Abstract

Objective: To detect several virulence genes among Escherichia coli (E. coli) isolates of serogroup O1 collected in Tehran, Iran. Methods: In this study, 100 clinical isolates of E. coli were collected in Tehran, Iran. The antibiotic susceptibility test was done for 14 antibiotics according to CLSI guidelines. Phylogenetic grouping was performed by PCR according to the chuA, yjaA and TspE4.C2 genes. Serogroup typing was performed using the 12 O-antigens. The virulence genes were detected by PCR. Results: A total of 37 isolates belonged to serogroup O1. All of E. coli isolates were sensitive to phosphomycin. Phylogroups A (30%), B1 (21%), B2 (39%), and D (10%) were detected. The prevalence rates of cnf, cdt, iutA, csgA, kpsMII, ibeA, vat, traT, TcpC, sat, hlyA and pic were 19%, 8%, 78%, 84%, 43%, 8%, 16%, 81%, 0%, 38%, 92% and 8%, respectively. Also, the vat gene was the most dominant gene in A phylogroup, and the genes of sat and pic were the most dominant virulence genes in the B2 phylogroup. Conclusions: The phosphomycin, imipenem, and meropenem were the most effective antibiotics. Half of the isolates were multidrug resistant. The predominant virulence factors of E. coli isolates were the genes hlyA, iutA, traT, and csgA. Detection of virulent strains which exhibit wide antibiotic resistance can help the control programs in order to prevent the spread of infections. According to the results, the B2 phylogroup was the most common phylogroup and strains belonging to B1 phylogroup were the most resistant strains in O1 serogroup E. coli strains.

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