Identification of group C Streptococcus with Helix pomatia lectin in use for blood grouping

The lectin anti-AHP (Helix lectin) obtained from the albumen gland of an edible snail, Helix pomatia, was used for the identification of group C streptococci. All 1, 045 strains of group C streptococci (S. equisimilis, S. zooepidemicus, and S. dysgalactiae) were agglutinated with the Helix lectin, but none of the 12, 264 strains of group A, 1, 346 strains of group G, 330 strains of group B, and 121 strains of other streptococcal groups was not. A few strains of S. equisimilis which belongs to group C have on the cell surface specific T antigen of group A streptococci, but it did not affect the agglutination with Helix lectin. Some strains of S. milleri carrying or not carrying group G specific carbohydrate and S. sanguis with group H antigen were agglutinated with the Helix lectin (Anti-AHP). This suggests that terminal N-acetyl-D-galactsamine of the cell-wall carbohydrate of these bacteria reacts with the Helix lectin (Anti-AHP). Therefore, the Helix lectin is a very useful tool for identification of group C streptococci.