In vitro activity of lomefloxacin, a difluorinated quinolone, compared with other antimicrobials

A total of 3,144 clinical isolates from 3,011 consecutive patients were tested against lomefloxacin by the agar dilution method. They consisted of 1,380 isolates of Enterobacteriaceae, 527 pseudomonads, 47 Haemophilus influenzae, 53 Acinetobacter, 42 Brucella melitensis, 903 staphylococci and 192 strains of enterococci. In vitro activity of lomefloxacin was compared with ciprofloxacin, norfloxacin, beta-lactams and aminoglycosides. Over 98% of Enterobacteriaceae were susceptible to lomefloxacin with an MIC of 0.06-4.0 micrograms/ml. It also inhibited 93 and 85% clinical isolates of Pseudomonas aeruginosa and Xanthomonas maltophilia, respectively. All isolates of Haemophilus, Brucella and Staphylococcus aureus were susceptible to this fluoroquinolone. However, only 43% of the 192 strains of enterococci exhibited in vitro susceptibility. Lomefloxacin was found to be comparable to ciprofloxacin and norfloxacin in its in vitro activity, and superior to most penicillins, cephalosporins and aminoglycosides against both gram-negative and gram-positive bacteria except enterococci.