Experimental study of pathogens of odontogenic infection, using an oral floor abscess model in mice. Mechanism of microbial interactions between Streptococcus constellatus and Fusobacterium nucleatum.

In the present study, microbial interactions between Streptococcus constellatus and Fusobacterium nucleatum, which are isolated frequently in odontogenic infections, were examined using an oral floor abscess model in mice. Microbial interactions between the two tested strains were observed. The culture filtrate of S. constellatus did not enhance F. nucleatum virulence. However, it appeared that the culture filtrate of F. nucleatum enhanced S. constellatus virulence. Moreover, this enhancement was observed when a heat-treated culture filtrate of F. nucleatum was injected. These findings suggest that a heat-stable substance in F. nucleatum culture filtrate may play an important role in microbial synergy between S. constellatus and F. nucleatum.