Background: Spirochaetes are well known causative agents of diarrhoea in veterinary medicine. However, there is no agreement as to whether or not they have any clinical significance in humans.

Aims: To assess the symptoms associated with intestinal spirochaetosis, their response to treatment and the natural history of untreated cases.

Methods: A retrospective review of all cases of intestinal spirochaetosis identified within an eight year period in a single university teaching hospital was performed. A chart review and follow up telephone interview was performed to assess the indications for colonoscopy that led to the diagnosis, treatment received, and duration and nature of symptoms.

Results: 18 cases were identified. The indications for colonoscopy were diarrhoea in 50% and rectal bleeding in 16.7%; also investigation of constipation, anaemia and abdominal pain, and in two cases reassessment of chronic proctitis. Two subjects were treated with metronidazole and two were treated with aminosalicylates. 69% had complete resolution of symptoms at follow-up, 15% had persistent symptoms and 15% had intermittent symptoms. Of the two patients treated with metronidazole, one had resolution of symptoms and one has persistent abdominal pain.

Conclusion: Symptoms do not appear to parallel spirochaete persistence or eradication and therefore it seems appropriate to adopt a wait and see approach to treatment of patients in whom spirochaetes are identified, giving a trial of antimicrobial treatment only in those who have severe or persistent symptoms. Careful consideration of both host and pathogen should be undertaken.