大肠埃希菌尿液分离株7种抗菌制剂外排泵基因研究

目的调查7种抗菌制剂外排泵基因(smr-2、emrB、emrD、emrE、mdf A、tehA、qacE△1)在大肠埃希菌尿液分离株中的存在情况。方法收集宁波市第一医院2008年10月～2009年3月患者尿液标本中分离的大肠埃希菌共28株,采用聚合酶链反应(PCR)及序列分析的方法分析7种外排泵基因。结果6种外排泵基因emrB、emrD、emrE、mdf A、tehA、qacE△1的阳性株数分别为26株(92.9%)、17株(60.7%)、21株(75.0%)、28株(100.0%)、27株(96.4%)、19株(67.9%),只有smr-2未能检出;且这6种外排泵基因以11种阳性模式存在,其中6种基因同时检出的模式:emrB+emrD+emrE+mdf A+tehA+qacE△1检出率最高,共9株(32.1%);另外,1号株mdf A和tehA的基因序列与美国NCBI中已登录的相关序列比对后,发现均为同义突变的新基因型。结论同时检测这7种抗菌制剂外排泵基因中6种基因在大肠埃希菌尿液分离株中被检测到,且阳性率很高,这或许是导致分离株呈多药耐药的一个重要原因。

Seven Drug Efflux Genes in Multi-drug Resistant Strains of Escherichia coli Isolated from Urine

OBJECTIVE To investigate the distribution of 7 drug efflux genes(smr-2,emrB,emrD,emrE,mdfA,tehA,and qacE△1)in multi-resistant strains of Escherichia coli isolated from urine.METHODS From Oct 2008 to Mar 2009,28 multi-resistant strains of E coli isolated from urine were collected from Ningbo No.1 Hospital,China.Seven drug efflux genes were analyzed by PCR and verified by DNA sequencing.RESULTS In 28 strains of E coli,26(92.9%),17(60.7%),21(75.0%),28(100.0%),27(96.4%),and 19(67.9%)isolates were detected to carry drug efflux genes emrB,emrD,emrE,mdfA,tehA,and qacE△1,respectively.However,smr2 couldn't be detected out.Furthermore,11 kinds of positive models were classified according to the presence of 6 drug efflux genes.Among them,9 strains(32.1%)carried emrB+emrD+emrE+mdfA+tehA+qacE△1(6 efflux genes detected).In addition,after genomic comparison with sequences registered in NCBI,fortunately,genotypes of mdfA and tehA carried on strain No.1 were confirmed as new subtypes(same-sense mutation),respectively.CONCLUSIONS It's the first report to detect 7 drug efflux genes simultaneously in China.Among them,6 drug efflux genes are detected and popular in strains of E.coli isolated from urine,which may be an important factor to induce multi-resistant strains.And it's the first report that emrB,emrD,and emrE are detected out in China,while the second report about mdfA in China.Moreover,genotypes of mdfA and tehA carry in strain No.1 is confirmed as new subtypes(same-sense mutation),respectively.