耐甲氧西林金黄色葡萄球菌分型及流行现状

Genotype and epidemic status of Methicillin resistant Staphylococcus aureus in Hangzhou area

摘要:

【目的】研究杭州地区耐甲氧西林金黄色葡萄球菌(Methicillin-resistant Staphylococcus aureus，MRSA)的基因型别，探讨MRSA菌株流行变化趋势及进化特点，为该地区MRSA的进一步防治提供科学依据。【方法】对86株MRSA进行葡萄球菌盒式染色体SCCmec基因、spa基因分型，并开展多位点序列分型(Multi-locus sequence typing，MLST)，与国际上MRSA的流行型别进行比较，分析进化关系。【结果】86株MRSA共发现13个spa型(以t311型为主，占48.8%；其次为t6418型，占11.6%)；MLST分型共发现9个ST型(以ST5为主，占59.3%；其次为ST239，占16.3%)，经eBURST软件分析它们属于4个群(group 1、group 6、group 8、group 12)和8种克隆复合体(CC1、CC5、CC630、CC20、CC59、CC88、CC239、CC573)；SCCmec基因分型以SCCmecⅡ型为主，占61.6%；其次为SCCmecIII型，占22%；5株社区相关性MRSA (SCCmec-Ⅳ型)。其中第一流行克隆型为SCCmec-Ⅱ-ST5-t311-CC5 (占47.7%)、其次为SCCmec-III-ST239- t030/t037-CC239 (占12.8%)。【结论】SCCmec-Ⅱ-ST5-t311为杭州地区当前流行菌株；CA-MRSA菌株的出现，提示MRSA菌株有由医院向社区播散的趋势；此外，对新发展了单位点变体的菌株(SCCmec-Ⅰ-ST1921-t164-CC20和SCCmec-Ⅳ-ST965-t062-CC5)，应加强重视。

Abstract:

[Objective] To analyze the genotype of Methicillin-resistant Staphylococcus aureus (MRSA), discover the epidemiology and evolutionary pattern of MRSA and provide a scientific basis for prevention and control of MRSA in Hangzhou area. [Methods] In total 86 MRSA strains were characterized by spa typing, multi-locus sequence typing (MLST), staphylococcal cassette chromosome mec (SCCmec) typing. Results were compared with prevalent genotypes of MRSA reported worldwide to analyze the evolutionary relationships. [Results] The 86 MRSA isolates were classified into 13 spa types and 9 STs, which were further categorized into 4 groups and 8 clonal complex. The SCCmecⅡwas the predominant genotype (61.6%), followed by SCCmec-III (22%), 5 strains of CA-MRSA (SCCmecⅣ). SCCmec-II-ST5-t311-CC5 and SCCmec-III-ST239-t030/t037-CC239 were the main clones, representing for 47.7% and 12.8%, respectively. [Conclusion] SCCmec-Ⅱ-ST5-t311 was the most prevalent strain of MRSA in Hangzhou area. The emergence of CA-MRSA strains suggested that MRSA has spread from hospitals to community in Hangzhou. In addition, the strains (SCCmec-Ⅰ-ST1921-t164-CC20 and SCCmec-Ⅳ-ST965- t062-CC5) developed a new variant strain that needs more attention.