In vitro assessment of the postantibiotic effect of lomefloxacin against gram-positive and gram-negative pathogens

We evaluated the postantibiotic effect (PAE) of lomefloxacin, a new difluorinated quinolone, on multiply drug-resistant gram-positive and gram-negative clinical pathogens. Lomefloxacin induced a PAE of about 2 hours in gram-negative and gram-positive bacteria exposed for 1 hour to concentrations corresponding to four times their minimum inhibitory concentrations (MIC). PAE values (hours) ranged from 1.8 with Serratia marcescens to 2.5 with Staphylococcus aureus. No significant differences in PAE values were found for ciprofloxacin or ofloxacin against the same pathogens. The PAE was increased when the time of drug exposure was increased to 2 hours. These results indicate that lomefloxacin has a PAE equivalent to that of other fluoroquinolones.