Coaggregations among oral bacteria.

The oral bacterial community appears to use coaggregation as a major mechanism for interbacterial adhesion and colonization of the host. Methods for measuring and evaluating the specificity of adhesion vary from the visual observation of the phenomenon to quantitative analyses. Not only is aggregation specificity reflected in the choice of partners but also in the fact that many are inhibited by galactosides and sialic acid. Each coaggregation between any two partners within a multigeneric coaggregate is independent of the others and can be shown to be distinct by using the radioactivity-based assay. By using the visual assay, it has been shown that members of the 17 genera of most frequently isolated oral bacteria exhibit coaggregation. With the exception of oral streptococci and a few oral actinomyces, the 17 genera do not exhibit intrageneric coaggregation. As a dynamic population, oral bacteria are in a constant flux of accretion and detachment, which are coupled to growth and death. This ecological community is amenable to intensive study, and the coaggregation assays described here are particularly suited to enhance progress in this study.