Molecular analysis of virulence genes stx1, stx2, eaeA and hlyA in Escherichia coli isolated from cloacal samples in wild pigeons (Columba livia) and determination of their antibiotic resistance

Pigeons can be carriers for some human and animal pathogens, one of the most important of which is Escherichia coli.
This bacterium is responsible for outbreaks of many human diseases. Our objective was to determine the prevalence of Escherichia coli in cloacal area of pigeons in Tehran city (Iran), and determine the prevalence of some virulence genes and also antibiotics resistance pattern of isolates.
Altogether 117 samples of pigeon feces were collected from cloacal swab. The identification of bacteria was done by culture on differential culture media. Then antibiotic susceptibility test was performed by disk diffusion method. Isolates were tested for the presence of virulence genes stx1, stx2, eae and hlyA using multiplex polymerase chain reaction.
Escherichia coli were detected in 82.9% of 277 samples from pigeons. Sulfamethoxazole was the least effective drug (85.6% resistance), followed by tetracycline (83.5%). No resistance was detected to co-amoxiclav. The prevalence of stx1, stx2 and eaeA is 3.09%, 6.18% and 2.06% respectively and hlyA was not found in any of isolates.
The frequency of stx1 and stx2 distribution in animals and birds is not well understood as yet. Due to the close relationship of humans with birds like pigeons and presence of STEC strains in apparently healthy birds, necessitates considering precise regulations to restrict and prevent the prevalence of this life- threatening virus in Iran.