Clonal groups of extended-spectrum beta-lactamase and biofilm producing uropathogenic Escherichia coli in Iran

Pathogenicity of a bacterium is affected by the social characteristics of the population and environmental factors. The ability of biofilm formation among beta-lactamase-producing uropathogenic Escherichia coli (UPEC) could facilitate the exchange of antibiotic-resistance genes, which resulted in widespread dissemination of antibacterial drug resistance. We investigated the prevalence of biofilm and beta-lactamase producing UPECs among patients with urinary tract infection (UTI) in two cities with different demographics and climates in Iran. A total of 265 E. coli was isolated from patients with UTIs from two referral hospitals (n = 191) and two outpatient clinics (n = 74) in Isfahan and Zahedan, Iran. Production of curli and cellulose, and, biofilm formation was investigated using Congo red agar and microtiter plate methods, respectively. Biofilm producing (BFP) isolates (n = 107) were further characterized using rep-PCR, antimicrobial susceptibility testing and extended-spectrum beta-lactamase (ESBL)/AmpC phenotypic production. Isolates were also screened for the presence of carbapenemase, ESBL and AmpC genes using multiplex PCR. High diversity was found among BFP strains in both cities, with 58% strains producing ESBL and 21% producing AmpC. ESBL (98%), AmpC (50%) and carbapenemase genes (40%) were identified in BFP strains with ESBL-positive phenotype, respectively. The prevalence of BFP strains, antibiotic resistance and beta-lactamase genes in Zahedan, a low socioeconomic city with a warm climate, was significantly higher than that of Isfahan. High prevalence of biofilm and beta-lactamase producing UPEC strains among strains from Zahedan suggests that socioeconomic status and environmental factors might have a role in pathogenicity of the strains.