β-内酰胺耐药粪肠球菌的低亲和力青霉素结合蛋白检测与多位点序列分型

Detection and multi-locus sequence typing of low-affinity penicillin-binding protein of β-lactam resistant Enterococcus faecalis

目的检测临床分离粪肠球菌的耐药性、低亲和力青霉素结合蛋白pbp4基因和多位点序列分型(MLST)情况。方法收集临床分离的粪肠球菌78株,使用自动化仪器检测其耐药性;采用PCR扩增及基因测序的方法检测TEM基因和pbp4基因突变的突变情况;应用MLST对分离菌株进行进行多位点序列(MLST)分型。结果78株粪肠球菌对环丙沙星、左氧氟沙星、利福平、红霉素、四环素以及高浓度庆大霉素的耐药率较高,对青霉素和氨苄青霉素的耐药率为10.3%,未发现对呋喃妥因、万古霉素、替考拉宁和利奈唑胺耐药的菌株;78株粪肠球菌中有8株扩增出TEM基因,全部对青霉素和氨苄青霉素耐药,阳性率为10.3%;78株粪肠球菌共分为16个序列型,其中ST179型和ST16型最多,分别有21株和20株,占26.9%和25.6%,其余依次为ST6型8株(10.3%),ST4型7株(9.0%),ST585型6株(7.7%),ST480型4株(5.1%),ST28型3株(3.8%),其余各ST型只检出1株;分析ST型别与耐药性的关系显示相同ST型别的粪肠球菌具有类似的耐药谱。结论粪肠球菌对β-内酰胺类抗菌药物的耐药机制主要是由于产生由TEM基因介导的β-内酰胺酶所致,与pbp4基因的突变没有必然联系;粪肠球菌分离菌株主要以CC16(包含ST16和ST179)克隆株为主且耐药情况严重,需要针对其特点指导临床用药并加强院内感染监控。

Objective To detect the low-affinity penicillin-binding protein drug resistance,pbp4 gene,and multi-locus sequence typing(MLST)of clinically isolated E.faecalis.Methods 78 clinical isolates of E.faecalis were collected,and their drug resistance was detected by automated instruments;the mutation of pbp4 gene mutation was analyzed by PCR amplification and MLST.Results 78 strains of E.faecalis were highly resistant to ciprofloxacin,levofloxacin,rifampicin,erythromycin,tetracycline and high concentration of gentamicin,and were resistant to penicillin and gentamicin.The ampicillin resistance rate was 10.3%,and no strains were found to be resistant to nitrofurantoin,vancomycin,teicoplanin and linezolid;8 strains of 78 E.faecalis had amplified TEM genes,and all of them were resistant to penicillin and ampicillin resistance,with a positive rate of 10.3%;the allelic profiles and sequence types of 78 strains of E.faecalis which were divided into 16 sequence types,of which ST179 and ST16 were the most,with 21 and 21 strains,respectively.20 strains,accounting for 26.9%and 25.6%,the rest were ST6 type 8 strains(10.3%),ST4 type 7 strains(9.0%),ST585 type 6 strains(7.7%),ST480 type 4 strains(5.1%),ST28 strains 3 strains(3.8%)of the ST type were detected,and only 1 strain was detected for the other ST types.The analysis of the relationship between ST types and drug resistance showed that E.faecalis with the same ST type had similar drug resistance profiles.Conclusion The resistance mechanism of E.faecalis toβ-lactam antibiotics is mainly caused by the production ofβ-lactamase mediated by TEM gene,which is not necessarily related to the mutation of pbp4 gene.The isolates of E.faecalis are mainly CC16(including ST16 and ST179)clones and drug resistance is serious.It is necessary to guide clinical medication and strengthen nosocomial infection monitoring according to its characteristics.