2008-2011年四年我院560株MRSA的耐药性分析及分子分型

Genotypes and antimicrobial resistance of 560 methicillin-resistant Staphylococcus aureus from 2008 to 2011

目的了解我院2008年到2011年临床分离的560株耐甲氧西林金黄色葡萄球菌(MRSA)的葡萄球菌盒染色体mec(SCCmec)分型、杀白细胞素(PVL)阳性率及其耐药性分析,为临床用药及流行病学调查提供依据。方法收集我院2008年到2011年MRSA共560株,用聚合酶链反应(PCR)检测其mecA基因、SCCmec分型及PVL基因,应用微量肉汤法检测MRSA对环丙沙星、庆大霉素、四环素、复方新诺明、青霉素G、克林霉素、红霉素、利奈唑胺、莫西沙星、苯唑西林、奎奴普丁/达福普汀、利福平和万古霉素13种抗生素的药物敏感性,采用头孢硝噻吩纸片法检测β内酰胺酶。结果 560株mecA基因均为阳性;SCCmec分型Ⅰ型占0.4%,Ⅱ型占12.1%,Ⅲ型占50.9%,Ⅳa型占3.9%,Ⅴ型占3.6%,剩下的未能分型;PVL基因阳性菌株23株,占4.1%;MRSA对青霉素G、苯唑西林及β内酰胺类抗生素几乎百分百耐药,而对环丙沙星、庆大霉素、四环素、克林霉素、红霉素和莫西沙星耐药性较高,分别为79.4%、71.3%、76.9%、73.8%、84.3%和73.2%,其对复方新诺明、Linezolid、奎奴普丁/达福普汀耐药性较低,分别为24.3%、0.2%、0.9%,未检出万古霉素耐药菌株。结论我院2008-2011年MRSA的SCCmec分型主要以Ⅲ型为主,占50.9%,且具有多重耐药特性,来源多为医院获得性感染,社区相关性MRSA菌株占少量。

Objective To investigate the genotypes of staphylococcal chromosome cassette mec( SCCmec) and Panton-Valentine Lenkocidin( PVL) gene,and antimicrobial resistance of 560 clinical isolated strains of methicillin-resistant Staphylococcus aureus( MRSA) from 2008 to 2011 in our hospital,and provide evidence for clinical medication and epidemiological investigation. Methods The 560 clinical isolated strains were collected in our hospital from 2008 to 2011. The polymerase chain reaction( PCR) was used to detect the mecA gene,SCCmec genotype and PVL gene. Antimicrobial susceptibility to 13 antibiotics were detected by broth microdilution,and beta lactamase was detected by nitrocefin paper method. Results The 560 isolates of MRSA were all mecA gene positive. Most of the strains were SCCmec type III( 50. 9%),with SCCmec type I accounting for 0. 4%,SCCmec type II 12. 1%,SCCmec type IVa 3. 9%,and SCCmec type V 3. 6%; the others remained ungenotyped. 23 strains( 4. 1%) were PVL gene positive. The resistance rates to penicillin G,oxacillin and beta lactam antibiotics were nearly 100%,and to ciprofloxacin,gentamycin,tetracycline,erythromycin,clindamycin,and moxifloxacin were over 70%,while the resistance rates to cotrimoxazole,Linezolid,and Guinupristin / Dalfopristin were low( 24. 3%,0. 2% and 0. 9%,respectively). No vancomycin resistant strains were detected. Conclusion The genotype of SCCmec of MRSA in our hospital was mainly SCCmec type III( 50. 9%); most of the strains were multi-drug resistant and hospital-acquired,while community-acquired MRSAs were less common.