Effect of fimH gene on type 1 fimbriae adhesion of uropathogenic Escherichia coli: a preliminary study / 中华临床感染病杂志

ABSTRACT

Objective To investigate the effect of fimH gene on type 1 fimbriae adhesion of uropathogenic Escherichia coli (UPEC) and the gene variations between type 1 fimbriae adhesion positive and negative bacteria.Methods A total of 171 UPEC strains (not catheter associated) were collected from the Second Hospital of Tianjin Medical University,Tianjin First Center Hospital,and Tianjin Children's Hospital during January 2012 and January 2013.fimH gene was detected by PCR technique,and type 1 fimbriae adhesion was detected by yeast agglutination test.RT-PCR was used to exterminate gene transcript factor impacting on adhesion.Chi-square and Yates' chi-squared tests were performed to comparefimH gene sequences between the adhesion positive and negative bacteria.Results Among 171 UPEC strains,142 (83％) werefimH gene positive,and type 1 fimbriae was expressed in 98 strains (57％).All adhesion positive strains carriedfimH gene.Among 44 strains with positivefimH gene and negative adhesion RT-PCR revealed thatfimH gene did not transcript in 8 strains (18％).The sequencing results showed that gene mutation on the 51 st amino acid site was more prevalent in the adhesion positive group compared with the negative group (x2 =6.64,P =0.010).In adhesion,mutations on the 190th and 219th amino acid sites were observed in 6 strains and 7 strains of negative group,respectively; while not observed in the adhesion positive group (x2 =4.69 and 5.87,P ＜ 0.05).Negative adhesion in other 23 strains was not attributed to single nucleotide polymorphism.Conclusion Adhesion function of type 1 fimbriae mignt be affected by mutation and deletion offimH gene.Three key site mutations may also affect the adhesion function of type 1 fimbriae.Besides fimH gene,there may be other genes that can affect the adhesion function of type 1 fimbriae.