Infective colitis associated with human intestinal spirochetosis

Aim: Our study reports the detection and identification of intestinal spirochetosis in patients with colonic diseases in a tertiary-care hospital over a 12-year period, and includes a description of all cases we diagnosed. Methods: Our patients (8323) underwent colonoscopy and histopathological examinations including transmission electron microscopy (TEM) and light microscopy. Specimens from patients suspected of intestinal spirochetosis at histopathology (17 patients) underwent microbiological investigation performed by culture and molecular methods (16S restriction fragment length polymorphism-polymerase chain reaction [RFLP-PCR], nox RFLP-PCR assays). Results: Seventeen cases were diagnosed: seven patients were infected by B. aalborgi, one by B. pilosicoli, two by both species and four by Brachyspira spp. diagnosed both histopathology and microbiology (culture and molecular methods: 16S RFLP-PCR and nox RFLP-PCR assays). Three cases were referred to as Brachyspira spp. infections using only histopathology, including TEM. Conclusions: Our results demonstrated that intestinal spirochetosis, although rarely occurring, might play a role in chronic diarrhea and suggested a pathogenetic mechanism of intestinal spirochetosis based on the destruction of colonic microvilli and colitis histologically documented, providing additional clinical and pathological information on this entity. This study suggests that metronidazole seems to be the drug of choice for the eradication of intestinal spirochetosis.