徐州地区116株MRSA耐药性分析与分子流行病学调查

Antimicrobial resistance and molecular epidemiology of 116 strains of methicillin-resistant Staphylococcus aureuin Xuzhou area

目的了解耐甲氧西林金黄色葡萄球菌(MRSA)感染现状和耐药机制,为临床合理用药提供依据。方法收集徐州地区2012—2015年各类标本中分离的金黄色葡萄球菌(SA),用头孢西丁纸片扩散法初筛MRSA菌株,扩增mecA基因进行确认,K-B法检测MRSA对药物的敏感性,E-test法测定万古霉素的最低抑菌浓度(MIC),采用多重PCR进行葡萄球菌染色体mec(SCCmec)基因分型。结果 2012—2015年210株SA共检出MRSA116株,其中mecA基因阳性114株,MRSA总检出率为55.24%。MRSA对万古霉素、奎奴普丁/达福普汀、替考拉宁和利奈唑胺的敏感率均为100%,对氯霉素和呋喃妥因的耐药率最低,分别为15.52%、1.72%,MRSA对10种抗菌药物的耐药率>80%;MRSA对青霉素类、氨基糖苷类、红霉素、喹诺酮类、磺胺类、利福平、四环素、克林霉素的耐药率高于甲氧西林敏感金黄色葡萄球菌(MSSA)。2012—2015年万古霉素对MRSA的MIC均为1.0μg/mL,MIC90均为1.5μg/mL,2015年发现1株MRSA的万古霉素MIC为2.0μg/mL。116株MRSA分型结果显示,SCCmecII型11株(9.48%),SCCmecIII型85株(73.28%),SCCmecIV型4株(IVa和IVb型各2株,均为1.72%),未分型MRSA16株(13.79%),未检出SCCmecI和V型。结论 MRSA呈严重的多重耐药,对万古霉素MIC无漂移,临床MRSA分离株以SCCmecIII型为主,临床应采取感染控制措施,控制MRSA感染。

ObjectiveTo investigate infection status and antimicrobial resistance mechanism of methicillinresistant Staphylococcus aureus（MRSA）,and provide reference for the rational antimicrobial use in clinic. MethodsStaphylococcus aureus （SA） isolated from various specimens in Xuzhou area in 2012-2015 were collected, MRSA strains were preliminarily screened by cefoxitin disk diffusion method, and confirmed by amplification of mecA gene, antimicrobial resistance of MRSA was determined by KirbyBauer method, minimal inhibitory concentration （MIC） was measured by Etest method, genotypes of staphylococcal chromosomal cassette mec（SCCmec） were determined by multiplex PCR. ResultsA total of 116 strains of MRSA were identified among 210 SA strains in 2012-2015,114 of which were positive for mecA gene, the total detection rate of MRSA was 55.24%. Susceptibility rates of MRSA to vancomycin, quinupristin/ dalfopristin, and linezolid were all 100%, resistance rates of MRSA to chloramphenicol and furantoin were both low, which were 15.52% and 1.72% respectively, resistance rates of MRSA to 10 kinds of antimicrobial agents were all〉80%; resistance rates of MRSA to penicillins, aminoglycosides, macrolides, quinolones, sulfanilamide, rifampicin, tetracycline, and clindamycin were all higher than methicillinsensitive Staphylococcus aureus（MSSA）. MICs of vancomycin to MRSA in 2012-2015 were all 1.0 μg/mL,MIC90 were all 1.5 μg/mL, one MRSA isolate was with a vancomycin MIC of 2.0 μg/mL in 2015. MRSA typing results of 116 MRSA isolates showed that SCCmec II, SCCmec III, and SCCmec IV accounted for 9.48%（n=11）, 73.28%（n=85）,and 1.72%（Iva, n=2; IVb, n=2） respectively, 13.79%（n=16） of MRSA isolates were nontypeable, SCCmec I and SCCmec V type strains were not found. ConclusionMRSA is seriously multidrugresistant,the drift has not been discovered in MIC value of vancomycin against MRSA, the major SCCmec genotype of MRSA is SCCmec III, infection control measures should be taken to control MRSA infection.