万古霉素依赖性屎肠球菌的生物学特性观察

摘要

Objective To observe the biological characteristics of a vancomycin-dependent enterococcus faecium (VDEfm-1501).Methods A strain of VDEfm-1501 was isolated from an urine specimen of a woman with blood system disease and was identified by VITEK 2,followed by PCR and VITEK MS.The VDEfm-1501 vancomycin-dependent growth characteristics and the minimum vancomycin concentration required for growth were tested by E-test.Its antibiotic resist-ance was analyzed by K-B disc diffusion.Drug resistance and virulence genes were amplified by PCR.The multilocus se-quence typing (MLST)was applied in the sequence typing.Ddl sequencing of VDEfm-1501 was detected by PCR.Results VDEfm-1501 could only grow on the presence of 1.0 μg/mL vancomycin at least,but such characteristic could weaken with the increase of passage times,and no vancomycin-dependence was found in the sixth passage.VDEfm-1501 showed multi-drug resistance except linezolid and tetracycline,and carried resistant gene of ace(6')-Ie-aph(2")-la.VDEfm-1501 belonged to clonal complex 17 (CC17),which was the cause of most of the nosocomial VRE outbreaks globally.And its vancomycin dependence seemed to be associated with the insertion of 'GG'at nucleotide position 942 of the ddl gene.Con-clusions The growth of VDEfm-1501 needs at least 1 μg/mL vancomycin,but such dependence is easy to lose.VDEfm-1501 displays multi-drug resistance and carrys the resistant gene of ace(6')-Ie-aph(2")-la.VDEfm-1501 belongs to ST of VRE.The insertion of 'GG'leads to the emergence of VDEfm-1501.%目的：观察万古霉素依赖性屎肠球菌（VDEfm-1501）的生物学特性。方法1株从1例血液病患者尿液中分离到的依赖万古霉素生长的 VDEfm-1501，先用 VITEK 2细菌鉴定仪对其进行菌种鉴定，之后用 PCR 法和VITEK MS 质谱鉴定法对其进一步验证。E-test 法检测 VDEfm-1501万古霉素依赖生长特性及生长所需的最低万古霉素浓度；K-B 法检测 VDEfm-1501耐药性；PCR 法检测 VDEfm-1501耐药基因；多位点序列分型法对 VDEfm-1501进行序列型（ST）分型；PCR 法对 VDEfm-1501的 D-丙氨酸连接酶基因（ddl 基因）进行测序。结果随着VDEfm-1501传代次数增多其万古依赖性逐渐减弱，传至第5代时这种依赖性不再明显，第6代时几乎完全消失；VDEfm-1501正常生长至少需要1．0μg／mL 的万古霉素。VDEfm-1501对氨苄青霉素、庆大霉素及环丙沙星耐药，仅对利奈唑胺和四环素敏感；VDEfm-1501携带庆大霉素耐药基因[ace（6′）-Ie-aph（2″）-la 基因]。VDEfm-1501为耐万古霉素的肠球菌（VRE）ST 型，属于 CC17克隆复合体。VDEfm-1501的 ddl 基因942 bps 位置上插入了“GG”。结论 VDEfm-1501依赖万古霉素生长的特性容易丢失，其生长所需的最低万古霉素浓度为1．0μg／mL。VDEfm-1501多重耐药，携带耐药基因 ace（6′）-Ie-aph（2＂）-la 基因。VDEfm-1501属于 VRE 的 ST 型。ddl 基因942 bps 位置上“GG”的插入导致了 VDEfm-1501的出现。