Anaerobic bacteria in dentoalveolar infections.

The bacteriology of 57 dentoalveolar infections was studied using optimal techniques to collect, transport and process specimens. There was an average of 4 bacterial species per specimen, and only 1/3 of the specimens held aerobes. Among the aerobic bacteria, streptococci dominated and among the anaerobes the Gram-negative rods, Bacteroides ruminicola and Fusobacterium nucleatum, were most frequently isolated followed by Gram-positive cocci, in particular Streptococcus intermedius. All aerobic isolates were resistant to penicillins but sensitive to clindamycin and tinidazole. The other anaerobic isolates were sensitive to penicillins but showed varying susceptibility to erythromycin and doxycycline. Tinidazole was effective against all anaerobic Gram-negative rods. The presence of volatile fatty acids in pus from dentoalveolar infections was found to be of presumptive value for the diagnosis of anaerobic infections. Direct gas-liquid chromatographic analysis of pus is recommended as a routine procedure for preliminary diagnosis of anaerobic dentoalveolar infections.