Anaerobic flora in endodontic infections.

Microbiological and clinical data from 56 patients with endodontic infections were evaluated. Samples were collected using autoclaved paper points. Specimens were processed for isolation of aerobic and anaerobic bacteria. Antimicrobial sensitivity and resistance profiles of the recovered isolates was also performed. Forty nine positive cultures (87.5%) were obtained from the 56 consecutive necrotic root canal systems which were sampled. A total of 69 aerobic bacteria and 21 anaerobic bacteria were recovered. Aerobic bacteria were isolated from 35 patients (72%), anaerobic bacteria from 3 (6%) and mixed aerobic and anaerobic bacteria from 11 patients (22%). The most common aerobic isolate was Klebsiella pneumoniae. The predominant anaerobic isolate was Bacteroides species. One isolate was recovered from 25 patients (51%) whereas in the remaining 24 patients (49%) more than 1 isolate were recovered. These data illustrate the polymicrobial nature of endodontic infections in half the patients studied and the role of anaerobic bacteria in a quarter of them.