Coaggregation of black-pigmented Bacteroides species with other oral bacteria.

Coaggregation of Bacteroides gingivalis and other black-pigmented bacteroides with several oral bacteria was studied with "reagent" strains specially prepared by methods that have been described previously. B. gingivalis coaggregated with Veillonella, Capnocytophaga and Actinomyces spp., but not with any Streptococcus spp. Coaggregation of B. gingivalis with other bacteria was inhibited and reversed by lactose. Of the asaccharolytic black-pigmented bacteroides, only B. gingivalis demonstrated any coaggregation with other bacteria, whereas within the saccharolytic species, B. loescheii showed a marked ability to coaggregate with several species of oral bacteria. This property of coaggregation by B. gingivalis may be an important factor in the pathogenesis of periodontal infections.