Antimicrobial interference of a subinhibitory concentration of azithromycin on fimbrial production of Porphyromonas gingivalis.

The first pathogenic mechanism of Porphyromonas gingivalis, which is mainly responsible for adult periodontal diseases, is the attachment of fimbriae appendages to oral epithelial cells. The ability of a subinhibitory concentration of azithromycin to inhibit the expression of fimbriae in various strains of P. gingivalis isolated was investigated. A one-eighth subinhibitory concentration of azithromycin was evaluated in vitro. The antibiotic was active in 75% of P. gingivalis strains isolated, judged by both electrophoresis and transmission electron microscopy. The results indicate that the subinhibitory concentration of azithromycin is capable of blocking the pathogenic mechanism of P. gingivalis in vitro, and, therefore, can be used in vivo as a treatment for recurrent periodontitis.