背景:本研究调查了粪肠球菌中利奈唑胺和万古霉素敏感性的分布和特征(E.粪肠球菌)和屎肠球菌(E.faecium)并探索了潜在的抗性机制。
方法:回顾性收集2842株肠球菌临床分离株,并对其临床资料进行进一步分析。通过肉汤稀释法验证万古霉素和利奈唑胺的最低抑制浓度(MIC)。抗性基因optrA,cfr,vana,使用聚合酶链反应(PCR)研究vanB和vanM。通过全基因组测序(WGS)获得管家基因和抗性基因。
结果:在2842株肠球菌分离物中,88.5%(2516)来自尿液,其中屎肠球菌占60.1%。在27/28耐万古霉素肠球菌(VRE)分离株中鉴定出vanA基因,其中4个携带vanA和vanM基因。剩余的菌株为vanM阳性。在利奈唑胺抗性肠球菌(LRE)中的所有粪肠球菌分离物中鉴定了optrA基因。与粪肠球菌相比,粪肠球菌显示出更高的多重抗生素抗性指数(MAR指数)。多位点序列分型(MLST)显示屎肠球菌的序列类型主要属于克隆复合体(CC)17种,分析的近屎肠球菌分离株分为7种特征序列类型(STs),其中CC16的ST16是主要谱系。
结论:本研究中,尿液是VRE和LRE分离株的主要来源。与粪肠球菌相比,粪肠球菌表现出更高的抗性水平。在91.6%的LRE中检测到OptrA基因,这可以解释利奈唑胺耐药,在所有耐万古霉素肠球菌菌株中检测到van基因,而vanA是本研究确定的VRE的关键耐药机制。
BACKGROUND: This study investigates the distribution and characteristics of linezolid and
vancomycin susceptibilities among Enterococcus faecalis (E. faecalis) and Enterococcus faecium (E. faecium) and explores the underlying resistance mechanisms.
METHODS: A total of 2842 Enterococcus clinical isolates from patients were retrospectively collected, and their clinical data were further analyzed. The minimum inhibitory concentrations (MICs) of
vancomycin and linezolid were validated by broth dilution method. The resistance genes optrA, cfr, vanA, vanB and vanM were investigated using polymerase chain reaction (PCR). Housekeeping genes and resistance genes were obtianed through whole-genome sequencing (WGS).
RESULTS: Of the 2842 Enterococcus isolates, 88.5% (2516) originated from urine, with E. faecium accounted for 60.1% of these. The vanA gene was identified in 27/28
vancomycin resistant Enterococcus (VRE) isolates, 4 of which carried both vanA and vanM genes. The remaining strain was vanM positive. The optrA gene was identified in all E. faecalis isolates among linezolid resistant Enterococcus (LRE). E. faecium showed a higher multiple antibiotic resistance index (MAR index) compared to E. faecalis. The multi-locus sequence typing (MLST) showed the sequence type of E. faecium mainly belongs to clonal complex (CC) 17, nearly E. faecalis isolates analyzed were differentiated into 7 characteristics of sequence types (STs), among which ST16 of CC16 were the major lineage.
CONCLUSIONS: Urine was the primary source of VRE and LRE isolates in this study. E. faecium showed higher levels of resistance compared to E. faecalis. OptrA gene was detected in 91.6% of LRE, which could explain linezolid resistance, and van genes were detected in all
vancomycin resistant Enterococcus strains, while vanA was a key resistance mechanism in VRE identified in this study.