POSTDEBRIDEMENT BACTERIAL FLORA AND ANTIBIOTIC SENSITIVITY

The postdébridement bacterial flora of root canals in 563 cases was identified and tested as to sensitivity to antibiotics. One or more positive cultures were seen in 23.6 per cent. Only 8.5 per cent yielded more than one positive culture following débridement at each visit and the use of nonspecific antiseptics between visits. Enterococcus was the most persistent organism, although others also persisted. Thirty-two per cent of the vital teeth with a positive culture yielded more than one positive culture, while 40 per cent of the nonvital teeth with a positive postdébridement culture yielded more than one positive culture. Considering all cases, however, teeth with vital or partially vital pulps gave a higher percentage of positive cultures (32 per cent) than nonvital teeth (20 per cent). Antibiotic-sensitivity tests showed novobiocin to be the most effective, followed by penicillin, erythromycin, chloromycetin, and tetracycline. Antibiotics should not be used indiscriminately, however, and the disk test should be performed whenever possible. Penicillin and erythromycin are the drugs of choice in the vast majority of cases. © 1969.