临床分离万古霉素耐药肠球菌van基因型及分子分型

van genotype and molecular typing of clinical isolates of vancomycin-resistant Enterococcus

目的明确临床分离万古霉素耐药肠球菌(VRE)基因型及分子分型。方法收集临床分离VRE 17株;采用16S r RNA测序对临床株进行菌种确认,微量稀释法和琼脂稀释法测定常用抗菌药物最低抑菌浓度(MIC)。多重PCR进行van基因分型;采用多位点序列分型(MLST)进行分子分型。结果 17株VRE经16S rRNA测序确认均为屎肠球菌;其中12株对替考拉宁耐药。13株检出vanA基因,9株检出vanM基因,5株同时检出vanA及van M基因;17株VRE分属6个MLST型,其中ST78型8株、ST80型4株、ST555型2株,其余3株分别为ST117型、ST262型和ST341型。结论 VRE的临床分离株中van基因型主要为vanA(76.5%),其次为vanM(52.9%),首次发现同时携带vanA及vanM的VRE菌株。

Objective To determine the genotype and molecular typing of vancomycin-resistant Enterococcus（VRE）. Methods Seventeen clinical isolates of VRE were collected in 2016. The strains were identified to species and confirmed by 16 S rRNA sequencing. The minimum inhibitory concentration of antimicrobial agents was determined by microdilution method and agar dilution method. Multilocus sequence typing（MLST） was used for molecular typing. Results The VRE strains were confirmed as Enterococcus faecium by 16 S rRNA sequencing. All strains were resistant to vancomycin, but only 12 strains were resistant to teicoplanin. The vanA gene was identified in 13 of the 17 strains. The vanM gene was detected in 9 strains. Both vanA and vanM genes were identified in five of the 17 strains. Six MLST types were identified in the 17 strains, including ST78（n=8）, ST80（n=4）, ST555（n=2）, and one each for ST117, ST262 and ST341. Conclusions The van genotype was primarily vanA（76.5%） and vanM（52.9%） in clinical isolates of VRE. The VRE strains carrying both vanA and vanM were found for the first time.