重症医学科内耐甲氧西林金黄色葡萄球菌的分子流行病学调查

Investigation of molecular epidemiology of methicillin-resistant staphylococcus aureus in department of critical care medicine

目的了解重症医学科（ICU）内耐甲氧西林金黄色葡萄球菌（MRSA）的耐药性、同源性等分子流行病学特点。方法收集鉴定2010年10月至2011年12月全国10家医院ICU患者痰培养的MRSA菌株149株。检测其对18种抗菌药物的耐药性，利用脉冲场凝胶电泳（PFGE）技术进行同源性分析，并应用多位点序列分析（MLST）技术进一步进行序列型（ST）分型。结果149株MRSA对万古霉素、达托霉素及利奈唑胺100％敏感，复方新诺明耐药率约在0—11．1％之间；利福平在2家医院耐药率〈25％；庆大霉素、莫西沙星的耐药率除3家在50％～70％外均在80％以上；t3-内酰胺类的耐药率高达100％。149株MRSA中，PFGE主要型别为J（28．9％）、C（19．5％）、G（10．7％）、F（8．0％）4型，J、C、G3型主要分布在北方地区，而F型只分布在贵阳地区。MLST分型：最终确定了8个ST型别，其中以ST-239为主（67株，45．0％），在南北方均有分布；其次为ST-5（54株，36．2％），主要分布在东北地区（x2=26．42，P〈0．01）。结论ICU内MRSA对万古霉素、达托霉素及利奈唑胺仍100％敏感；MRSA的区域性同源性较高，可能存在同源性播散性情况，需要继续加强监测并采取有效的院感控制措施避免MRSA同源暴发流行。

Objective To investigate the feature of antimicrobial resistance, homology and other molecular epidemiology of methicillin-resistant staphylococcus aureus（MRSA） in Department of Critical Care Medicine（ICU）. Methods From October 2010 to December 2011,149 strains of MRSA were collected and identified through sputum culture of patients from 10 ICUs of 10 teaching hospitals distributed in 9 chinese central city of China. Susceptibility testing to 18 kinds of antibiotic was performed,the method of pulsed field gel electrophoresis （PFGE） was used to analyze the homology, and the technique of muhilocus sequencing typing （MLST） was used to identify the sequence type （ST）. Results Antibiotic susceptibility testing implied that vancomycin, daptomycin and linezolid are 100% sensitive to collected 149 strains of MRSA. Cotrimoxazole resistance rate is about 0 - 11.1% . Rifampicin resistant rate was less than 25% in 2 hospitals ; the resistance rate of gentamicin and moxifloxacin were more than 80% besides of 50% to70% in 3 hospitals; beta lactam resistant rate was 100%. In 149 strains of MRSA, the main types of PFGE were J （28.9%）, C （19.5%）, G （10.7%）, F （8%）types. J, C, Gtypes mainly distributed in the North, while the F type only distributed in the Guiyang region. The MLST type： 8 ST types were determined ultimately. In which, was dominated by ST-239 （67 strains, 45% ）, distributed in the South and North; followed by ST-5 （ 54 strains, 36. 2% ）, mainly in the Northeast region （x2 = 26.42, P 〈 0.01 ）. Conclusions Vancomycin, daptomycin and linezolid are 100% sensitive drugs to MRSA in ICU; Higher regional homology for MRSA were observed and it is probably that homologic disseminated infection exited in ICU. It is necessary to enhance continuous monitoring and take effective nosocomial infection control action to avoid MRSA homologic outbreak.