Coaggregation of methicillin-sensitive and -resistant Staphylococcus aureus with oral microorganisms.

The coaggregation of methicillin-sensitive and-resistant Staphylococcus aureus (MSSA and MRSA) with different oral microorganisms, and their aggregation mediated by saliva, were studied. Both types of staphylococci showed similar coaggregation properties. All of the staphylococci, except for one MRSA strain, strongly coaggregated with Fusobacterium nucleatum. Several strains also moderately coaggregated with one strain of Actinomyces naeslundii. Coaggregation with F. nucleatum was completely abolished by heating of F. nucleatum cells. Neither lactose nor EDTA reversed the coaggregation. Streptococcus sanguis competed with staphylococci for coaggregation with F. nucleatum and decreased the cell number of staphylococci interacting with F. nucleatum. Sixteen out of 20 staphylococcal strains were aggregated by whole saliva. These results suggest that both MSSA and MRSA possess the potential to colonize dental plaque and that the suppression of normal microflora as well as saliva-mediated aggregation may influence their colonization.