%0 Journal Article %A Ochiai, K. %A Kurita-Ochiai, T. %A Kamino, Y. %A Ikeda, T. %T Effect of co-aggregation on the pathogenicity of oral bacteria %D 1993 %J Journal of Medical Microbiology, %V 39 %N 3 %P 183-190 %@ 1473-5644 %R https://doi.org/10.1099/00222615-39-3-183 %I Microbiology Society, %X Summary The pathogenicity of oral bacteria was studied by measuring the development of subcutaneous abscesses in mice after infection with Actinomyces viscosus and Streptococcus mitis either singly or as co-aggregated pairs. Heat-treated cells were also tested. The pathogenicity of the co-aggregates was examined in various viable and heat-treated combinations of the two bacterial species. More abscesses were formed by A. viscosus than S. mitis at all the bacterial concentrations tested. Also, abscess formation by co-aggregates of the two strains produced a higher percentage of abscess formation than those caused by infection with pure suspensions of A. viscosus or S. mitis. Co-aggregated cells were more resistant to phagocytosis and killing by neutrophils in vitro and in vivo. Furthermore, A. viscosus in co-aggregates were resistant to killing after engulfment by neutrophils. These results suggest that oral bacteria that are able to co-aggregate may resist phagocytosis, and this ability may be linked with pathogenicity. %U https://www.microbiologyresearch.org/content/journal/jmm/10.1099/00222615-39-3-183