A 74-year-old man was diagnosed with pulmonary tuberculosis via an abnormal chest X-ray and acid fast bacilli sputum smear (fig. 1). Antitubercular agents, including isoniazid (400 mg/day), rifampicin (600 mg/day), pyrazinamide (1,500 mg/day), and ethambutol (800 mg/day) were administered. Four months after initiation of antitubercular treatment, the patient complained of intermittent loose stool, tenesmus, and lower abdominal discomfort. Fifteen days later, his diarrhea became bloody and mucoid with a jelly-like appearance, and he suffered from aggravating lower abdominal discomfort. By the time the patient presented to our hospital, he was experiencing bloody diarrhea 5 to 6 times per day.
On physical examination, the patient was febrile, and his vital signs were within normal limits. His bowel movements were very frequent and his abdomen was soft and flat. Tenderness was noticed in the left lower quadrant of the abdomen without rebound tenderness. The patient's white blood cell count was 5,300/mm3, but serum C-reactive protein and erythrocyte segmentation rate were markedly elevated at 4.41 mg/dl and 57 mm/h, respectively. Sigmoidoscopy revealed multiple yellowish plaque lesions from the rectum to the sigmoid colon (fig. 2a), and mucosal biopsy from the sigmoid colon showed small collections of neutrophils between crypts at the summit of the mucosa with tufts of damaged surface epithelium (fig. 3).
The patient was diagnosed with PMC. We discontinued antitubercular agents and started oral metronidazole 250 mg twice per day with intravenous fluid and electrolytes. The patient's symptoms ameliorated slowly over 2 weeks of metronidazole treatment, during which he completely recovered from diarrhea, tenesmus, and abdominal pain. We restarted antitubercular agents, replacing rifampicin with levofloxacin. The patient experienced no recurrence of diarrhea by the end of antitubercular treatment, and his general condition recovered. Follow-up sigmoidoscopy did not show any evidence of PMC (fig. 2b).