浙江省耐甲氧西林金黄色葡萄球菌分子分型及耐药性分析

目的探讨浙江省分离的耐甲氧西林金黄色葡萄球菌（MRSA）的分子分型及菌株的耐药性。方法连续收集2009年1月至2010年12月浙江省11家三级甲等医院临床分离的MRSA147株。采用琼脂稀释法对13种抗菌药物进行最小抑菌浓度（MIC）测定。通过多位点序列分型（MLST）、SCCmec分型和spa分型进行菌株同源性分析，并比较不同分型菌株的耐药谱。利用辛普森指数计算三种分型方法的分辨率并进行比较。结果147株MRSA菌株共分为14种ST型，其中ST239（75株）、ST5（24株）和ST59（23株）为主要流行克隆；SCCmec分型以Ⅲ型为主（76株），其次是Ⅳ型（32株）、Ⅱ型（24株）和V型（9株），6株菌株无法分到已知型；spa基因分型被分为23种，其中以t030、t437、t002和t037菌株数最多，分别为57，17，15和12株。药敏结果显示，MRSA菌株除对利奈唑胺、替考拉宁、万古霉素和去甲万古霉素敏感外，对其他常用抗菌药物的耐药率均很高，尤其是主要流行克隆ST239以及SCCmecⅢ型菌株耐药情况严重。三种分型方法的分辨率分别为0．6885，0．6577和0．8165，其中spa分型方法对菌株的区分能力更强。结论浙江省临床分离的MRSA菌株存在主要流行克隆ST239-SCCmecⅢ-t030-MRSA，耐药形势严峻，应加强院内耐药菌株的监测。

Molecular typing and drug resistance of methicillin-resistant Staphylococcus aureas in Zhejiang province

Objective To investigate molecular types and drug resistance of methicillin-resistant Staphylococcus aureus （MRSA） in Zhejiang province. Methods One hundred and fourty-seven clinical MRSA isolates were collected from 11 grade A tertiary hospitals during January 2009 and December 2010 in Zhejiang province. Minimal inhibitory concentrations （MICs） of 13 antimicrobial agents were determined by agar dilution. Muhilocus sequence typing （MLST） , staphylococcal cassette chromosome mec （SCCmec） typing and spa typing were used to examine the homology of the strains, and drug resistance patterns were compared among different molecular types. Simpson index was used to determine the discriminatory power of three typing methods. Results Fourteen STs were identified in 147 MRSA isolates, of which ST239 （75 isolates）, ST5 （24 isolates） and ST59 （23 isolates） were the most prevalent clones. Four SCCmec types （types Ⅱ to V） were identified in 141 isolates, and 6 isolates were not typed. SCCmec type Ⅲ was the predominant type （76 isolates）, which was followed by type Ⅳ （32 isolates）, type U （24 isolates） and type V （9 isolates）. All MRSA isolates yielded 23 spa types, in which tO30 （57 strains） , t437 （17 strains）, t002 （15 strains） and t037 （12 strains） were the predominant spa types. MRSA strains were sensitive to linezolid, teicoplanin, vancomycin and norvancomycin, but were highly resistant to other antibacterialagents, especially in strains carrying clone ST239 or of SCCmec type Ⅲ. The discriminatory power of MLST, SCCmec and spa typing were 0. 6885, 0. 6577 and 0. 8165, respectively. Conclusion The predominant clone of MRSA strains in Zhejiang province was ST239-SCCmecm-t030-MRSA, and these strains are highly resistant to most antibacterial agents, so that the surveillance of MRSA in hospital should be strengthened.