从医院环境中流行的耐苯唑西林凝固酶阴性葡萄球菌克隆中鉴定一种新型 II 型葡萄球菌盒式染色体 mec 元件。
Characterization of a novel, type II staphylococcal cassette chromosome mec element from an endemic oxacillin-resistant Staphylococcus lugdunensis clone in a hospital setting.
机构信息
Department of Laboratory Medicine, Linkou Chang Gung Memorial Hospital, Taoyuan, Taiwan.
Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Taoyuan, Taiwan.
出版信息
J Antimicrob Chemother. 2019 Aug 1;74(8):2162-2165. doi: 10.1093/jac/dkz189.
BACKGROUND
Staphylococcus lugdunensis is a significant pathogen that causes community-acquired and nosocomial infections. The high prevalence of oxacillin-resistant S. lugdunensis (ORSL) is of major concern. Resistance to β-lactams is caused by acquisition of the staphylococcal cassette chromosome mec (SCCmec) element. The cassette is highly diverse, both structurally and genetically, among CoNS. Isolates carrying SCCmec II-ST6 are the major persistent clones in hospitals.
OBJECTIVES
To investigate the structure and evolutionary origin of a novel type II SCCmec element in an endemic ST6 S. lugdunensis clone.
METHODS
The structure of the SCCmec II element carried by ST6 strain CGMH-SL118 was determined by WGS and compared with those reported previously.
RESULTS
A novel 39 kb SCCmec element, SCCmecCGMH-SL118, with a unique mosaic structure comprising 41 ORFs integrated into the 3' end of the rlmH gene, was observed. Some regions of SCCmecCGMH-SL118 were homologous to SCCmec IIa of the prototype MRSA strain N315. The structure of SCCmecCGMH-SL118 was similar to that of SCCmec IIb of the MRSA strain, JCSC3063, mainly lacking the aminoglycoside resistance determinant pUB110 in the J3 region but containing the insertion sequence IS256 in the J2 region. Notably, SCCmecCGMH-SL118 deletions in the J1 region compared with SCCmec types IIa and IIb, and a high homology to SCCmec elements of Staphylococcus aureus JCSC4610 and Staphylococcus haemolyticus strain 621 were found.
CONCLUSIONS
The genetic diversity of the type II SCCmec element in ORSL suggests that CoNS is a potential reservoir for interspecies transfer of SCCmec to S. aureus in hospitals.
背景
金黄色葡萄球菌（Staphylococcus lugdunensis）是一种重要的病原体，可引起社区获得性和医院获得性感染。耐苯唑西林金黄色葡萄球菌（oxacillin-resistant S. lugdunensis，ORSL）的高流行率是一个主要关注点。β-内酰胺类药物的耐药性是由获得葡萄球菌盒染色体 mec（staphylococcal cassette chromosome mec，SCCmec）元件引起的。该盒在凝固酶阴性葡萄球菌（coagulase-negative staphylococci，CoNS）中具有高度的结构和遗传多样性。携带 SCCmec II-ST6 的分离株是医院中主要的持续性克隆。
目的
研究地方性 ST6 金黄色葡萄球菌克隆中一种新型 II 型 SCCmec 元件的结构和进化起源。
方法
通过 WGS 确定携带 ST6 菌株 CGMH-SL118 的 SCCmec II 元件的结构，并与先前报道的结构进行比较。
结果
观察到一种新型 39 kb SCCmec 元件 SCCmecCGMH-SL118，其具有独特的镶嵌结构，由 41 个 ORF 组成，整合到 rlmH 基因的 3'端。SCCmecCGMH-SL118 的一些区域与原型耐甲氧西林金黄色葡萄球菌（methicillin-resistant Staphylococcus aureus，MRSA）菌株 N315 的 SCCmec IIa 同源。SCCmecCGMH-SL118 的结构与 MRSA 菌株 JCSC3063 的 SCCmec IIb 相似，主要缺失 J3 区的氨基糖苷类耐药决定子 pUB110，但含有 J2 区的插入序列 IS256。值得注意的是，与 SCCmec IIa 和 IIb 相比，SCCmecCGMH-SL118 在 J1 区发生缺失，与金黄色葡萄球菌 JCSC4610 和溶血性葡萄球菌 621 株的 SCCmec 元件具有高度同源性。
结论
耐苯唑西林金黄色葡萄球菌中 II 型 SCCmec 元件的遗传多样性表明，凝固酶阴性葡萄球菌是医院内金黄色葡萄球菌种间 SCCmec 转移的潜在储库。
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