Intestinal spirochetosis is defined as colonisation of the colon or appendix by the anaerobic spirochetes Brachyspira aalborgi or Brachyspira pilosicoli (first described in the 17th century by Antoni van Leeuwenhoek).1 Reported prevalence is 2-7% in Western countries, but rises to 54% in HIV-positive patients and those with homosexual contacts.2 There is controversy about whether these spirochetes are commensals or pathogens. However, invasion of colonic epithelium by spirochetes, in patients with anal receptive contacts induced through microtrauma, leads to destruction of microvilli. Patients may complain of abdominal pain, constipation, bloody stools or diarrhoea. Because spirochetes are very difficult to culture and usually no macroscopic abnormalities are seen in colonoscopy, the diagnosis is made by histological examination of colon biopsies. A ‘fuzzy’ line of spirochetes is seen at the epithelial surface. Immunostaining shows a cross-reaction with B. burgdorferi and Treponema pallidum. 3 Anti-microbial treatment can relieve symptoms by eliminating spirochetes, which leads to recovery of microvilli. Spontaneous recovery has also been described.4
Because our patient had debilitating symptoms, he was prescribed 500 mg metronidazole three times a day for one week, after which his symptoms completely resolved.
Credits go to Dr. Natté, pathologist, for providing the PA images.