[In vitro and in vivo antibacterial activities of azithromycin]

In Vitro and in vivo antibacterial activities of azithromycin were compared with those of macrolides and other antimicrobial agents. In the in vitro activity azithromycin has a potent activity against both gram-positive and gram-negative bacteria, but against the latter organisms the other macrolides have little potent activity. The in vitro results demonstrate that azithromycin has a high potent activity against respiratory pathogens such as erythromycin-susceptible staphylococci, streptococci (except for organisms possessing erm gene), H, influenzae, B. prtussis, Legionella spp., M. pneumoniae, C. trachomatis. In the pharmacokinetic of azithromycin in mice, it is found that its half life is longer than the other macrolides and the concentration of it in polymorphonuclear leukocytes and lung tissues is higher than the other macrolides. These specific properties in the pharmacodynamic and the in vitro antibacterial activities reflect the therapeutic efficacies in experimental infection models. Finally, the therapeutic efficacies of azithromycin in various infection models better than those of the other macrolides.