In vitro activity of lomefloxacin (NY-198 or SC 47111)

The activity of lomefloxacin was compared to that of four other quinolones. Minimum inhibitory concentrations (MICs) were similar to those of enoxacin, norfloxacin, and ofloxacin against the Enterobacteriaceae, Pseudomonas aeruginosa, Staphylococcus spp. and Enterococcus faecalis. The activity of lomefloxacin was antagonized in urine at pH 5.4, but not in urine at pH 7.0. Higher inocula required higher lomefloxacin concentrations for inhibition. Lomefloxacin was more active at alkaline pH. At concentrations equal to or 2-fold the MIC, it was rapidly bactericidal against Gram-negative organisms and required a longer time for the reduction of inoculum by 99% and 99.9%. An "Eagle effect" was seen against Escherichia coli and Staphylococcus aureus but not against P. aeruginosa.