COAGGREGATION OF CANDIDA-ALBICANS WITH ORAL FUSOBACTERIUM SPECIES

Nine strains of oral Fusobacterium were examined for their ability to coaggregate in vitro with four strains of the oral yeast, Candida albi cans. All of the Fusobacterium nucleatum strains and Fusobacterium per iodontium and Fusobacterium sulci coaggregated to various degrees with all of the Candida strains. Fusobacterium alocis, Fusobacterium morti ferum and Fusobactrium simiae strains did not coaggregate with any of the Candida strains. Exposure of the coaggregating Fusobacterium strai ns but not the Candida strains to heat, trypsin, and proteinase K elim inated coaggregation. Amphotericin B or trichodermin treatment of the yeast species had no effect. The reactions mere inhibited by addition of 0.1 M mannose, glucosamine and alpha-methyl mannoside. All coaggreg ating pairs were disaggregated by the addition of sodium dodecyl sulfa te, but nonionic detergents had no effect. The addition of 2.0 M urea completely reversed coaggregation. Candida strains were sensitive to p eriodate oxidation, whereas the Fusobacterium strains were stable to t his treatment. All coaggregations occurred in the presence of saliva a nd appeared stronger than in buffer. These data suggest that the coagg regations involve either a protein or glycoprotein on the Fusobacteriu m surface, which may interact with carbohydrates or carbohydrate-conta ining molecules on the surface of the Candida. These observations expa nd the known range of intergeneric coaggregations occurring between hu man oral microbes and indicate that coaggregation of C. albicans Fusob acterium species may be an important Factor in oral colonization by th is yeast. The authors believe this to be the first description of coag gregation concerning a carbohydrate component on the yeast cell and a protein component on the oral bacterial cell.