Primary Study On The Mechanism Of Recurrent Urinary Tract Infection (UTIs) Caused By Uropathogenic Escherichia Coil (UPEC)

Objective: To investigate the Uropathogenic Escherichia coil(UPEC) mechanism to recurrent urinary tract infection(r UTI), molecule type, phylogenetic groups, virulence genes, antimicrobial susceptibility test and biofilm formation in vitro were compared between UPEC and intestinal commensal E.coli.Methods: 62 patients were collected from Shanghai No.6 hospital in January 2010 and December 2013,which was diagnosed UTI twice in 6 months.124 isolates of UPEC were obtained in all. According molecular typing,124 UPEC isolates were defined the relapse group(n=60)and the reinfection group(n=64).66 isolates of E.coli were obtained in intestinal tract from healthy people between January 2012 and December 2014.These strains were characterized for phylogenetic group, the carrying rate of different virulence factor, antibiotic resistance and in vitro biofilm formation.Results: In the relapse group, the major phylogenefic groups of UPEC were D(48.33%) and B2(30%).The carrying rates of feo B,chu A,iut A,iro N and ire A were 100%,85%,78.33%,61.67%and 13.33%.UPEC in the relapse group showed high resistance rates to ciprofloxacin(93.33%),ampicillin(90%),piperacillin(88.33%),cefazolin(86.67%),while low resistance rates to imipenem(0%),meropenem(0%)and fosfmycin(6.67%). The positive rate of Congo red test was 48.33%, while the positive rate of crystal violet test was 1.67%. In the reinfection group, the major phylogenefic groups of UPEC were D(54.69%) and B2(21.88%).The carrying rates of feo B,chu A,iut A,iro N and ire A were100%,71.88%,87.50%,60.94% and 12.50%. UPEC in the reinfection group showed high resistance rates to ampicillin(93.75%),piperacillin(93.75%),cefazolin(82.81%),while low resistance rates to piperacillin/tazobactam(6.25%),imipenem(0%) and meropenem(3.13%).The positive rate of Congo red test was 35.94%, while the positive rate of crystal violet test was1.56%.In the intestinal commensal, the major phylogenefic groups of E.coli were B1(37.88%)and D(31.82%).The carrying rates of feo B,chu A,iut A,iro N and ire A were100%,46.97%,53.03%,22.73% and 7.58%. E.coli in the intestinal commensal showed high resistance rates to ampicillin(60.6%),piperacillin(59.1%),while low resistance rates to amikacin(0%),piperacillin/tazobactam(3%),imipenem(1.5%),meropenem(0%),cefepime(12.1%)and fosfmycin(4.5%).The positive rate of Congo red test was 25.76%, while the positive rate of crystal violet test was 6.06%.Conclusions:The major phylogenefic groups of the relapse group UPEC and the reinfection group UPEC were B2 and D. The correspondant value in E.coli strains in intestinal tract was B1 and D. The differences virulence factors(chu A、feo B、iut A、iro N and ire A)between the two UPEC groups were very little. The carrying rate of the virulence factors(chu A、iut A、iro N) of UPEC in two groups were almost all higher than E.coil in intestinal commensal. UPEC in the relapse group showed high resistance rates to ciprofloxacin、ampicillin、piperacillin、cefazolin,while low resistance rates to imipenem、meropenem and fosfmycin. The correspondant value in the reinfection group was ampicillin 、 piperacillin 、 cefazolin, while low resistance rates to piperacillin/tazobactam,imipenem and meropenem. UPCE isolates demonstrated a remarkably higher resistance rates to most of the tested drugs than the intestinal commensal E.coil. Biofilm formation in vitro were no significant difference between the relapse group and the reinfection group.