Identification of Terminal βGlcNAc on Brachyspira Species in Human Intestinal Spirochetosis

Human intestinal spirochetosis (HIS) is a colorectal bacterial infection caused by the Brachyspira species. Griffonia simplicifolia-II (GS-II) is a lectin specific to terminal α/βGlcNAc residues. Here, we investigated terminal βGlcNAc residues in the context of HIS infection using GS-II-horseradish peroxidase staining and HIK1083 immunostaining specific to terminal αGlcNAc residues. Fourteen of 15 HIS cases were GS-II-positive on the bacterial body. No cases showed HIK1083 positivity. The percentage of bacterial bodies staining positively for GS-II based on comparison with anti-Treponema immunostaining was ≤30% in seven cases, 30-70% in two, and >70% in six. Of 15 HIS cases analyzed, none were comorbid with tubular adenomas, and three were comorbid with sessile serrated lesions (SSLs). To determine the species of spirochete infected, the B. aalborgi-specific or B. pilosicoli-specific NADPH oxidase genes were amplified by PCR. After direct sequencing of the PCR products, all nine cases in which PCR products were observed were found to be infected with B. aalborgi alone. These results indicate that the HIS bacterial body, especially of B. aalborgi, is characterized by terminal βGlcNAc and also indicate that terminal βGlcNAc on the HIS bacterial body is associated with HIS preference for SSLs.