SALIVA-INDUCED AGGREGATION OF ORAL STREPTOCOCCI AND THE INFLUENCE OF BLOOD-GROUP REACTIVE SUBSTANCES

Aggregation of strains of Streptococcus rattus, Strep. mutans and Strep. salivarius by saliva from individual of blood groups A, B and o was investigated. Blood group A salivas had a significantly higher aggregation activity with Strep. rattus than blood group B salivas (P < 0.05). However, Strep. mutans and Strep. salivarius were better aggregated by blood group B saliva and this was significant for Strep. mutans (P < 0.05). For all three strains, the variance within blood group O was too large to give significant difference with either blood group A or B. The blood group A-specific carbohydrate, N-acetyl-D-galactosamine, inhibited aggregation of Strep. rattus, but not of the other strains. The blood group B-specific carbohydrate, D-galactose, inhibited aggregation of Step. mutans but not of Strep. rattus or Strep. salivarius. L-Fucose, specific for blood group O failed to inhibit aggregation of any of the three strains. These findings suggest that blood group-specific substances may be involved in bacterial aggregation.