In vitro antimicrobial activity and postantibiotic effect of lomefloxacin, a new difluoroquinolone

The in vitro activity of lomefloxacin, a new difluorinated quinolone, was compared with that of ofloxacin and norfloxacin against 154 Gram-negative and 200 Gram-positive aerobes freshly isolated from clinical specimens. MIC and MBC values were in the range of those reported in the literature showing lomefloxacin as potent as the other quinolones tested. Time-kill studies indicated that this drug was rapidly bactericidal against Gram-negative and staphylococcal isolates. After 6 hr survivors were reduced to 0.1% with both Enterobacteriaceae and Staphylococcus strains, and to 0.01% with Pseudomonas aeruginosa isolates. A postantibiotic effect of about 2 hr was observed with Gram-negative bacteria and staphylococci exposed for 1 hr to a concentration of lomefloxacin corresponding to 4 x MIC. The results obtained indicate that lomefloxacin compares favorably with the other drugs tested.