43株利奈唑胺耐药葡萄球菌耐药机制研究

Abstract

目的：了解我国耐利奈唑胺葡萄球菌的耐药形势，探讨耐利胺唑胺菌株的耐药形成机制，为临床合理使用抗生素提供理论依据。方法收集2009至2012年全国9家医院分离的所有非重复的利奈唑胺耐药葡萄球菌共43株。通过微量肉汤稀释法测其MIC值，PCR方法检测是否携带cfr基因以及是否发生23S rRNA基因Ⅴ区突变，Southern blot验证cfr基因是否在质粒上，质粒全基因组测序分析cfr基因周围环境。结果43株利奈唑胺耐药葡萄球菌大部分为多重耐药菌株，大部分菌株携带cfr基因和发生23S rRNA G2576T突变，cfr基因位于质粒上且其周围基因环境存在IS256或IS21－558插入序列、Tn558转座子可移动基因元件。结论获得cfr基因或23S rRNA G2576T突变是导致葡萄球菌对利奈唑胺耐药的主要机制，cfr基因位于质粒上，并且其周围存在可移动基因元件，可导致cfr基因在不同菌株或菌种间传播。（中华检验医学杂志，2016，39：848－851）

Objective To investigate the prevalence of linezolid-resistant Staphylococcus in China and analyze the resistance mechanism of linezolid-resistant isolates to provide the evidence of rational use of antibiotics.Methods Forty-three non-duplicate linezolid-resistant isolates were collected from 9 hospitals throughout China over a period of 4 years ( 2009 -2012 ) .The MIC of each antimicrobial agent was determined by the broth microdilution method .Presence of cfr and mutations in 23S rRNA were detected by PCR and sequencing .Presence of cfr in plasmid was determined by Southern blot .The genetic environment of the cfr was determined by whole plasmid genome sequencing and analysis .Results Most of the 43 linezolid-resistant Staphylococcus isolates showed a multidrug-resistant phenotype , and most of isolates harboured the cfr gene and mutation of 23S rRNA G2576T.Southern blott indicated that the cfr gene of these isolates resided on plasmids , which contained IS256 or IS21-558 insertion sequence and Tn558 transposon mobile genetic elements.Conclusions Acquired the cfr gene or the mutation of 23S rRNA G2576T in Staphylococcus can lead to the linezolid resistance .The cfr gene was located on the plasmid and surrounded by the mobile genetic elements , which could result in the spread of the cfr gene among the different isolates and species.