耐甲氧西林凝固酶阴性葡萄球菌SCCmec分子流行病学调查研究

Study on SCCmecmolecular epidemiology of methicillin-resistant coagulase-negative Staphylococci

目的调查医院分离耐甲氧西林凝固酶阴性葡萄球菌(MRCNS)染色体mec基因盒的分布,为临床MRCNS分子流行病学调查提供合理的依据。方法收集医院2011年6月-2012年6月临床标本中分离的98株MRCNS,PCR检测mecA基因携带率,运用多重PCR检测SCCmec的基因型和亚型。结果 98株MRCNS中包括表皮葡萄球菌40株、溶血葡萄球菌32株、人葡萄球菌21株、科氏葡萄球菌5株;98株MRCNS经mecA基因检测均为阳性,其中40株耐甲氧西林表皮葡萄球菌中,SCCmecⅤ型24株占60.0%,SCCmecⅣ型9株占22.5%,SCCmecⅠ型6株占15%,1株未分型;在32株耐甲氧西林溶血葡萄球菌中,SCCmecⅤ型16株占68.75%,SCCmecⅣ型10株占31.25%,包括Ⅳa型5株,Ⅳb型5株;SCCmecⅢ型6株占15.0%;21株耐甲氧西林人葡萄球菌和5株耐甲氧西林科氏葡萄球菌均为SCCmecⅣ型。结论医院临床分离MRCNS的SCCmec型别主要以SCCmecⅤ和SCCmecⅣ为主;不同种类MRCNS所携带SCCmec的型别不同。

OBJECTIVE To investigate the distribution of chromosome mec gene cassette of coagulase-negative Staphylococci isolated from the hospital so to provide the reasonable basis for the clinical molecular epidemiological investigations of coagulase-negative Staphylococci.METHODS A total of 98 strains of coagulase-negative Staphylococci were isolated from various clinical specimens from Jun 2011 to Jun 2012.MecA gene was also determined by PCR.The antimicrobial susceptibility was measured by agar diffusion method.SCCmec typing was conducted using a novel multiplex PCR assay allowing for concomitant detection of methicillin resistance（mecA gene） to facilitate detection and classification of all currently described SCCmec typesⅠ,Ⅱ,Ⅲ,Ⅳa,b,c,d andⅤ.RESULTS MecA gene was positive in all the strains.Among the 98 methicillin-resistant isolates,there were 40 Staphylococcus epidermidis isolates,32 Staphylococcus haemolyticus isolates,21 Staphylococcus hominis isolates,and 5 Staphylococcus cohnii isolates.There were 24（60.0%） SCCmec Ⅴtype,9（22.5%） SCCmec Ⅳ type and 6（15.0%） SCCmec Ⅰ type among 40 S.epidermidis isolates,including 5 SCCmec IVa types and 4 SCCmec IVb types.A strain of S.epidermidis was untyped.There were 16（68.75%） SCCmec Ⅴtype,6（15.0%） SCCmec Ⅲ type,and 10（31.25%） SCCmec Ⅳ type in 32 methicillin-resistant S.hemolytic isolates,including 5 SCCmec Ⅳa types and SCCmec Ⅳb types.SCCmec Ⅴwas identified in all methicillin-resistant S.hominis and S.cohnii isolates.CONCLUSION SCCmecⅤ and SCCmec Ⅳ are the major genotypes of MRCNS in the hospital.There are several different SCCmec types among several kinds MRCNS.