Genetic diversity and antimicrobial resistance profiles ofin the broiler supply chain in Harare, Zimbabwe: tracking transmission from farm to table.

Abstract

is a significant zoonotic pathogen, posing a serious public health threat through its presence in the food supply chain, particularly in poultry production facilities. This study aimed to investigate the genetic diversity, antimicrobial resistance (AMR) profiles and phylogenetic relationships ofserovars isolated from various stages of the broiler supply chain in Harare, Zimbabwe. Whole-genome sequencing was employed to analyse 28isolates from broiler farms, slaughter facilities and retail markets. The overall prevalence ofwas 5.1% out of 552 samples tested. Contamination rates were higher at slaughter facilities, where 11% of 100 samples tested positive and at retail markets, where 20% of 20 samples were contaminated. In contrast, farms had a significantly lower prevalence, with only 3.0% of 432 samples showingpresence. Eight serovars were identified, withsubsp.serovar Typhimurium being the most prevalent at 27.6%. Notably, 34.5% of the isolates harboured resistance genes, including,and, and exhibited mutations in theandregions. An extended-spectrum beta-lactamase-producingsubsp.serovar Kentucky ST198 strain was isolated from retail chicken cuts. All isolates carried virulence genes such as,and, withpresent in 47.4% of the isolates. Approximately 31% of the isolates co-harboured antimicrobial, stress tolerance and virulence genes. Genomic analysis identified distinct sequence types while also revealing identical core SNPs in genomes across various stages of the supply chain. This study highlights the transmission ofand AMR in the broiler supply chain, emphasizing the urgent need for improved surveillance and intervention strategies to reduce public health risks from contaminated poultry products.