Serological studies on Actinobacillus actinomycetem-comitans.

One hundred strains of Actinobacillus actinomycetem-comitans were examined serologically by determining their agglutination reactions with six absorbed antisera. Twenty-four reaction patterns were found, and the results were reproducible. The agglutinating antigens were heat-stable. Precipitation reactions were also studied by means of the Ouchterlony agar-gel diffusion technique with Fuller and acetone extracts. The agglutination test was considered preferable for epidemiological and ecological investigations on A. actinomycetem-comitans.