AIM: To evaluate a multiplex PCR assay for the detection of bacterial and viral enteropathogens in stool samples from patients with ulcerative colitis(UC). METHODS: We prospectively analyzed 300 individuals, including immunocompetent patients, immunocompromised patients, and patients with UC. Stool samples were collected from the recto-sigmoid region of the colon by endoscopy. The samples were qualitatively analyzed for bacterial and viral enteropathogens with a multiplex PCR assay using a Seeplex® Kit. Additional clinical and laboratory data were collected from the medical records. RESULTS: A multiplex PCR assay detected 397 pathogens(191 bacteria and 206 viruses) in 215 samples(71.7%). The most frequently detected bacteria were Escherichia coli H7, 85(28.3%); followed by Aeromonas spp., 43(14.3%); and Clostridium perfringens, 36(12.0%) samples. The most prevalent viruses were Epstein-Barr virus(EBV), 90(30.0%); followed by human herpes virus-6(HHV-6), 53(17.7%); and cytomegalovirus(CMV), 37(12.3%) samples. The prevalence rate of CMV infection was significantly higher in the immunocompromised group than in the immunocompetent group(P < 0.01). CMV infection was more common in patients with UC(26/71; 36.6%)than in the immunocompetent patients excluding UC(6/188; 3.2%)(P < 0.01). CMV infection was more prevalent in UC active patients(25/58; 43.1%) than in UC inactive patients(1/13; 7.7%)(P < 0.05). Among 4 groups which defined by the UC activity and immunosuppressive drugs, the prevalence rate of CMV infection was highest in the UC active patients with immunosuppressive drugs(19/34; 55.8%). EpsteinBarr virus(EBV) infection was more common in the immunocompromised patients excluding UC(18/41; 43.9%) than in the immunocompetent patients excluding UC(47/188; 25.0%)(P < 0.05). The simultaneous presence of CMV and EBV and/or HHV6 in UC active patients(14/58; 24.1%) was greater than in immunocompromised patients excluding UC(5/41; 12.2%)(P < 0.05). CONCLUSION: The multiplex PCR assay that was used to analyze the stool samples in this study may serve as a non-invasive approach that can be used to exclude the possibility of CMV infection in patients with active UC who are treated with immunosuppressive therapy. AIM: To evaluate a multiplex PCR assay for the detection of bacterial and viral enteropathogens in stool samples from patients with ulcerative colitis (UC). METHODS: We prospectively analyzed 300 individuals, including immunocompetent patients, immunocompromised patients, and patients with UC. Stool samples were collected from the recto-sigmoid region of the colon by endoscopy. The samples were qualitatively analyzed for bacterial and viral enteropathogens with a multiplex PCR assay using a Seeplex® Kit. Additional clinical and laboratory data were collected from the medical records. RESULTS: A multiplex PCR assay detected 397 pathogens (191 bacteria and 206 viruses) in 215 samples (71.7%). The most frequently detected bacteria were Escherichia coli H7, 85 (28.3%); followed by Aeromonas spp., 43 (14.3%); and The most prevalent viruses were Epstein-Barr virus (EBV), 90 (30.0%); followed by human herpes virus-6 (HHV-6), 53 (17.7%); and cytomegalovirus ( CMV infection was more common in patients with UC (26/71; 36.6%) than in the immunocompromised group (P <0.01) ) than in the immunocompetent patients excluding UC (6/188; 3.2%) (P <0.01). CMV infection was more prevalent in UC active patients (25/58; 43.1%) than in UC inactive patients The prevalence rate of CMV infection was highest in the UC active patients with immunosuppressive drugs (19/34; 55.8%). Epstein Barr virus (EBV ) infection was more common in the immunocompromised patients excluding UC (18/41; 43.9%) than in the immunocompetent patients excluding UC (47/188; 25.0%) (P <0.05). The simultaneous presence of CMV and EBV and / or HHV6 in UC active patients (14/58; 24.1%) was greater than in immunocompromised patients excluding UC (5/41; 12.2%) (P <0.05). CONCLUSION: The multiplex PCR assay that was used to analyze the stool samples in this study may serve as a non-invasive approach that can be used to exclude the possibility of CMV infection in patients with active UC who are treated with immunosuppressive therapy.