Phylogenetic characterisation, virulence factors, and multi-drug resistance of Escherichia coli strains isolated from faeces of feral pigeons (Columba Livia forma urbana).

BACKGROUND

Feral pigeons are a synanthropic species commonly found in cities worldwide. They are known to carry zoonotic pathogens, including Escherichia coli, and have long raised concerns about environmental contamination and public health risks.

OBJECTIVES

The aim of the study was to phylogenetically classify, identify selected virulence genes and determine the phenotypic antimicrobial susceptibility profiles of E. coli isolated from pigeon faeces in urban agglomeration.

METHODOLOGY

A total of 120 fresh faecal samples were collected from feral pigeons in urban areas. Groups of 4 samples from each location were tested in a total of 30 pools. A total of 97 faecal E. coli isolates were screened for enteropathogenic E. coli (EPEC) and Shiga toxin-producing E. coli (STEC) strain genes and thirteen selected virulence factors associated with pathogenic function and activity. Resistance patterns were determined by the Kirby-Bauer disk diffusion method for twenty antibiotics.

RESULT

The most common phylogenetic group was group D (70/97, 72.2%), followed by group A (15/97, 15.5%), B1 (7/97, 7.2%) and B2 (3/97, 3.1%). EPEC and STEC were found in 5.2% and 22.7% isolates, respectively. The obtained results showed katP, lpfA, tir, iha and lpfA genes in eaeA-positive and stx-positive isolates, mainly from phylogroups D and B2. The isolated E. coli strains were resistant to at least one antibiotic in 16.5%, and 2.1% were recognised as multidrug-resistant (MDR).

CONCLUSIONS

The results of this study confirm that pigeons in the urban environment are carriers of potentially pathogenic strains of E. coli, including MDR strains. Twelve patterns of virulence genes were identified among E. coli strains, with a great predominance of the single gene stx encoding Shiga toxin 1. The highest resistance was observed for imipenem (IMP), tetracycline (TE) and doxycycline (DO), respectively, and these antibiotics were also involved in most of the observed resistance patterns. The obtained results justify the implementation of preventive measures in cities and the introduction of surveillance programs for synanthropic pigeon populations to protect both the urban environment and public health.