Virulence detection and molecular typing of Staphylococcus aureus isolated from rabbit in Sichuan area

Objective To understand genotyping characteristics, genetic variation and the distribution of virulence factors of Staphylococcus aureus isolated from rabbits in Sichuan area.

Method Forty-one S. aureus strains were isolated from rabbits in Sichuan area. The strains were identified for femB gene specifity. Methicillin-resistant S. aureus(MRSA) were screened out. Thirteen common virulence genes were detected using PCR. Genotyping characteristics were studied by using multilocus sequence typing (MLST) and pulsed field gel electrophoresis (PFGE).

Result There were 31 MRSA strains out of 41 S. aureus strains, and the detection rate was 75.61%. Totally nine virulence genes were detected, nuc, hla, eta and clfA genes existed in all strains, and the positive detection rates of sea, sec, see, hlb and PVL genes were 9.7%, 85.4%, 80.5%, 90.2% and 7.3%, respectively. MLST results showed that 41 S. aureus strains belonged to two sequence types (ST398, ST3320) and one clonal complex CC398. ST398 was the preponderant sequence type, and the proportion was 97.6%. PFGE analysis divided 41 S. aureus strains into 18 banding types, whereas strains from different regions had low variation in banding patterns.

Conclusion S. aureus strains isolated from rabbits in Sichuan area have high carrying rates of virulence factors, and therefore are potential security risk to rabbit farming industry. The genotyping analysis indicates that the prevalent strains of S. aureus isolated from parts of Sichuan Province have low genetic variation, and there are close genetic relationships among different strains.