection in boot swabs, soil, water, and miscellaneous samples were statistically significant (P < 0.05) as compared with fly paper as reference group. The serovars identified for Salmonella were Typhimurium, Barranquilla, Liverpool, Kentucky, Enteritidis, Luciana, and Rough_Or1,5. For Campylobacter, the species identified were Campylobacter jejuni and Campylobacter coli. Phylogeny results show close genetic relatedness among bacterial strains isolated from different locations within the same stage and between different stages. The results show possibility of multiple entry points of such bacteria entering broiler complex and can potentially contaminate the final raw product in the processing plant. It suggests the need for a comprehensive control strategy with strict biosecurity measures and best management practices to minimize or eliminate such pathogens from the poultry food chain.