鉴定耐苯唑西林凝固酶阴性葡萄球菌中两种新型的葡萄球菌盒式染色体 mec 元件的变体。

Characterization of two novel variants of staphylococcal cassette chromosome mec elements in oxacillin-resistant Staphylococcus lugdunensis.

机构信息

Department of Laboratory Medicine, Linkou Chang Gung Memorial Hospital, Taoyuan, Taiwan.

Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang Gung University, Taoyuan, Taiwan.

出版信息

J Antimicrob Chemother. 2017 Dec 1;72(12):3258-3262. doi: 10.1093/jac/dkx291.

DOI:10.1093/jac/dkx291

PMID:28962025

Abstract

OBJECTIVES

Staphylococcus lugdunensis, a species of CoNS, has become an important hospital pathogen because of increasing resistance to β-lactam antibiotics such as methicillin and oxacillin. Methicillin resistance is mainly due to the acquisition of the staphylococcal cassette chromosome (SCC) mec (SCCmec). Little is known about the structure of SCCmec in methicillin- or oxacillin-resistant CoNS.

METHODS

WGS was performed to determine the structure of SCCmec elements of two clinical S. lugdunensis isolates: CMUH-22 and CMUH-25.

RESULTS

These elements were found to be flanked by DRs and IRs with unique mosaic structures and a common integration site in the 3' end of the rlmH gene. The sequences of the regions located between rlmH and the ISSau4-like transposase genes of both elements were similar to those of SCCmec Vt of Staphylococcus aureus PM1. The SCCmec (type V, 5C2&4) of CMUH-25 harboured a novel ccrC complex and a C2-like mec complex in opposite orientations, similar to the type V SCCmec of S. aureus WIS. The sequences of the ccrA4B4 genes and J1 and J2 regions of CMUH-25 were similar to those of the SCC element of Staphylococcus haemolyticus NCTC 11042. In contrast, portions of the sequence of the J1 region of type Vt (5C2) SCCmec in strain CMUH-22 were highly similar to portions of those of Staphylococcus epidermidis RP62A and the composite SCCmec type V of S. aureus WAMRSA40.

CONCLUSIONS

These observations suggest that the SCCmec elements of CMUH-25 and CMUH-22 evolved separately and assembled through different recombination events.

摘要

目的

凝固酶阴性葡萄球菌（CoNS）中的金黄色葡萄球菌亚种（S. lugdunensis）由于对β-内酰胺类抗生素（如甲氧西林和苯唑西林）的耐药性不断增加，已成为一种重要的医院病原体。耐甲氧西林主要是由于获得了葡萄球菌盒式染色体（SCCmec） mec（SCCmec）。关于耐甲氧西林或耐苯唑西林 CoNS 中 SCCmec 的结构知之甚少。

方法

对 2 株临床分离的 S. lugdunensis 菌株 CMUH-22 和 CMUH-25 的 SCCmec 元件进行 WGS 分析。

结果

发现这些元件两侧是 DR 和 IR，具有独特的镶嵌结构和 rlmH 基因 3'端的共同整合位点。这两个元件中位于 rlmH 和 ISSau4 样转座酶基因之间的区域序列与金黄色葡萄球菌 PM1 的 SCCmec Vt 相似。CMUH-25 的 SCCmec（类型 V，5C2&4）携带一个新的 ccrC 复合物和一个与金黄色葡萄球菌 WIS 类型 V SCCmec 相似的 C2 样 mec 复合物。CMUH-25 的 ccrA4B4 基因和 J1 和 J2 区域的序列与溶血性葡萄球菌 NCTC 11042 的 SCC 元件相似。相比之下，CMUH-22 株 5C2 型（5C2）SCCmec 的 J1 区域部分序列与表皮葡萄球菌 RP62A 和金黄色葡萄球菌 WAMRSA40 的复合 SCCmec 类型 V 的部分序列高度相似。