甲氧西林耐药金葡球菌（MRSA）耐药机制的研究  

Resistance mechanisms of MRSA to β-lactams

作　　者：魏瑾[1] 李家泰[1] 

机构地区：[1]北京医科大学临床药理研究所

出　　处：《中国抗生素杂志》1996年第2期110-120,共11页Chinese Journal of Antibiotics

基　　金：自然科学基金

摘　　要：用北京地区综合医院中分离的１９０株金葡球菌进行耐药机制研究。按照ＮＣＣＬＳ发表的ＭＲＳＡ标准，采用琼脂稀释敏感试验并以多聚酶链反应（ＰＣＲ）技术检测ｍｅｃＡ基因。１９０株金葡球菌中，８８株耐甲氧西林（ＭＩＣ≥１６ｍｇ／Ｌ），９１株耐苯唑西林（ＭＩＣ≥４ｍｇ／Ｌ），全部甲氧西林耐药金葡球菌和９８．８９％苯唑西林耐药金葡球菌为ｍｅｃＡ基因阳性。有１１株ｍｅｃＡ基因阳性金葡球菌对甲氧西林敏感，９株ｍｅｃＡ基因阳性金葡球菌对苯唑西林敏感。在８８株ＭＲＳＡ菌株中，７３．６３％为β－内酰胺酶产生菌，但克拉维酸只对低度耐药的ＭＲＳＡ菌株有影响，高度耐药的ＭＲＳＡ其ＭＩＣ值则不受克拉维酸的影响。这表明高度耐药ＭＲＳＡ所产生的β－内酰胺酶的作用还不清楚。群体分析结果发现所测试的全部菌株的耐药类型均为异质性耐药菌株。以上结果表明，我国临床分离的ＭＲＳＡ，其耐药机制主要是ｍｅｃＡ基因介异的。The mechanism of resistance of MRSA was studied on 190 strains of Staphylococcus aureus isolated from general hospitals in Beijing.The detection of MRSA was performed by using agar dilution sensitivity test according to thecrateria recommended by NCCLS and PCR techniqtie at molecular level for determination of mec A gene.In 190 strains of Staphylococcus aureus,88 and 91 strains were resistant to methicillin(MIC≥16mg/L)and oxacillin(MIC≥4mg/L),respectively.All of methicillin-resistant strains and 98.89%of oxacillin-resistant strains were mec A gene positive.The presence of mec A gene positive but methicillin sensitive(11 strains)or oxacillin sensitive(9 strains)indicated that it is necessary to establish a simple and rapid method for detecting mec A gene in clinic in order to make correct diagnosis of MRSA infections and to use antibiotics rationally in the treatment of infections caused by Staphylococcus aureus.Among 88 strains of MRSA,73.63%were β-lactamase producing strains.Only borderline methicillin resistant strains were affected by clavulanic acid,however,it was observed that the incubation of highly resistant strains of MRSA with or without clavtilanic acid in the medium caused no change of MICs.This indicated that the effect of β-lactamases produced in those highly resistant MRSA was not clear.Population analysis showed that the resistant pattern of all strains of MRSA tested was heterogenous.The above results suggested that the mechanism of resistance of MRSA isolated from clinic in China was mainly mediated by mec A gene.

关 键 词：金黄色葡萄球菌 MRSA 抗药性 

分 类 号：R378.11[医药卫生—病原生物学] R978.1[医药卫生—基础医学]