Department of Microbiology, JIPMER, Puducherry, India.
J Med Microbiol. 2019 May;68(5):720-727. doi: 10.1099/jmm.0.000977. Epub 2019 Apr 17.
Methicillin-resistant Staphylococcus aureus (MRSA) can be classified into hospital-acquired MRSA (HA-MRSA) and community-associated MRSA (CA-MRSA), based on the associated epidemiological risk factors and their SCCmec types. We therefore studied the diversity and distribution of SCCmec elements among MRSA isolates in our region and also evaluated SCCmec typing as a tool for the classification of MRSA.
Two hundred isolates of MRSA obtained from various clinical specimens were included. The clinical and demographic details of the patients and the epidemiological risk factors for MRSA acquisition were documented. Multiplex PCR was optimized for all the major SCCmec types (I to V). Subtyping of SCCmec type IV (IVb, IVc, IVd, IVh) was carried out by simplex PCR.
Based on epidemiological criteria, CA-MRSA constituted 57 % (114/200) of the the test isolates and HA-MRSA made up 43 % (86/200). The predominant SCCmec type found in our study was type III (62%), followed by type V (52.5%) and type I (47.5%), while type II was carried by a single isolate. Of the 200 isolates, 118 carried multiple SCCmec types and 3 were non-typable.
The existence of multiple SCCmec types in individual MRSA isolates resulted in our inability to categorize many of these isolates as either CA-MRSA or HA-MRSA as defined by the SCCmec type criterion.
The major limitation of the study was that the SCC mec element of MRSA isolates exhibiting multiple types was not sequenced and hence this finding could not be confirmed.
耐甲氧西林金黄色葡萄球菌（MRSA）可根据相关的流行病学危险因素及其 SCCmec 类型分为医院获得性 MRSA（HA-MRSA）和社区相关性 MRSA（CA-MRSA）。因此，我们研究了本地区 MRSA 分离株中 SCCmec 元素的多样性和分布情况，并评估了 SCCmec 分型作为 MRSA 分类的一种工具。
纳入了 200 株来自各种临床标本的 MRSA 分离株。记录了患者的临床和人口统计学资料以及 MRSA 获得的流行病学危险因素。针对所有主要 SCCmec 类型（I 至 V）对多重 PCR 进行了优化。通过单重 PCR 对 SCCmec 类型 IV（IVb、IVc、IVd、IVh）进行亚分型。
根据流行病学标准，CA-MRSA 构成了检测分离株的 57%（114/200），HA-MRSA 占 43%（86/200）。本研究中发现的主要 SCCmec 类型是 III 型（62%），其次是 V 型（52.5%）和 I 型（47.5%），而 II 型仅由单个分离株携带。在 200 个分离株中，有 118 个携带多种 SCCmec 类型，有 3 个分离株无法定型。
由于个体 MRSA 分离株中存在多种 SCCmec 类型，我们无法根据 SCCmec 类型标准将许多这些分离株归类为 CA-MRSA 或 HA-MRSA。
本研究的主要局限性在于，未能对表现出多种类型的 MRSA 分离株的 SCC mec 元素进行测序，因此无法证实这一发现。
