IN-VIVO ORAL EFFICACY OF LEVOFLOXACIN FOR TREATMENT OF SYSTEMIC PSEUDOMONAS-AERUGINOSA INFECTIONS IN A MURINE MODEL OF SEPTICEMIA

The in vivo efficacies of levofloxacin and ciprofloxacin in lethal, sy stemic Pseudomonas aeruginosa infections in mice were compared. MICs o f levofloxacin and ciprofloxacin ranged from 0.5 to 2.0 mu g/ml and fr om 0.12 to 1.0 mu g/ml, respectively. Infecting doses ranged from 5.0 x 10(1) to 3.2 x 10(3) CFU per mouse, depending on the isolate, Test f luoroquinolones were administered orally at 1 h (single dose) or at 1 and 3 h (divided dose) postinfection, with 10 infected mice used for e ach of six concentrations of each fluoroquinolone tested (1 to 40 mg/k g of body weight) in each dosing regimen, Whether given in a single or a divided dose, the total daily dose was the same for each fluoroquin olone, For mice treated 1 h postinfection with levofloxacin and ciprof loxacin, the effective doses for 50% of the infected mice ranged from 2.09 to 13.80 mg/kg and from 2.34 to 11.22 mg/kg, respectively, and fo r those treated 1 and 3 h postinfection, the effective doses for 50% o f the infected mite ranged from 3.71 to 16.98 mg/kg and from 2.95 to 1 3.18 mg/kg, respectively, Although the potency varied for both levoflo xacin and ciprofloxacin among all strains of P. aeruginosa tested, the re were small differences within the same strain for levofloxacin and ciprofloxacin when given in the same dosing regimen, Levofloxacin prov ed nearly as effective as ciprofloxacin against a systemic P. aerugino sa infection in mice.