Free-Living Birds as Reservoirs of Enterococcus spp.: A Potential Environmental Health Concern

This study investigated the occurrence of Enterococcus species, known for their worrying antibiotic resistance profiles, in free-living birds, due to their role as potential reservoirs of these bacteria. Cloacal swabs were collected from 94 wild birds, including Eurasian blackcap, blackbird, house sparrow, and common kingfisher, captured around urban streams in Coimbra, Portugal. Faecal samples from birds in Benevento, Italy, and Ghent, Belgium, were also analysed. After isolation, bacteria were identified using MALDI-TOF MS. Enterococcus faecalis was the predominant species across all bird species sampled in Coimbra, with high occurrence in common kingfishers (66.7%), house sparrows (31.6%), blackbirds (19.4%), and Eurasian blackcaps (16.7%). Enterococcus faeciumwas found only in house sparrows (26.3%) and blackbirds (5.6%) in Coimbra. E. faecalis was also detected in faecal samples from Benevento and Ghent in blackbirds, house sparrows, and common kingfishers, while E. Faecium was not isolated from samples of these two geographical areas. The findings obtained confirm the presence of E. faecalis and E. faecium in avian fauna inhabiting aquatic environments. The occurrence in aquatic birds like the common kingfisher highlights the potential link between water quality, biodiversity, and the spread of opportunistic pathogens, emphasising the importance of a One Health approach.