Antibiotic resistance profile and virulence genes of uropathogenic Escherichia coli isolates in relation to phylogeny

摘要

Escherichia coli (E. coli) strains are the major cause of urinary tract infections(UTI) and belong to the large group of extra-intestinal pathogenic E. coli. The purposes of thisstudy were to determine the antibiotic resistance profile, virulence genes and phylogeneticbackground of E. coli isolates from UTI cases. A total of 137 E. coli isolates were obtainedfrom UTI samples. The antimicrobial susceptibility of confirmed isolates was determined bydisk diffusion method against eight antibiotics. The isolates were examined to determine thepresence and prevalence of selected virulence genes including iucD, sfa/focDE, papEF andhly. ECOR phylo-groups of isolates were determined by detection of yjaA and chuA genes andfragment TspE4.C2. The antibiogram results showed that 71% of the isolates were resistant tocefazolin, 60.42% to co-trimoxazole, 54.16% to nalidixic acid, 36.45% to gentamicin, 29.18% tociprofloxacin, 14.58% to cefepime, 6.25% to nitrofurantoin and 0.00% to imipenem. Twentytwoantibiotic resistance patterns were observed among the isolates. Virulence genotypingof isolates revealed that 58.39% isolates had at least one of the four virulence genes. TheiucD gene was the most prevalent gene (43.06%). The other genes including sfa/focDE,papEF and hly genes were detected in 35.76%, 18.97% and 2.18% isolates, respectively. Ninecombination patterns of the virulence genes were detected in isolates. Phylotyping of 137isolates revealed that the isolates fell into A (45.99%), B1 (13.14%), B2 (19.71%) and D(21.16%) groups. Phylotyping of multidrug resistant isolates indicated that these isolates aremostly in A (60.34%) and D (20.38%) groups. In conclusion, the isolates that possessed theiucD, sfa/focDE, papEF and hly virulence genes mostly belonged to A and B2 groups, whereasantibiotic resistant isolates were in groups A and D. Escherichia coli strains carrying virulencefactors and antibiotic resistance are distributed in specific phylogenetic background.