Abstract:

Objective To investigate the prevalence and genetic characteristic of Staphylococcus aureus with accessory gene regulator（agr） dysfunction. Methods A total of 1 238 isolates of Staphylococcus aureus were collected from 5 hospitals in Shanghai and Zhejiang. All the isolates were determined for methicillin resistance by cefoxitin disc,and were screened for agr dysfunction by determining δ-hemolysin production deficiency. The molecular characteristics of isolates with agr dysfunction were analyzed by agr typing,staphylococcal cassette chromosome mec（SCCmec） typing,staphylococcal protein A（spa） typing and multilocus sequence typing（MLST）. Results The 3.6%（45/1 238） of isolates were agr defective,which was more prevalent among methicillin-resistant Staphylococcus aureus（MRSA）[5.0%（28/565）] and methicillin-sensitiveStaphylococcus aureus（MSSA）[2.5%（17/673）]（P=0.023）. The analysis of genotyping displayed that ST5（CC5）-SCCmecⅡ-t002/t311/t2460-agr2 and ST239（CC8）-SCCmecⅢ-t037-agr1 were the predominant clones among agr defective MRSA isolates,and ST188（CC1）-t189-agr1 was the most abundant clone among agr defective MSSA isolates.Conclusions The rate of Staphylococcus aureus with agr dysfunction is low in Shanghai and Zhejiang,and its prevalence might be related to the spread of specific clones.

Key words: Staphylococcus aureus, Accessory gene regulator, Prevalence, Genetic characteristic