9株分离自住院患者的CA-MRSA基因型菌株的分子特征及耐药性研究

doi:10.16150/j.1671-2870.2021.01.010

摘要/Abstract

摘要：

目的:分析分离自住院患者的社区获得耐甲氧西林金黄色葡萄球菌（community-associated methicillin resistant Staphylococcus aureus, CA-MRSA）菌株的分子水平特征和耐药性,为监测CA-MRSA的流行及治疗、控制提供依据。方法:收集2014年4月到2015年12月期间从住院患者标本（入院后48 h内获取）中分离的金黄色葡萄球菌,检测其mecA基因以区分耐甲氧西林金黄色葡萄球菌（methicillin resistant Staphylococcus aureus, MRSA）与甲氧西林敏感的金黄色葡萄球菌（methicillin sensitive Staphylococcus aureus, MSSA）,并根据葡萄球菌盒式染色体基因mec（Staphylococcal cassette chromosome mec, SCCmec）的携带情况,筛选CA-MRSA基因型菌株。采用金黄色葡萄球菌A蛋白（Staphylococcal protein A, SPA）基因分型、多位点序列分型（multilocus-sequence typing, MLST）等方法分析CA-MRSA菌株的分子水平特征;根据美国临床和实验室标准研究所（Clinical and Laboratory Standards Institute, CLSI）指南,采用纸片扩散法检测CA-MRSA菌株的药物敏感性,并对CA-MRSA菌株是否携带杀白细胞素基因（panton-valentine leukocidin gene, pvl基因）进行检测。结果:共收集到147株金黄色葡萄球菌,其中MRSA 58株,根据SCCmec分型结果,共有9株CA-MRSA,包括SCCmec Ⅳ 3株、SCCmecⅤ 6株。9株CA-MRSA菌株对多种非β-内酰胺类抗生素耐药,其中有8株对红霉素和克林霉素耐药,主要是由红霉素核糖体甲基化酶（erythromycin ribosomal methylase, erm）(B)基因介导;有8株对氨基糖苷类药物（主要为卡那霉素）耐药。对9株CA-MRSA菌株进行分子流行病学特征分析后发现,CA-MRSA主要以t437-ST59克隆为主,其他还有t034-ST804、t127-ST1、t008-ST8、t437-ST338等克隆;9株CA-MRSA菌株中,有5株携带毒力基因pvl。结论:致病性较强的CA-MRSA菌株逐渐进入医疗环境中,且对非β-内酰胺类药物的耐药性也逐渐增加,应加强对住院患者CA-MRSA分离株的监控。

关键词: 社区获得耐甲氧西林金黄色葡萄球菌, 分子特征, 耐药性

Abstract:

Objective: To investigate the molecular characterization and antimicrobial resistance of CA-MRSA(community-associated methicillin-resistant Staphylococcus aureus) strains isolated from clinical inpatientsto provide evidence for prevention and treatment of CA-MRSA infections. Methods: Isolates of S. aureus from hospitalized patients were collected within 24 h after admission from April 2014 to Dec. 2015, and mecA gene was detected to distinguish MRSA from MSSA (methicillin-sensitive Staphylococcus aureus). Genotypic CA-MRSA strains carrying SCC mec Ⅳ/Ⅴ were obtainedfor further analysis of molecular epidemiologic characters by spa-typing and MLST（multilocus -sequence typing）. Based on the CLSI (Clinical and Laboratory Standards Istitute) guidelines, disk diffusion method was used to test drug susceptibility of CA-MRSA strains. Moreover, the presence of pvl virulence gene was detected by PCR. Results: A total of 147 strains of S. aureus including 58 MRSA strains were collected from hospitalized patients. By SCCmec typing, 9 CA-MRSA strains (SCCmec Ⅳ 3; SCCmec Ⅴ 6) were detected. All CA-MRSA strains developed resistance against different non-β-lactams, among which 8 strains developed drug-resistanceagainst aminoglycosides (mainly kanamycin) and 8 strains developed drug-resistance against erythromycin and clindamycin mediated by erm(B) mainly. Molecular typing revealed that the main CA-MRSA clone was t437-ST59, and other clones were t034-ST804, t127-ST1, t008-ST8 and t437-ST338. In addition, 5 out of 9 CA-MRSA strains were pvl gene positive. Conclusions: More pathogenic CA-MRSA strains are invading healthcare-associated settings and developing more resistance against non-β-lactams, indicating that the CA-MRSA should be closely monitored in hospitals.

Key words: Community-associated methicillin resistant Staphylococcus aureus, Molecular characterization, Antimicro-bial resistance

中图分类号:

R515

王院霞, 姚锂凤, 郑巧平, 陈旭. 9株分离自住院患者的CA-MRSA基因型菌株的分子特征及耐药性研究[J]. 诊断学理论与实践, 2021, 20(01): 66-70.

WANG Yuanxia, YAO Lifeng, ZHENG Qiaoping, CHEN Xu. Molecular characterization and antimicrobial resistance of nine strains of CA-MRSA isolated from clinical inpatients[J]. Journal of Diagnostics Concepts & Practice, 2021, 20(01): 66-70.

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SCCmec类型	ccr基因复合物	mec基因复合物
Ⅰ	1	B
Ⅱ	2	A
Ⅲ	3	A
Ⅳ	2	B
Ⅴ	5	C2

引物名称	引物序列	基因片段（bp）
mecA-1	5′-TCCAGATTACAACTTCACCAGG-3′	162
mecA-2	5′-CCACTTCATATCTTGTAACG-3′
erm(A)-1	5′-GTTCAAGAACAATCAATACAGAG-3′	421
erm(A)-2	5′-GGATCAGGAAAAGGACATTT TAC-3′
erm(B)-1	5′-CCGTTTACGAAATTGGAACAGGTAAAGGGC-3′	359
erm(B)-2	5′-GAATCGAGACTTGAGTGTGC-3′
erm(C)-1	5′-GCTAATATTGTTTAAATCGTCAATTCC-3′	572
erm(C)-2	5′-GGATCAGGAAAAGGACATTTTAC-3′
pvl-1	5′-ATCATTAGGTAAAATGTCTGGACATGATCCA-3′	433
pvl-2	5′-GCATCAASTGTATTGGATACCAAAAGC-3′