Clinical Isolates of Rothia And Haemophilus Coaggregate With Porphyromonas gingivalis
Objectives: investigate the role of Rothia and Haemophilus in biofilm development
Methods: Microscopy (FISH and immunofluorescence) was used to map Rothia and Haemophilus cells in undisturbed biofilm grown intra-orally on enamel chips. Isolates of Rothia mucilaginosa, R. dentocariosa, and Haemophilus parainfluenzae were obtained from the biofilm, then tested for coaggregation against co-isolated bacteria and against a panel of previously cultivated subgingival and caries-associated bacteria.
Results: Within the biofilm, Rothia cells occurred in island-like clusters whereas Haemophilus cells were more evenly distributed. Coaggregations of four representative Rothia isolates and of three representative Haemophilus isolates with members of the same biofilm exceeded those of co-isolated streptococci and actinomyces. Coaggregation of the Rothia/Haemophilus isolates also occurred with Porphyromonas gingivalis strains 33277, 381 and W50, but not with strain W83. The Rothia/Haemophilus isolates coaggregated with Fusobacterium nucleatum PK1594, but not with Tannerella forsythia 43037, Aggregatibacter actinomycetemcomitans VT745, Prevotella intermedia 15032 or Streptococcus mutans UA159.
Conclusions: Conceptual models of plaque development often state that, in general, early colonizers of the tooth surface do not coaggregate with bacteria found in subgingival environments. However, the models rely on data collected primarily on streptococci and actinomyces. Molecular community analyses suggest that Rothia and Haemophilus are present in both health and disease. Isolates of Rothia and Haemophilus examined here coaggregated widely with their co-isolated early colonizers as well as with three of four widely cultivated P. gingivalis strains. Thus, Rothia and Haemophilus may play an important role in bi-directional transition between health and disease. Further study involving a greater number of subgingival and caries-associated strains is warranted.