Resumen de Modulation of Porphyromonas Gingivalis Proteinase Activity by Suboptimal Doses of Antimicrobial Agents
Daniel Grenier, Elizabeth Roy, Denis Mayrand
Background: Antimicrobial agents are sometimes used as adjuncts for the treatment of aggressive and refractory forms of periodontitis. In this study, we used a culture plate assay to investigate the effect of suboptimal doses of antimicrobial agents on proteinase activity of Porphyromonas gingivalis.
Methods: A culture plate assay using gelatin as the substrate, which allows a semiquantitative determination of proteinase activity, was developed. Suboptimal inhibitory concentrations of tetracycline, minocycline, doxycycline, metronidazole, penicillin G, or chlorhexidine were added to the medium, and proteolysis zones were determined following the growth of three strains of P. gingivalis. The effect of antimicrobials on outer membrane vesicleassociated gingipains also was determined.
Results: The gelatin plate assay was a convenient, simple procedure for investigating the effect of suboptimal inhibitory concentrations of antimicrobial agents on proteinases produced by P. gingivalis. The largest reduction (>75%) in the proteolysis zones produced by three strains of P. gingivalis. was obtained with minocycline. Tetracycline and doxycycline also reduced the proteolysis zones. A suboptimal inhibitory concentration of chlorhexidine increased the proteolysis zones by up to 70%. Metronidazole and penicillin G produced no noticeable effect. The suboptimal inhibitory concentrations of minocycline, tetracycline, and doxycyline did not reduce the activity of outer membrane vesicleassociated Arg- and Lys-gingipains.
Conclusion: Results from this study suggest that sublethal concentrations of some antimicrobial agents in subgingival sites have the potential to affect the physiology of P. gingivalis., notably by increasing or decreasing the proteolytic activity of the bacteria. J Periodontol 2003;74:1316-1319.
