Department of Food Science, The Pennsylvania State University, University Park, PA 16802, USA.
Infect Genet Evol. 2012 Dec;12(8):1816-21. doi: 10.1016/j.meegid.2012.07.026. Epub 2012 Aug 26.
Methicillin-resistant Staphylococcus aureus (MRSA) remains a major threat to human populations worldwide. Knowing the extent of MRSA genetic diversity within a healthcare facility may provide important insights into the epidemiology of this important pathogen. MRSA isolates recovered from nasal swabs of patients entering the Intensive Care Unit of the Penn State Milton S. Hershey Medical Center, USA, from 2008 to 2009 were genotyped using Staphylococcal Cassette Chromosome mec (SCCmec), multilocus sequence typing (MLST) and a newly developed multi-virulence-locus sequence typing (MVLST) scheme. Sequence data for seven housekeeping genes (arcC, aroE, glpF, gmk, pta, tpi and yqiL) and six virulence genes (alt, essC, geh, hlgA, htrA and sdrC) were used for MLST and MVLST analyses, respectively. MLST identified 12 sequence types (STs) within the hospital isolates. One ST designated ST5 was the most common subtype (38.8%) followed by ST105 (22.4%) and ST8 (16.4%). In contrast, MVLST identified 29 STs (Virulence Types, VTs) from the same set of isolates, with VT6 (32.8%) being the predominant subtype followed by VT9 (8.9%) and VT2 (8.9%). Subsequent analysis of 25 MRSA isolates associated with an outbreak at a Pennsylvania state prison revealed all isolates were VT2 and SCCmec type IVa. These results suggest that a combination of MVLST and SCCmec typing may clarify the epidemiology of MRSA. Additional research with a more diverse set of strains and correlation with conventional epidemiologic data are needed to validate this new subtyping strategy.
耐甲氧西林金黄色葡萄球菌（MRSA）仍然是全球人类面临的主要威胁。了解医疗机构内 MRSA 遗传多样性的程度，可以为了解这种重要病原体的流行病学提供重要线索。从 2008 年至 2009 年，从美国宾夕法尼亚州立大学米尔肯·赫尔希医疗中心重症监护病房入院的患者的鼻腔拭子中回收耐甲氧西林金黄色葡萄球菌（MRSA）分离株，使用葡萄球菌盒染色体 mec（SCCmec）、多位点序列分型（MLST）和新开发的多毒力基因座序列分型（MVLST）方案对其进行基因分型。用于 MLST 和 MVLST 分析的序列数据分别来自七个管家基因（arcC、aroE、glpF、gmk、pta、tpi 和 yqiL）和六个毒力基因（alt、essC、geh、hlgA、htrA 和 sdrC）。MLST 在医院分离株中鉴定出 12 种序列型（ST）。一种 ST 被指定为 ST5，是最常见的亚型（38.8%），其次是 ST105（22.4%）和 ST8（16.4%）。相比之下，从同一组分离株中，MVLST 鉴定出 29 种 ST（毒力型，VT），其中 VT6（32.8%）是主要亚型，其次是 VT9（8.9%）和 VT2（8.9%）。随后对宾夕法尼亚州一所州立监狱暴发相关的 25 株 MRSA 分离株进行的分析显示，所有分离株均为 VT2 和 SCCmec 类型 IVa。这些结果表明，MVLST 和 SCCmec 分型的组合可能阐明 MRSA 的流行病学。需要使用更多多样化的菌株进行进一步研究，并与传统的流行病学数据进行关联，以验证这种新的亚型策略。
