Background and aimsThe role of bacterial infection in the pathogenesis of ulcerative colitis (UC) is under investigation. This study aims to (i) determine the prevalence of Campylobacter spp. and Arcobacter spp. in patients with UC, (ii) identify the antibiotic susceptibility of isolated agents, and (iii) investigate the role of these microorganisms in the pathogenesis and/or activation of UC.Patients and methodsEighty patients with UC and 40 healthy individuals were included in the study. Stool samples were used for cultural examination. Direct plating, membrane filtration, and enrichment methods were used for isolation. 16s rRNA sequence analysis was used for definitive identification of isolates that were identified phenotypically.ResultsIn the UC group, 20 (25%) patients had proctitis, 40 (50%) patients had left-type involvement, and 20 (25%) patients had extensive involvement. Campylobacter spp. were isolated from four (5%) patients in the UC group and isolates were identified as C. curvus, C. concisus, C. sputorum, and C. jejuni. C. concisus and C. jejuni were found to be resistant to ciprofloxacin, levofloxacin, and trimethoprim-sulfamethoxazole. C. jejuni was also resistant to tetracycline. All samples were negative for Arcobacter spp. The samples from the control group neither showed the presence of Campylobacter spp. nor Arcobacter spp.ConclusionGiven the clinical, endoscopic, and bacteriological examination results, it is believed that Campylobacter spp. are agents that cause flare-up clinically by being superimposed on the primary disease, rather than agents that initiate the disease in patients with UC. Arcobacter spp., which are known to cause acute gastroenteritis, were not found to be associated with UC.