agr功能缺陷金黄色葡萄球菌流行及遗传学特征

Prevalence and genetic characteristic of Staphylococcus aureus with agr dysfunction

目的研究金黄色葡萄球菌附属基因调节子(agr)功能缺陷金黄色葡萄球菌的流行及遗传学特征。方法收集上海市和浙江省5家医院临床分离的1238株金黄色葡萄球菌,采用头孢西丁纸片法确定其对甲氧西林的耐药性;采用δ溶血活性检测筛选agr功能缺陷菌株,应用agr分型、葡萄球菌盒式染色体mec(SCCmec)分型、金黄色葡萄球菌蛋白A基因(spa)分型和多位点序列分型(MLST)确定相关菌株的分子特征。结果agr功能缺陷金黄色葡萄球菌总流行率为3.6%(45/1238),其中耐甲氧西林金黄色葡萄球菌(MRSA)的检出率[5.0%(28/565)]显著高于甲氧西林敏感金黄色葡萄球菌(MSSA)[2.5%(17/673)](P=0.023)。基因分型结果显示,agr功能缺陷MRSA以ST5(CC5)-SCCmecⅡ-t002/t311/t2460-agr2和ST239(CC8)-SCCmecⅢ-t037-agr1为主,而MSSA主要为ST188(CC1)-t189-agr1。结论沪浙地区agr功能缺陷金黄色葡萄球菌并不常见,其流行可能与特定型别克隆株的传播有关。

Objective To investigate the prevalence and genetic characteristic of Staphylococcus aureus with accessory gene regulator(agr)dysfunction.Methods A total of 1238 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 determiningδ-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%(45/1238)of isolates were agr defective,which was more prevalent among methicillin-resistant Staphylococcus aureus(MRSA)[5.0%(28/565)]and methicillin-sensitive Staphylococcus 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.