2017—2018年江西地区耐甲氧西林金黄色葡萄球菌的分子流行特征

Molecular epidemiological characteristics of methicillin-resistant Staphylococcus aureus in Jiangxi Province from 2017 to 2018

目的了解江西各地区耐甲氧西林金黄色葡萄球菌(MRSA)的分子特征及主要流行克隆型别,探讨流行克隆可能的竞争优势,为后续的机制研究提供资料。方法收集2017年1月-2018年12月江西省11个地市11所三甲医院临床分离的MRSA,同时应用mecA+femB双重PCR法鉴定为MRSA菌株后纳入研究,应用spa分型、SCCmec分型、PFGE和MLST进行分子分型,采用PCR方法检测杀白细胞素(PVL)毒力基因。结果spa分型主要为t437(74株,占31.22%)、t030(32株,占13.50%);不同地区的spa型存在很大差异,南昌地区以t030为主,其余地区以t437为主。SCCmecIVa为优势型别(占66.67%),SCCmecⅢ占15.19%;除南昌地区以SCCmecⅢ为主要型别外(占59.38%),其余各地区均以SCCmecIVa为主要优势型别。经PFGE分型和MLST,优势克隆型别为ST239、ST59、ST1和ST338;优势克隆群为CC239、CC59和CC1。共检出32株(13.19%)PVL阳性菌,其中鹰潭地区PVL检出率最高(29.63%,8/27),其次为景德镇地区(26.32%,5/19)。结论ST59-MRSA-IVa-t437为江西地区的主要优势流行克隆型,且各地区之间存在一定程度的克隆播散。ST239-MRSA-Ⅲ-t30为次要优势流行克隆型,主要在南昌地区多见,其他地区散发。江西地区PVL阳性菌株的主要型别为ST59-MRSA-t437-IVa型。

Objective To understand the molecular characteristics and main epidemic clone types of methicillin-resistant Staphylococcus aureus(MRSA)in different regions of Jiangxi Province,explore the possible competitive advantages of epidemic clone,provide information for the subsequent study on mechanism.Methods Clinical isolates of MRSA from11 hospitals in 11 cities of Jiangxi Province between January 2017 and December 2018 were collected,MRSA strains identified by mecA+femB double polymerase chain reaction(PCR)were included in study,molecular typing was performed by spa,SCCmec,pulsed-field gel electrophoresis(PFGE)and multilocus sequence typing(MLST),virulence genes of Panton-Valentine leukocidin(PVL)were detected by PCR method.Results The main types of spa were t437(74 strains,31.22%)and t030(32 strains,13.50%);there were significant differences in spa types among different regions,except for t030 in Nanchang region,t437 was the dominant type in other regions.SSCCmec IVa was the dominant type(66.67%),SCCmecⅢaccounted for 15.19%;except for SCCmecⅢin Nanchang(59.38%),SCCmec IVa was the dominant type in other regions.The dominant clone types detected by PFGE and MLST were ST239,ST59,ST1 and ST338;and the dominant clone groups were CC239,CC59 and CC1.A total of 32 strains(13.19%)of PVL-positive bacteria were detected,the highest detection rate of PVL was found in Yingtan region(29.63%,8/27),followed by Jingdezhen region(26.32%,5/19).Conclusion ST59-MRSA-IVa-t437 is the predominant epidemic clone type in Jiangxi,and there is a certain degree of clonal dissemination among different regions.ST239-MRSA-III-t30 is the secondary dominant epidemic clone type,which is mainly found in Nanchang and sporadic in other regions.The main type of PVL-positive strains in Jiangxi is ST59-MRSA-t437-IVa.