Antibacterial activity and post-antibiotic effect of flurithromycin compared with other macrolides and penicillins against periodontal pathogens

In this study the authors examined the activity of flurithromycin compared to that of erythromycin, spiramycin and penicillin against 107 strains of various species supposed to cause periodontitis. The range of MICs of flurithromycin was: ≤0.06-2 mg/l for P. gingivalis (28 isolates), 0.06-2 mg/l for P. melaninogenica (7), 0.5-4 mg/l for P. intermedia (5), 0.25-8 mg/l for Prevotella sp. (8), 1-16 mg/l for F. nucleatum (14), 0.12-0.5 mg/l for W. recta (2), 0.5-32 mg/l for E. corrodens, 0.5-2 mg/l for B. forsythus (2); ≤0.06-64 mg/l for Peptostreptococcus sp. (11), ≤0.06-1 mg/l for A. odontolyticus (11) and for A. naeslundii (7) and ≤0.06-16 mg/l for A. viscosus (7). Macrolide activity was ranked in decreasing order from flurithromycin to erythromycin to spiramycin. Beta-lactamase production was demonstrated in Prevotella sp. (20%) and in F. nucleatum (7%). Isolates which were β-lactamase negative but resistant to penicillin were found among Peptostreptococcus sp. and Actinomyces sp. A post-antibiotic effect of 2 hours was seen for flurithromycin on P. gingivalis and E. corrodens. The good in vitro activity of flurithromycin against bacteria supposed to cause periodontitis suggests clinical potential in the treatment of these diseases.