Macrolides and changes in the oral flora

Macrolides have been used in dental practice for many years, and may have a role in treating periodontal disease. Increased numbers of antibiotic-resi stant oral streptococci have been reported after administration of both pen icillins and macrolides. We confirm these findings for erythromycin, josamy cin and azithromycin, and show that small numbers of macrolide-resistant st reptococci are part of the normal oral flora at baseline. Resistant organis ms fill the vacuum created by the removal of sensitive strains by antibioti c treatment. Following treatment with azithromycin, periodontal bacterial p athogens such as black pigmented anaerobes and spirochaetes decrease, where as numbers of oral streptococci increase. These changes in the oral flora i ndicate a return to a healthier oral environment. In our studies, no clinic al problems resulted from the transient increase in macrolide-resistant str eptococci. (C) 1999 Elsevier Science B.V. and International Society of Chem otherapy. All rights reserved.