Occurrence and antibiotic sensitivity profile of thermophilic Campylobacter spp. isolated from soils associated with wild, captive and pet birds

Campylobacter spp. are among the leading causes of foodborne diarrhoeal diseases worldwide, posing a growing public health concern due to emerging antimicrobial resistance. This study investigated the occurrence and antibiotic resistance profile of Campylobacter spp. isolates in soil from bird (wild, captive and pet)-associated environments across three districts of Kerala (Thrissur, Kottayam, and Thiruvananthapuram). A total of 60 soil samples were collected from crop fields, nesting sites, zoo enclosures and pet bird cages. Conventional plating for Campylobacter spp. was performed using modified Charcoal Cefoperazone Deoxycholate agar, followed by biochemical and molecular confirmation through multiplex PCR. Physicochemical parameters (pH, electrical conductivity and organic carbon) were also analysed to evaluate their association with Campylobacter occurrence. Campylobacter spp. were detected in 8.3 per cent of 60 soil samples, with the highest occurrence in Thrissur (15 of 20 samples), followed by Kottayam (10 of 20 samples) and absent in Thiruvananthapuram. Campylobacter jejuni was the predominant species identified, while C. coli was detected in mixed infections. Soils positive for the organism exhibited slightly higher pH (5.9-6.7) and significantly lower electrical conductivity (11-70 uScm) compared to Campylobacter negative soils. Antibiotic susceptibility testing revealed that all the isolates remained sensitive to macrolides, fluoroquinolones, aminoglycosides and carbapenems. The MAR index ranged from 0.19 to 0.22, indicating moderate antibiotic exposure. These findings highlight soil as a potential environmental reservoir for Campylobacter, emphasising the need for routine soil-based surveillance and integrated One Health monitoring of antimicrobial resistance.