In vitro evaluation of antibiotics in the treatment of periodontal disease.

To assess the antibiotic sensitivity of subgingival microflora, chloramphenicol sodium succinate, clindamycin hydrochloride hydrate, disodium carbenicillin, doxycycline hyclate, erythromycin, minocycline hydrochloride, penicillin -G, spiramycin adipate, tetracycline hydrochloride and metronidazole were examined. Eleven patients with periodontitis were selected for sampling. Subgingival plaque samples were taken from three sites on each patient. Anaerobic incubation of the plaque samples for ten days was made on the blood agar plates which contained 0.1 microgram/ml and 5 microgram/ml of each antibiotic substance, respectively. According to the results of viable counts on the plates, it was determined that penicillin, tetracycline, doxycycline, and minocycline were most effective antibiotics with which to control the periodontal plaque organisms. Resistant organisms against those four antibiotics were generally Streptococcus species. "anaerobic vibrios", and Veillonella parvula. Some of the oral anaerobic isolates were also tested against all antibiotics at the concentration of 1 microgram/ml of each. Minocycline and clindamycin were the two most effective antibiotics against anaerobic subgingival purified strains and chloramphenicol was the least effective.