Abstract
BACKGROUND: Clostridioides difficile (C. difficile) colitis is one of the most common infections in hospitalized patients, characterized by fever and diarrhea. It usually improves after appropriate antibiotic treatment; if not, comorbidities should be considered. Cytomegalovirus (CMV) colitis is a possible co-existing diagnosis in patients with C. difficile infection with poor treatment response. However, compared with immunocompromised patients, CMV colitis in immunocompetent patients is not well studied. CASE SUMMARY: We present an unusual case of co-existing CMV colitis in an immunocompetent patient with C. difficile infection. An 80-year-old female patient was referred to the infectious disease department due to diarrhea, abdominal discomfort, and fever for 1 wk during her hospitalization for surgery. C. difficile toxin B polymerase chain reaction on stool samples was positive. After C. difficile infection was diagnosed, oral vancomycin treatment was administered. Her symptoms including diarrhea, fever and abdominal discomfort improved for ten days. Unfortunately, the symptoms worsened again with bloody diarrhea and fever. Therefore, a sigmoidoscopy was performed for evaluation, showing a longitudinal ulcer on the sigmoid colon. Endoscopic biopsy confirmed CMV colitis, and the clinical symptoms improved after using ganciclovir. CONCLUSION: Co-existing CMV colitis should be considered in patients with aggravated C. difficile infection on appropriate treatment, even in immunocompetent hosts.