Virulence determinants and drug resistance mechanisms of two linezolid-intermediate Enterococcus faecalis isolates from bloodstream infection
10.3969/j.issn.1671-9638.2017.11.002
- VernacularTitle:2例利奈唑胺中介粪肠球菌血流感染的毒力及耐药机制
- Author:
Zhang-Ya PU
1
;
Guang-Jian XU
;
Wei-Ming YAO
;
Zhi-Jian YU
;
Zhong CHEN
;
Bing BAI
;
Xiang-Bin DENG
;
Xue-Ying HAN
;
Fo-Jun LIN
;
Bo ZHANG
;
Zhi-Chao XU
;
Qi-Wen DENG
Author Information
1. 广东医科大学附属深圳市南山区人民医院深圳市内源性感染诊治研究重点实验室
- Keywords:
linezolid;
Enterococcus faecalis;
bacteria;
resistance mechanism;
virulence gene
- From:
Chinese Journal of Infection Control
2017;16(11):999-1003
- CountryChina
- Language:Chinese
-
Abstract:
Objective To study virulence factors and drug resistance mechanism of linezolid-intermediate Enterococcus faecalis(E.faecalis) isolated from patients with bloodstream infection.Methods Two linezolid-intermediate E.faecalis strains,namely A and B,were isolated from two patients with bloodstream infection,the treatment of two patients was analyzed.The minimum inhibitory concentration (MIC) of linezolid and vancomycin were determined.The virulence genes (esp,asa1,gelE,ace,agg,efaA,cylA,and hyl) and linezolid resistance genes (domain V region of the 23SrRNA,cfr,cfr[B],optrA) were amplified by polymerase chain reaction (PCR).PCR products of domain V region of 23SrRNA gene were sequenced and analyzed.Results Symptoms of two patients who isolated two linezolid-intermediate E.faecalis strains were controlled after accepted linezolid therapy.Strains A and B were both susceptible to vancomycin(MICs were 1μg/mL and 4μg/mL respectively),teicoplain,ampicillin,and nitrofurantoin,while intermediate to linezolid(MIC were both 4μg/mL).Two strains both contained multiple virulence factors,strain A were negative for cylA and hyl,strain B were negative for hyl and esp,but positive for other virulence genes.There was G2621T mutation in domain V region of 23SrRNA in strain A,and no variation was found in strain B.Drug resistance genes of cfr,cfr(B),and optrA were all negative in both strain A and B.Conclusion In the present study,two linezolid-intermediate E.faecalis strains isolated from patients with bloodstream infection were susceptible to vancomycin and ampicillin,although the treatment of linezolid in two patients is effective,the utilization of linezolid therapy in clinical practice still needs to be cautious.The mutation of target site is a significant resistance mechanism,it is necessary for us to pay more attention to these clinical strains which are non-susceptible to such antimicrobial agents,and the treatment strategy needs further study.
