Multiplex PCR analysis of virulence genes and their influence on antibiotic resistance in Enterococcus spp. isolated from broiler chicken

spp. are opportunistic pathogens that cause lameness in broiler chickens, resulting in serious economic losses worldwide. Virulence of spp. is associated with several putative virulence genes including , , , , , , , and . In this study, multiplex polymerase chain reaction (PCR) for the simultaneous detection of these virulence genes in spp. was developed, and detection limits for , , and were 64.0 pg/μL, 320.0 pg/μL, and 1.6 ng/μL DNA, respectively. Among 80 isolates tested, and were detected in all 26 samples, and only was observed in . Additionally, the presence of virulence genes in 25 isolates were 100% for , 88.0% for , 64.0% for , 44.0% for , 16.0% for , and 4.0% for . No virulence genes were found in isolates. A total of 49 isolates were resistant to tigecycline and to at least 2 different classes of antibiotics. The most prevalent resistance was to ciprofloxacin (73.5%), quinupristin/dalfopristin (55.1%), and tetracycline (49.0%). No strains were resistant to vancomycin or linezolid. This is the first multiplex PCR assay to simultaneously detect eight virulence genes in spp., and the method provides diagnostic value for accurate, rapid, and convenient detection of virulence genes. Additionally, we report the prevalence of virulence genes and antimicrobial resistance in isolates from commercial broiler chickens suffering lameness.