Prevalance of thermophilic campylobacter species in settled (urban) wild birds and determination of antimicrobial profiles of isolates

This doctoral thesis aimed to determine the prevalence of thermophilic Campylobacter species in wild birds living alongside humans in Istanbul, to determine the species distribution of isolated strains, and to characterize their antimicrobial resistance profiles. In this study, 150 fresh fecal samples from wild birds living alongside humans (crows and seagulls living along the coastlines, and pigeons living in tourist areas in the city center) were collected by random sampling from various regions of Istanbul. For Campylobacter isolation, mCCDA agar was inoculated, and suspected isolates identified as Campylobacter spp by biochemical tests were identified by PCR. The phenotypic and genotypic antimicrobial susceptibility profiles of the isolated strains were determined. When fecal samples from wild birds living alongside humans in Istanbul were examined using conventional methods, Campylobacter spp. was isolated from 2/150 (1.33%). As a result of mPCR applied to DNAs obtained directly from the examination samples, 16 Campylobacter spp. were found in 15/150 (10%). 14 of these (93.3%) were identified as C. coli, and 2 (12.5%) were identified as C. jejuni. Campylobacter was detected in 11 of 127 pigeons (8.66%), while 10 (7.87%) were identified as C. coli, and 2 (1.57%) were identified as C. jejuni; campylobacter was detected in 4 of 22 seagulls (18.18%), and all were identified as C. coli. When the sample collection regions were compared, the frequency of Campylobacter spp was highest in Beyazıt Square (60%), followed by Küçükçekmece Beach (40%). As a result of antimicrobial susceptibility tests and PCR performed for the presence of tet(O), aphA-3 and gyrA genes, gyrA gene was found in both isolates, while tet(O) and aphA-3 genes were not detected. This thesis study revealed that wild bird populations resident in Istanbul are a significant reservoir for thermophilic campylobacter species and pose a potential public health risk. However, antimicrobial resistance was not detected in any of the isolates, indicating that campylobacter strains in these populations retain their susceptibility to existing antibiotics. These findings emphasize the importance of surveillance programs to reduce the risks of zoonotic transmission and monitor the spread of antimicrobial resistance. June 2025,