Antibacterial Activity of a New Polymeric Local Drug Delivery System on a Multispecies Bacterial Community Associated with Periodontitis

Objectives: Despite improved clinical parameters after scaling/root planing, treatment failure may occur due to the recolonization of the remaining subgingival bacteria. The purpose of this study was to evaluate the antibacterial properties of a topical delivery system using an in vitro multispecies bacterial model. Methods: Minimum inhibitory concentration (MIC) of doxycycline and metronidazole against Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Provetella intermedia and their multispecies mixture was determined. Local drug carrier system based on polycaprolactone/alginic acid loaded by four weight percentages of each drug were prepared by solvent casting method. Sterile drug-loaded specimens (discs with 5 mm diameter) were prepared for the study. The antimicrobial properties of polymeric films were evaluated using disc agar diffusion test (DAD) and planktonic cell count and biofilm formation against bacterial mixture. The data were analyzed by one-way analysis of variance (ANOVA), followed by a post-hoc Tukey test. Results: MIC of doxycycline and metronidazole for multispecies bacterial strains were found 4 and 64 ?g/mL, respectively. DAD test exhibited that all polymeric films had an obvious inhibitory effect on bacterial mixture ranging from 16 to 30 mm. Drug-loaded polymeric films against the multispecies bacterial model significantly reduced both planktonic cell count and biofilm formation compared to control (p < 0.05). By the end of the experiment, our data showed more than 3 log?CFU/mL reduction of number of colonies in all treated groups. Conclusions: All polymeric films followed an accepted antibacterial activity. Of the antibiotics examined in this study, doxycycline-loaded polymeric films were more effective, inhibiting both planktonic and biofilm growth at relatively low concentrations.