Prevalence of blaZ gene and other virulence genes in penicillin-resistantStaphylococcus aureus isolated from bovine mastitis cases in Gansu, China

Abstract

Staphylococcus aureus is a major etiological agent of bovine mastitis worldwide. In this study, 37 strains of S. Aureus resistant to penicillin were isolated from bovine mastitis cases in Gansu Province for investigating blaZ and virulence-related genes, including tst, eta, etb, lukPV, lukED, lukM, hla, hlb, hld, and edin. Antibiotic resistance was based on disk diffusion method and blaZ and virulence-associated genes were studied by polymerase chain reaction. Penicillin resistance gene blaZ was detected in 35/37 (94.6%) of penicillin-resistant S. Aureus isolates. tst, lukPV, lukED, hla, hlb, and hld were observed in 5.4%, 2.7%, 89.2%, 70.3%, 73.0%, and 70.3% of the penicillin-resistant isolates, respectively, while eta, etb, lukM, and edin were not detected in any isolates. blaZ carried by penicillin-resistant S. Aureus isolates may be the main reason for phenotypic penicillin resistance. Virulence determinants encoded by lukED, hla, hlb, and hld genes may play important roles in bovine mastitis pathogenesis of penicillin-resistant S. Aureus in Gansu Province.