Bacteriology of dental abscesses of endodontic origin

Aspirates have been cultured from 10 dental abscesses of endodontic origin, all of which had penetrated beyond the bony alveolus to produce fluctuant swelling. Sampling was by syringe aspiration. Strict anaerobic techniques, including the use of an anaerobic chamber, were used for serial dilution and plating. Randomly selected colonies (100) from each culture were purified, characterized, and identified. Seventy percent of the bacterial isolates were either strict anaerobes or microaerophilic. One abscess yielded a pure culture of a viridans streptococcus, Streptococcus milleri. Streptococcus intermedius dominated the flora in a second abscess. The common oral streptococcus, Streptococcus sanguis, constituted only 2% of the isolates from one additional infection. Fusobacterium nucleatum, Bacteroides melaninogenicus, other Bacteroides including B. oralis and B. ruminicola, anaerobic diphtheroids, Peptostreptococcus micros, and Staphylococcus epidermis were other predominant isolates.