title: Comparison of in vitro activity of azithromycin and ampicillin against 31 isolates of Streptococcus milleri.
abstract: Antibacterial action of azithromycin against 31 strains of dental infection-derived Streptococcus milleri and tissue transfer of the agent were compared with ampicillin, the drug of first choice for dental infections. Concentrations required to inhibit 50% of isolates(MIC50) and Concentrations required to kill 50% of isolates(MBC50) were 0.10 and 0.2 microgram/ml, respectively, for azithromycin. The antibacterial action of azithromycin was 4 times more potent in than ampicillin. The MBC90 for azithromycin was 0.39 microgram/ml, for amplicill 3.13 micrograms/ml. Bactericidally, azithromycin was 8 times more active than ampicillin. The peak value of concentrations (Cmax) of azithromycin was 0.45 microgram/ml, about 1/10 that of ampicillin. The half-life of azithromycin was 10 hours, about 5 times longer than that of ampicillin. The contact time of MIC90 concentrations for azithromycin was 12 hours, distinctly longer than the 8 hours calculated for ampicillin. Azithromycin showed excellent tissue transfer concentrations: the gingival transfer concentration following oral administration of 500 mg/day ranged from 0.7-23.5 micrograms/ml.
authors.affiliation: Department of Oral Surgery, Tokai University School of Medicine, Kanagawa, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Kaneko
authors.forename: J
authors.initials: J
authors.lastname: Sasaki
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000667:Ampicillin / Q000097:blood / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000097:blood / Q000494:pharmacology*; D017963:Azithromycin / Q000097:blood / Q000494:pharmacology*; D005881:Gingiva / Q000378:metabolism; D006801:Humans; D009994:Osmolar Concentration; D010406:Penicillins / Q000097:blood / Q000494:pharmacology*; D013291:Streptococcus / Q000187:drug effects*
chemical_list: D000900:Anti-Bacterial Agents; D010406:Penicillins; D000667:Ampicillin; D017963:Azithromycin