Rectal spirochaetosis in homosexual men: characterisation of the organism and pathophysiology.

Microbiological and electron microscopy studies were carried out on rectal biopsy specimens and faecal samples from eight practising male homosexuals and five heterosexual controls. Rectal spirochaetosis was present in five of the eight homosexual men. The organism was cultured and morphologically identified as a large anaerobic host associated treponeme. The degrees of infestation and depletion of microvilli were also measured. The results are discussed in relation to the possible clinical importance of rectal spirochaetosis.