Cohesion between oral streptococci and Neisseria pharyngis on saliva-coated glass, in the presence and absence of sucrose.

Ten strains of oral streptococci, comprising nine species, were screened for their in vitro cohesive interactions with a freshly isolated strain of Neisseria pharyngis. Strains of mutans streptococci, Streptococcus salivarius, Streptococcus sanguis I, Streptococcus milleri and Streptococcus mitis were able to cohere with N. pharyngis cells attached to a salivary pellicle adsorbed to glass. The cohesion was either due to coaggregation between the different genera or modification of the salivary pellicle by N. pharyngis MW2. S. sanguis II and Streptococcus oralis strains could not cohere with the N. pharyngis strain. Extracellular polysaccharide formed from sucrose was found to mediate cohesion between certain strains of mutans streptococci or S. oralis and N. pharyngis MW2.