Brachyspira Species and Gastroenteritis in Humans

Brachyspira species have been implicated as a potential cause of gastroenteritis in humans; this is, however, controversial. In 733 gastroenteritis cases and 464 controls, we found 29 samples positive for Brachyspira species (2.3 % of cases and 2.6 % of controls; P 0.77). Brachyspira species were not associated with gastroenteritis in humans. Human intestinal spirochetosis (HIS) is caused by spirochetesfrom the genus Brachyspira (1) and is histologically charac-terized by the apical attachment of these bacteria to the mucosa of the colon (2). Three Brachyspira species have been reported to colonize humans: Brachyspira aalborgi, Brachyspira pilosicoli, and the provisionally named “Brachyspira hominis ” (3–7). Although it is unclear whether HIS is associated with clinical symptoms, there is evidence suggesting an association between B. pilosicoli and di-arrhea in humans (3, 8–11). However, due to the obligate anaer-obic culture requirements for these bacteria, most studies on HIS are based on histopathology without species differentiation, as histopathology requires additional techniques to differentiate be-tween species (3, 12). As a result, the clinical significance of HI