Bacteriostatic and bactericidal in vitro activities of clarithromycin and erythromycin against periodontopathic Actinobacillus actinomycetemcomitans.

The susceptibilities of 87 periodontitis-associated strains of Actinobacillus actinomycetemcomitans to clarithromycin and erythromycin were determined by standard methodology recommended for Haemophilus influenzae. For clarithromycin the MIC at which 90% of the isolates were inhibited was </=2.0 microg/ml and the minimal bactericidal concentration at which 90% of the strains were killed was </=4.0 microg/ml, suggesting that it would be a candidate for therapeutic trials in patients with periodontitis.