CTX-M-producing Escherichia coli Isolated from urban pigeons (Columba livia domestica) in Brazil.

Introduction: Worldwide urban pigeons (Columba livia domestica) are an important reservoir of pathogenic and multidrug-resistant bacteria (MDR). Plasmids are key genetic elements in the dissemination of antimicrobial drug resistance in bacteria, including beta-lactams and quinolones, which are the most important classes of drugs for treatment of Enterobacteriaceae infections in human and veterinary medicine. The aim of this study was to determine the presence of Escherichia coli (E. coli) harboring plasmids containing extend-spectrum (ESBL) and pAmpC beta-lactamases, also plasmid-mediated quinolone resistance (PMQR) genes in urban pigeons from São Paulo State, Brazil.

Methodology: A collection of 107 isolates of E. coli from urban pigeons from four cities was screened by antimicrobial resistance phenotypic and PCR for genes encoding ESBL, pAmpC and PMQR genes. Clonality was evaluated by ERIC-PCR.

Results: We found three strains positive for blaCTX-M genes. In two clonally related CTX-M-8-producing strains, the gene was associated with IncI1 plasmids. An MDR strain harboring blaCTX-M-2, the plasmid could not be transferred. No strain was positive for PMQR genes.

Conclusion: These results indicate that CTX-M-2 and CTX-M-8-producing E. coli are present in urban pigeons, which could serve as a reservoir for ESBL-producing E. coli in Brazil.