In vitro activity of lomefloxacin and other antimicrobials against bacterial enteritis pathogens

Lomefloxacin is a new, difluoroquinolone. In this study, the in vitro activity of lomefloxacin against clinical isolates of a variety of bacterial species associated with acute diarrheal disease was determined and compared with that of ciprofloxacin, ofloxacin, amoxicillin, sulphamethoxazole, trimethoprim, tetracycline, and chloramphenicol. Bacterial isolates were obtained from different geographical areas, including Western Europe and the United Kingdom, Southern Europe, Africa, the Middle East, South and Southeast Asia, and South America, and were included to reflect the range of susceptibility seen throughout the world. Minimum inhibitory concentrations (MICs) were determined using an agar incorporation technique in Mueller-Hinton medium supplemented when necessary with saponin-lysed horse blood at a final concentration of 10% vol/vol. Lomefloxacin was highly active against all the species examined which included Salmonella spp., Shigella spp., Escherichia coli enterotoxigenic [(ETEC), enteroinvasive (EIEC), and enteropathogenic (EPEC) strains], Yersinia enterocolitica, Campylobacter jejuni, Vibrio spp., and Aeromonas hydrophila, with all isolates inhibited by 1 mg/L or less. This activity was similar to ofloxacin and slightly less than that of ciprofloxacin. By contrast, many of the isolates were resistant to one or more of the other, unrelated animicrobials. No cross-resistance between lomefloxacin and any of the nonfluoroquinolone antimicrobials examined in the study was observed.