Intestinal spirochetosis and chronic watery diarrhea : Clinical and histological response to treatment and long-term follow up

Background: The clinical significance of intestinal spirochetosis is uncertain, therefore the aim of the present paper was to assess the prevalence of histological intestinal spirochetosis in patients with and without chronic watery diarrhea and to evaluate its clinical relevance. 
Methods: A prospective diagnostic work-up of intestinal spirochetosis was made on biopsy samples taken from patients with chronic watery diarrhea submitted between 1994 and 2004 (1174 colonoscopies with multiple biopsies). Three other positive cases identified from routine endoscopic biopsies also were reviewed. In addition, samples from 100 asymptomatic control patients and a random sample of another 104 colonic specimens were reviewed for intestinal spirochetosis. The diagnosis was established by light and electron microscopy. Polymerase chain reaction (PCR) amplification of the 16S ribosomal RNA and reduced nicotinamide adenine dinucleotide (NADH) oxidase genes of the intestinal spirochetes Brachyspira aalborgi and Brachyspira pilosicoli was performed on tissue biopsies of the 11 positive patients. After diagnosis, treatment with penicillin benzatine (PB) or metronidazole was offered to all symptomatic patients and they were followed for a mean of 45.4 months (range: 37-113 months). 
Results: Eight patients with chronic watery diarrhea were positive for intestinal spirochetosis. Intestinal spirochetosis was not diagnosed in the controls. Histological resolution of the infection paralleled clinical recovery in six patients (following metronidazole treatment in three). Most patients showed mild, non-specific colonic inflammation. Invasion by the spirochetes was not demonstrated by electron microscopy. Brachyspira aalborgi and B. pilosicoli each were identified by PCR in two cases. 
Conclusions: Histological intestinal spirochetosis appears to be relatively uncommon in Catalonia (Spain) compared to previous reports from other countries, but was identified in patients (0.7%) with chronic watery diarrhea. Sustained clinical recovery after spontaneous or drug-induced spirochetal disappearance in these individuals suggests that intestinal spirochetosis may play a pathogenic role in chronic watery diarrhea. Treatment with metronidazole is advisable in patients with persistent symptoms.