| Summary: | Avian pathogenic <i>Escherichia coli</i> (APEC) causes colibacillosis in poultry, a leading cause of poultry mortality worldwide. It is crucial to control APEC in broiler breeders as it is vertically transferred to progeny via eggs. However, there is only limited knowledge on the current APEC population in breeders. This study characterized 28 APEC strains isolated from broiler breeders with colibacillosis. The genotypic-virulence characteristics as well as antimicrobial and heavy-metal resistance patterns of the isolates were determined. Results showed that O88 is the most prevalent serogroup and B2 is the predominant phylogenetic group. Among virulence genes, genes for iron acquisition (<i>iroN</i> and <i>iutA</i>), protectins (<i>iss</i> and <i>ompT</i>), and toxin production (<i>hlyF</i>) exhibited the highest prevalence. Further, 93% of the isolates carried at least one antimicrobial resistance gene with highest prevalence for tetracycline gene <i>tetA</i>. Among the isolates, 10.71% exhibited multidrug resistance. All isolates carried at least one heavy-metal resistance gene with the highest prevalence for arsenic gene <i>arsC</i> and the highest resistance towards silver. Our findings provide insight into the characteristics of current APEC populations in broiler breeders in Mississippi. This will help future research on the pathogenesis of APEC and the development of effective prevention and control strategies against APEC in broiler breeders.
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