2012 Volume 72 Issue 2 Pages 229-237
Human intestinal spirochetosis is a common condition in Western countries, but it is not well recognized in Japan. To determine the incidence and clinicopathologic findings of human intestinal spirochetosis in Japan, we performed a prospective study of a series of endoscopically resected biopsy specimens of the large intestine over a 4-month period at a single hospital located in Tokyo, Japan. Among 1025 samples, 42 cases of human intestinal spirochetosis were detected (4.1%). Genomic DNA from formalin-fixed paraffin-embedded biopsy specimen tissue samples was subjected to polymerase chain reaction analysis for the detection of two strains of spirochetes (Brachyspira aalborgi and Brachyspira pilosicoli) by amplifying species-specific portions of the NADH oxidase gene and 16S ribosomal RNA. B. aalborgi and B. pilosicoli were detected in 37 and 8 cases, respectively, with 5 cases having dual infection of both species. These results from a precise prospective study suggest that intestinal spirochetosis infection in Japan is not rare, and that the incidence is similar to that in Western countries. This finding differs from those of several retrospective studies that have claimed that the prevalence of intestinal spirochetosis is extremely low in Japan. In the current study, most cases of intestinal spirochetosis were asymptomatic, and the cases with digestive symptoms among the 1025 samples did not show any correlation with the status of intestinal spirochetosis infection. These results suggest that human intestinal spirochetosis infection is not pathogenic, but it is an incidental and/or indigenous infection that does not require treatment.
