我国猪源甲氧西林耐药金黄色葡萄球菌的分离与分子分型研究

Isolation and characterization of methicillin-resistant Staphylococcus aureus from swine in China*

目的:近期研究发现,养殖生猪是甲氧西林耐药金黄色葡萄球菌(Methicillin-resistant Staphylococcus aureus,MRSA)的重要宿主,本研究旨在阐明MRSA在我国养殖生猪中的分布和遗传学特征。方法:从我国河北、陕西、湖北和四川的生猪养殖场或屠宰场采集生猪鼻咽部拭子进行MRSA分离和鉴定,并对分离株进行了表型和基因型的分析。结果:从569份生猪鼻咽部拭子中分离出58株MRSA,这些菌株的耐药表型主要有2种:CIP-CLI-ERY-FOX-GEN-TET-CHL和CIP-CLI-ERY-FOX-GEN-TET;所有菌株均属于spa t899和SCCmecⅢ型,未检出PVL基因。经多位点测序分型分析后发现,我国猪源MRSA菌株以ST9型为主;脉冲场电泳(Pulssed Gel Electrophoresis,PFGE)分型分析显示,猪源MRSA菌株中存在优势的PFGE基因型和基因簇。结论:在我国养殖生猪中广泛存在ST9-spa899-SCCmecⅢ型MRSA菌株,这些菌株可能成为社区MRSA感染的新来源。

Objectives：Swine has recently emerged as an important reservoir of methicillin-resistant Staphylococcus aureus（MRSA）and the objectives of this study were to investigate the distribution pattern of swine MRSA isolates and their phenotypical and genetic characteristics.Methods： Nasal swabs of animals workers were collected from Hebei,Shaanxi,Hubei and Sichuan province,MRSA isolates were recovered and comprehensive genotypic and phenotypic characterization were carried out.Results：Totally,58 MRSA isolates were recovered from 569 swine samples.Two predominant antimicrobial resistant profiles as CIP-CLI-ERY-FOX-GEN-TET-CHL and CIP-CLI-ERY-FOX-GEN-TET were identified.All recovered MRSA isolates shared identical spa type（t899）and SCCmec element（group Ⅲ）and were Panton Valentine leukocidin negative.After multilocus sequence typing analysis,ST9 was identified as the dominant sequence type.One dominant pulsed field gel electrophoresis cluster and a dominant strain type were identified.Conclusions： This study provided critical information about the swine originated MRSA isolates in China,which might become a new reservoir of community-acquired MRSA.