Abstract
Abdominal actinomycosis is difficult to diagnose by endoscopy. A man in his thirties was presented to our hospital for evaluation of pain in the right lower abdominal quadrant and an abnormal C-reactive protein level on routine health checkup. Computed tomography revealed thickened walls of the rectum and sigmoid colon. On subsequent colonoscopy, the visibility of blood vessels was decreased and aphthous erosion was seen in the rectum and sigmoid colon. We considered the presence of infectious colitis and prescribed levofloxacin. However, his abdominal pain worsened, and he was admitted to our hospital two months later. A second colonoscopy showed that the sigmoid colon had narrowed due to edematous swelling. A mucosal tissue specimen was sent to the laboratory for culture, and Actinomyces israelii was detected. Abdominal actinomycosis was suspected, and the patient was treated with ampicillin. Abdominal actinomycosis may be suspected by mucous membrane culture of an endoscopic biopsy specimen and can be cured with antibiotics if administered in the early phase of the disease. Abdominal actinomycosis should always be included in the differential diagnoses of patients who present with nonspecific colitis, and a mucous membrane culture should be performed in such cases.
