Laboratory assessment of lomefloxacin (SC-47111) in comparison with norfloxacin.

The activity of lomefloxacin and norfloxacin against 681 bacterial strains, including 520 strains isolated from infected urine was assessed in vitro. All strains were tested in two inocula and the susceptibility of urinary isolates was evaluated at three pH levels. Lomefloxacin displayed a broad spectrum of antibacterial activity which was similar to that of norfloxacin and which was independent of inoculum size. Good activity was shown for lomefloxacin against all Gram-negative urinary pathogens: strains of Pseudomonas spp and nalidixic acid-resistant enterobacteria were the least susceptible, indicating a degree of cross resistance between newer quinolones and nalidixic acid. Lomefloxacin generally showed more modest activity against Gram-positive cocci and bacteroides than against enterobacteria. Under the acidic conditions that commonly prevail in urine the activity of both compounds against Gram-negative urinary pathogens was markedly reduced, whereas strains of Gram-positive cocci were only minimally affected.