Bactericidal kinetics and postantibiotic effect of sparfloxacin against selected species of respiratory pathogens.

We determined the bactericidal kinetics and postantibiotic effect (PAE) of sparfloxacin against Haemophilus influenzae, Moraxella (Branhamella) catarrhalis, Klebsiella pneumonia, Streptococcus pneumoniae, and Staphylococcus aureus. Time-kill studies were performed by using 1 x and 4 x the minimum inhibitory concentrations (MICs) of sparfloxacin, ciprofloxacin, co-trimoxazole, amoxicillin/clavulanic acid and erythromycin (inoculum 10(5) and 10(7) CFU/ml). The PAE was induced by exposing the strains to 1xMIC and 4xMIC of sparfloxacin and ciprofloxacin for 1 h. Sparfloxacin was the most bactericidal of all the antibiotics tested, being active against Gram-positive and Gram-negative isolates with a 99.9% reduction within 3 to 6 h of exposure, depending upon strain, inoculum and concentration. The PAE of sparfloxacin against all species tested ranged from 1.1 to 2.6 hours; the most notable PAE occurring with M. catarrhalis.