Virulence Characteristics and Antibiotic Resistance Patterns among Various Phylogenetic Groups of Uropathogenic Escherichia coli Isolates.

The aim of this study was to determine the resistance patterns of uropathogenic Escherichia coli (UPEC) isolates and to investigate the frequency of several virulence genes, including fimH, papA, hlyD, cnf-1, sitA, and tsh, among various phylogenetic groups of UPEC isolates. A total of 85 E. coli isolates were recovered from urine samples from outpatients with a clinical diagnosis of uncomplicated urinary tract infections. A molecular approach to examine the antimicrobial resistance patterns was employed using PCR and the disc diffusion method. The detected frequencies of the virulence factor genes determined using PCR were: fimH (34.1%), papA (9.4%), hlyD (21.2%), cnf-1 (3.5%), sitA (15.3%), and tsh (27.1%). These results revealed that the isolates were resistant to trimethoprim-sulfamethoxazole (SXT) (74.1%), cefotaxime (CTX) (68.2%), and amoxicillin-clavulanic acid (AMC) (94.1%), and they were relatively less resistant to N (56.5%). According to these results, further investigation is needed to determine exactly whether or not SXT, CTX, and AMC are appropriate antibiotics for the treatment of UPEC infections in southern Iran. Although these results demonstrate that fimH is the most frequent virulence gene among UPEC isolates, the high prevalence of isolates that do not encode fimH (75.9%) and the relatively low frequency of isolates that carry other virulence genes require further investigation to clarify the role of the other potential virulence factors in the pathogenesis of these isolates.