Genotypic and Phenotypic Characterization of Pathogenic , spp., and spp., in Free-Living Birds in Mainland Portugal.

Birds are potential carriers of pathogens affecting humans and agriculture. Aiming to evaluate the occurrence of the top three most important foodborne pathogens in free-living birds in Portugal, we investigated 108 individual fecal samples from free-living birds and one pooled sample of gull feces ( = 50) for the presence of (pathogenic and non-pathogenic), spp. and spp. Virulence- and antimicrobial resistance- (AMR) associated genes were detected by PCR and Whole-Genome Sequencing (WGS), and phenotypic (serotyping and AMR profiles) characterization was performed. Overall, 8.9% of samples tested positive for pathogenic , 2.8% for spp., and 9.9% for spp. AMR was performed on all pathogenic isolates and in a fraction of non-pathogenic , being detected in 25.9% of them. Ten of the tested isolates were multidrug-resistant (MDR), and seven of them were Extended-spectrum β-lactamase (ESBL) producers. Among ( = 3) and ( = 9), only one strain of was identified as MDR. Most of the identified serotypes/sequence types had already been found to be associated with human disease. These results show that free-living birds in Portugal may act as carriers of foodborne pathogens linked to human disease, some of them resistant to critically important antimicrobials.