ANTIMICROBIAL SUSCEPTIBILITY TESTS ON ANAEROBIC ORAL MIXED CULTURES IN PERIODONTAL-DISEASES

The ecosystem of the dental plaque in periodontal diseases is very com plex: the study of such micro-organisms, which are mostly strict anaer obes, requires the use of specific techniques under conditions of stri ct anaerobiosis. The aim of the present study was to design a rapid me thod to evaluate the activity of antimicrobials on mixed bacterial pla que of subjects with periodontal diseases. The study was carried out u sing a computerised instrument generally used for simultaneous diagnos tic tests with aerobic bacteria. Operative and methodological modifica tions were made to obtain conditions of strict anaerobiosis and the ba lanced growth of all the microbial forms present in the mixed cultures of the plaque. Penicillins and cephalosporins were active on all the samples, whereas colistin, gentamicin, kanamycin and nalidixic acid sh owed no activity. Clindamycin, tetracycline, erythromycin and penicill in G were effective only against some samples. The activity of the ant imicrobials towards isolated strains was analogous to that towards the corresponding mixed culture.