医院获得性耐甲氧西林金黄色葡萄球菌的分子流行病学研究

A molecular epidemiological analysis of hospital-acquired methicillin-resistant staphylococcus aureus

目的对2003年以来连续收集的122株耐甲氧西林金黄色葡萄球菌（MRSA）进行染色体盒mec元件（SCCmec）分型。方法用K-B法药敏试验常规进行抗生素敏感试验；按NCCLS标准，用琼脂板稀释法测定MRSA对苯唑西林的MIC值；用多重PCR方法对MRSA染色体盒mec元件的结构及其变异情况进行分型分析，对MRSA进行分子分型。结果122株MRSA对青霉素及环丙沙星均耐药，苯唑青霉素的MIC为64～1024mg／L，对红霉素、四环素、甲氧苄啶／磺胺甲嗯唑、克林霉素的耐药率分别为92％、95％、45％及47％，对万古霉素全部敏感；122株MRSA中有115株属于SCCmec-Ⅲ型，4株属于SCCmec-ⅢA亚型，1株属于SCCmec-Ⅳ型，1株属于SCCmec-Ⅰ型，1株属于未定型株（NT SCCmec型）。结论多数MRSA菌株对所用抗生素呈多药耐药；用多重PCR方法对MRSA进行分子分型，是基于对MRSA耐药基因mec A的结构进行分析的一种分型方法，方便快速，结果可靠，是MRSA分子分型的有效工具，对从基因水平阐述隐含的耐药机制及MRSA的耐药性变迁具有重要价值。

Objective To genotype 122 strains of methicillin - resistant Staphylococcus aureus （MRSA） collected consecutively in the year of 2003 in our hospital. Methods Antimicrobial test was performed by K - B method. MICs of oxacillin were 64 - 1024 μg/ml. Resistance to erythromycin, tetracycline, trimethoprim - sulfamethoxazole, clindamycin were 92% ,95% ,45% and 47%, respectively. All MRSA strains were susceptible to vancomycin and resistant to ciprofloxacin and penicillin. Multiplex PCR was used to genotype Staphylococcal chromosomal cassette mec （SCCmec） element and its variants. Results Among 102 stains of M RSA, the genotypes were as follows： SCCmec -Ⅲ（ 115 strains）, SCCmec - ⅢA （4 strains ）, SCCmec - Ⅳ（ 1 strains ）, SCCmec -Ⅰ（ 1 strains） and nontypeable SCCmec type （ NT, 1 strains ）. Conclusion Most MRSA strains were multi - resistant. Genotyping MRSA with multi - plex PCR is based on mecA gene of MRSA. It is a rapid and simple MRSA genotyping method. It is important in the evolvement of MRSA and investigation of antimicrobial resistance mechanism of MRSA.