Development of multiplex PCR system for rapid detection of genes encoding amino-glycoside resistance in Staphylococcus aureus / 中国感染与化疗杂志

ABSTRACT

Objective The rapid multiplex PCR (MPCR) system for detection of genes encoding aminoglycoside resistance in Staphylococcus aureus was developed. The distribution of antibiotic resistant genes acc(6')-Ie+aph(2″), aph(3')-Ⅲa and ant(4')-Ia in Guangzhou was analyzed using the established system.Methods S. aureus strains were identified and susceptibility tests were performed using VITEK-60 or PHOENIX-100 system as recommended by the manufacturer. Aminoglycoside resistance was determined by disk diffusion method. MPCR system for detection of antibiotic resistance genes was optimized.Results The MPCR assay was established successfully. The prevalence of acc(6')-Ie+aph(2″), aph(3')-Ⅲa and ant(4')-Ia in the 124 clinical S. aureus isolates was 62.1%, 32.3% and 1.6%, respectively as analyzed by MPCR. Good correlation between antibiotic resistance phenotypes and genotypes was observed. One or more of the genes encoding aminoglycoside modifying enzymes could be detected in all gentamicin- or netilmicin- or amikacin-resistant isolates. The acc(6')-Ie+aph(2″) gene was identified in 72 of 74 mecA-positive isolates.Conclusions This MPCR system could be used for rapid and reliable analysis of the antibiotic-resistant genotypes of clinical S. aureus isolates. The gene acc(6')-Ie+aph(2″) may be the predominant determinant of aminoglycoside resistance, followed by gene aph(3')-Ⅲa. The prevalence of ant(4')-Ia gene is relatively low.