[Rapid detection of oxacillin and erythromycin resistance genes in Staphylococcus aureus using multiplex PCR]

To establish a rapid multiplex PCR (MPCR) detection system of oxacillin and erythromycin resistance genes in Staphylococcus aureus (S. aureus) and evaluate the genotype distribution of the genes associated to mecA, ermA and ermC resistance in Guangzhou.

The S. aureus strains were identified and susceptibility tests were performed using VITEK-60 or PHOENIX-100 system. The inducible resistance to clindamycin of strains with of erythromycin resistance was conducted using D-test, and the MPCR system of for detecting the antibiotic resistance genes was optimized.

The MPCR assay for detecting the resistance genes was constructed successfully. According to the results of MPCR, the positivity rates for mecA, ermA and ermC genes among the 124 strains of S. aureus isolated from clinical samples were 56.5%, 50% and 33.9%, respectively. Good correlation was observed between the antibiotic resistance phenotypes and the S. aureus genotypes. mecA were detected in all the methicillin-resistant S. aureus strains, and ermA and/or ermC in 97.7% of the S. aureus strains with erythromycin resistance.

This MPCR system allows rapid and reliable analysis of antibiotic resistance genotypes of S. aureus isolated from clinical samples. mecA, ermA, and ermC genes are among the predominant genetic determinants for the resistance to oxacillin and erythromycin in S. aureus isolates in Guangzhou.