BACTERICIDAL ACTIVITY AND POSTANTIBIOTIC EFFECT OF CLARITHROMYCIN AND14-HYDROXYCLARITHROMYCIN, ALONE AND IN COMBINATION, AGAINST LEGIONELLA-PNEUMOPHILA

Time-kill curves using simulated peak and trough serum concentrations, and postantibiotic effect (PAE) were determined for clarithromycin an d 14-hydroxyclarithromycin alone and in combination against four strai ns of Legionella pneumophila. Both compounds were bactericidal at both peak and trough concentrations. The combination at trough concentrati ons demonstrated lower killing activity than the parent drug in three of the four strains. PAE ranges were 7.28-17.3 h for clarithromycin, 6 .78-14.77 h for the metabolite, and 5.15-13.23 h for the combination.