0 1988 The Pathological Society of Great Britain and Ireland Assessment of the pathogenicity of bacterial species isolated from acute dentoalveolar abscesses

Summary. The pathogenicity of 20 strains belonging to nine bacterial species isolated from acute dentoalveolar abscesses was assessed individually and in two species combinations by subcutaneous inoculation of mice. Infections were produced by all the bacteria although variations were seen both in the type of lesion produced and the subsequent recovery of viable bacteria. Anaerobic gram-negative bacilli were recovered more often (p < 0-05) at high concentrations ( 106-109 cfulml) and produced a localised abcess with peripheral necrosis more frequently (p < 0.001) than either Streptococcus milleri or anaerobic gram-positive cocci. Lesions induced by a combination of bacteria comprising an anaerobic gram-negative bacillus and any other species yielded both strains at high concentration more often (p < 0.001) than a combination comprising anaerobic gram-positive cocci and S. milleri. It is concluded that anaerobic gram-negative bacilli are major pathogens in acute dentoalveolar abscesses