在中国北京的临床和社区中发现的凝固酶阴性葡萄球菌具有极高的多样性和多种SCCmec元件。
Extreme diversity and multiple SCCmec elements in coagulase-negative Staphylococcus found in the Clinic and Community in Beijing, China.
作者信息
Chen Xiao-Ping, Li Wen-Ge, Zheng Hao, Du Hai-Yan, Zhang Li, Zhang Lei, Che Jie, Wu Yuan, Liu Shu-Mei, Lu Jin-Xing
机构信息
State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, 102206, China.
Microbiology Laboratory, Fu Xing Hospital, Capital Medical University, Beijing, 100038, China.
出版信息
Ann Clin Microbiol Antimicrob. 2017 Aug 22;16(1):57. doi: 10.1186/s12941-017-0231-z.
BACKGROUND
Coagulase-negative staphylococci (CoNS) are recognized as a large reservoir of staphylococcal cassette chromosome mec (SCCmec) harboured by Staphylococcus aureus. However, data of SCCmec in CoNS are relatively absent particularly in China.
METHODS
Seventy-eight CoNS clinical and 47 community isolates were collected in Beijing. PCR was performed to classify SCCmec types. Under oxacillin treatment, quantitative real-time reverse transcription PCR (qRT-PCR) was performed to compare mecA mRNA levels and mRNA half-life between isolates with single SCCmec element and those with multiple one. Their growth curves were analysed. Their bacterial cell wall integrity was also compared by performing a Gram stain. All ccr complex segments were sequenced and obtained ccr segments were analysed by phylogenetic analyses.
RESULTS
All 78 clinical isolates had mecA segments compared with 38% in community isolates (total 47). Only 29% clinical isolates and 33% community isolates (among mecA positive isolates) harboured a single previously identified SCCmec type; notably, 17% clinical isolates and 28% community isolates had multiple SCCmec types. Further studies indicated that isolates with multiple SCCmec elements had more stable mecA mRNA expression compared with isolates with single SCCmec elements. CoNS with multiple SCCmec elements demonstrated superior cell wall integrity. Interestingly, phylogenetic analyses of obtained 70 ccr segments indicated that horizontal gene transfer of the ccr complex might exist among various species of clinical CoNS, community CoNS and S. aureus.
CONCLUSIONS
CoNS recovered from patients carried extremely diverse but distinctive SCCmec elements compared with isolates from the community. More attention should be given to CoNS with multiple SCCmec not only because they had superior cell wall integrity, but also because CoNS and S. aureus might acquire multiple SCCmec through the ccr complex.
背景
凝固酶阴性葡萄球菌（CoNS）被认为是金黄色葡萄球菌携带的葡萄球菌盒式染色体mec（SCCmec）的一个巨大储存库。然而，CoNS中SCCmec的数据相对较少，尤其是在中国。
方法
在北京收集了78株CoNS临床分离株和47株社区分离株。采用聚合酶链反应（PCR）对SCCmec类型进行分类。在苯唑西林处理下，进行定量实时逆转录PCR（qRT-PCR），比较具有单个SCCmec元件的分离株与具有多个SCCmec元件的分离株之间的mecA mRNA水平和mRNA半衰期。分析它们的生长曲线。通过革兰氏染色比较它们的细菌细胞壁完整性。对所有ccr复合片段进行测序，并通过系统发育分析对获得的ccr片段进行分析。
结果
所有78株临床分离株均有mecA片段，而社区分离株（共47株）中这一比例为38%。只有29%的临床分离株和33%的社区分离株（在mecA阳性分离株中）携带单一先前鉴定的SCCmec类型；值得注意的是，17%的临床分离株和28%的社区分离株具有多种SCCmec类型。进一步研究表明，与具有单个SCCmec元件的分离株相比，具有多个SCCmec元件的分离株具有更稳定的mecA mRNA表达。具有多个SCCmec元件的CoNS表现出更好的细胞壁完整性。有趣的是，对获得的70个ccr片段的系统发育分析表明，ccr复合体的水平基因转移可能存在于临床CoNS、社区CoNS和金黄色葡萄球菌的不同物种之间。
结论
与社区分离株相比，从患者中分离出的CoNS携带极其多样但独特的SCCmec元件。应更多关注具有多个SCCmec的CoNS，这不仅是因为它们具有更好的细胞壁完整性，还因为CoNS和金黄色葡萄球菌可能通过ccr复合体获得多个SCCmec。
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