[In vitro activity of new quinolones against nonfermenters and references to sensitivity tests]

Studies of cross resistance between norfloxacin, ofloxacin, enoxacin and ciprofloxacin using 599 strains of non-fermentative gram-negative rods (297 Pseudomonas spp. and 302 Acinetobacter spp.) resulted in nearly identical minimal inhibitory concentrations of norfloxacin and enoxacin Comparing MIC values, in most ofloxacin was one to four dilution steps superior to enoxacin, and ciprofloxacin was one to four dilution steps superior to ofloxacin. There was not much difference in MICs when species were studied in more detail. In some instances susceptibility testing with more than one new quinolone may be necessary, and evaluation criteria are given.