泌尿系感染患者大肠埃希菌fimH基因检测及尿便来源菌株同源性分析

目的：检测尿路致病性大肠埃希菌I型菌毛相关基因fimH携带率，调查相同泌尿系感染患者尿便大肠埃希菌的同源性，对相关基因fimH进行序列分析。方法：89株来自反复发作性尿路感染和急性单纯性膀胱炎患者清洁中段尿分离的大肠埃希菌。PCR方法检测I型菌毛基因fimH，采用Fisher确切概率法比较两组携带率是否有差异。取9名患者尿便同时培养的大肠埃希菌进行药敏初筛分型，同源性分析采用脉冲场凝胶电泳（PFGE）技术，对其fimH基因PCR扩增产物进行序列分析。结果：89株检出81株fimH阳性，两组检出率分别为（64／70）91．4％和（17／19）89．4％，P〉0．05。9名患者中5名患者尿便同时分离大肠埃希菌各自存在相同的PFGE型，同一患者尿便同型株中fimH阳性者序列比对无差异，不同型株fimH阳性者其序列均有6～7处变异。结论：fimH基因存在于绝大多数尿路致病性大肠埃希菌中。引起泌尿系感染的大肠埃希菌部分来源于肠道。

Examination of fimH gene of E.coli strains and the homology analysis of E.coli strains for patients with urinary tract infections

Objective： To examine carrying rate of uropathogenic Escherichia coli type I fimbriae, and investigate the homology of Escherichia coli for patient with urinary tract infections and analyze fimH gene sequence. Methods： A total of 89 Escherichia coli were acquired from patients with urinary tract infections and acute cystitis. Type I fimbriae fimH gene by PCR were detected. Fisher exact probability test were used to determine whether differences of carrying rates between the groups were significant. Escherichia coli were taken from urine and fecal of 9 patients and cultured at the same time. The early screening of the Escherichia coli were achieved by drug-sensitive test and homology analysis was carried out by pulsed-field gel electrophoresis （PFGE） technique. PCR amplification products offimH gene se- quence were also analyzed. Results： Among the 89 strains, eighty one were fimH-positive. Detection rates of the two groups were respective- ly （64/70） 91.4% and （17/19） 89.4%,（P〉0.05 ）. Escherichia coli of 5 patients out of nine with simultaneous separation from the urine and fecal revealed the same PFGE type and the fimH-positive strains of the same patient with the same PFGE type strain showed no difference in sequence alignments. Six to seven variations were found in the sequences of fimH-positive strains of the different PFGE type had. Conclu- sion： The results suggest that the fimH gene exists in most urinary tract pathogenic E.coli. And Escherichia coli causing urinary tract infection are partly from intestinal tract.