title: Effect of co-aggregation on the pathogenicity of oral bacteria.
abstract: 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.
authors.affiliation: Department of Microbiology, Nihon University, School of Dentistry at Matsudo, Chiba, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Ochiai
authors.forename: T
authors.initials: T
authors.lastname: Kurita-Ochiai
authors.forename: Y
authors.initials: Y
authors.lastname: Kamino
authors.forename: T
authors.initials: T
authors.lastname: Ikeda
mesh_terms: D000038:Abscess / Q000382:microbiology; D000190:Actinomyces / Q000276:immunology / Q000472:pathogenicity*; D000196:Actinomycosis / Q000382:microbiology*; D000371:Agglutination; D000818:Animals; D003731:Dental Caries / Q000382:microbiology; D003773:Dental Plaque / Q000382:microbiology; D006801:Humans; D008297:Male; D051379:Mice; D009055:Mouth / Q000382:microbiology*; D009504:Neutrophils / Q000276:immunology; D010514:Periodontal Pocket / Q000382:microbiology; D010587:Phagocytosis; D013290:Streptococcal Infections / Q000382:microbiology*; D013291:Streptococcus / Q000276:immunology / Q000472:pathogenicity*