Urban Pigeons () as a Source of Broad-Spectrum β-Lactamase-Producing in Lisbon, Portugal.

Wild birds may be healthy carriers, and therefore, may be involved in the dissemination of clinically relevant antimicrobial-resistant bacteria, such as extended-spectrum β-lactamases (ESBL) and carbapenemase-producing . This study evaluated whether urban pigeons living in five spots in Lisbon, Portugal, may be colonized and, therefore, constitute potential spreaders of multidrug-resistant bacteria. A total of 100 pigeon fecal samples were collected in different urban areas for the detection of ESBL- or carbapenemase-producing . All β-lactamase-producing isolates were tested for antimicrobial susceptibility and their genetic backgrounds were characterized by multilocus sequence typing. Of the 100 fecal samples collected, nine ESBL-producing (9%) were identified. Three isolates carried the gene, three isolates harbored the and three isolates carried the gene. Genotyping of the nine ESBL-producing strains revealed seven different sequence types (STs) including ST10, ST131, ST154, ST206, ST1488 (SLV ST10), ST2858 and ST3576, most of which have been already described in humans, animals or in the environment. Urban pigeons constitute a potential source of ESBL genes and may be a transmission vehicle of multidrug-resistant bacteria in the environment.