Occurrence and Characterization of<i> Salmonella</i> Isolated from Large-Scale Breeder Farms in Shandong Province, China

Abstract

This study aimed to investigate the prevalence and antimicrobial resistance of <i>Salmonella</i> spp. isolated from large-scale breeder farms in Shandong Province, China. A total of 63 <i>Salmonella</i> isolates (63/409, 15.4%) were identified from 409 samples collected from five large-scale breeder farms in Shandong Province. These <i>Salmonella</i> isolates were assayed for serotype, antimicrobial susceptibility, prevalence of class 1 integrons, quinolone resistance genes, and <i>β</i>-lactamase genes and subtyped by multilocus sequence typing (MLST). Among these isolates, <i>S</i>. Enteritidis (100%) was the predominant serovar, and high antimicrobial resistance rates to nalidixic acid (100.0%), streptomycin (100.0%), ampicillin (98.4%), and erythromycin (93.7%) were observed. All of the isolates carried blaTEM. MLST results showed that only one sequence type (ST11) was identified. Our findings indicated that <i>Salmonella</i> was generally prevalent not only on broiler farms but also on breeder farms.