Abstract
We investigate the role of black-headed gulls (Chroicocephalus ridibundus), an omnivorous species that is among the most likely wild bird candidates for transmission of zoonotic agents, as a potential reservoir of Campylobacter spp. Colonies with different anthropogenic pressures were studied to examine differences in exposure to sources of Campylobacter between rural and urban birds. We recorded Campylobacter spp. in 4.87% of adult black-headed gulls and 2.22% of their chicks after analysing 1036 cloacal swabs collected over two breeding seasons in three colonies in northern Poland. Campylobacter jejuni was found most frequently (85.72%), and Campylobacter lari and Campylobacter coli were much scarcer. Prevalence of Campylobacter did not differ significantly between black-headed gulls breeding in urban (4.27%) and rural (3.80%) habitats. Almost all isolates from chicks and adults were susceptible to azithromycin (97.62%) and erythromycin (95.24%), but fewer to tetracycline (50.00%) and ciprofloxacin (47.62%). Campylobacter prevalence was unrelated to the date of sampling. Our study indicates that black-headed gulls are carriers of resistant to antibiotics Campylobacter and they can contaminate natural waterbodies with their faeces, which poses a threat to human and farm animal health.