Differentiation of fluorinated quinolone antibacterials with Neisseria gonorrhoeae isolates

Clinical isolates of Neisseria gonorrhoeae were tested for growth inhibition by various quinolones. One acrosoxacin-resistant isolate was also resistant to several fluorinated quinolones with 7-heterocyclic substitution, but, inhibitory concentrations were not elevated for quinolones substituted with a methyl group in the corresponding position (nalidixic acid:position 7, S-25930:position 8) or unsubstituted (flumequine:position 8). Isolates resistant to flumequine demonstrated elevated inhibitory concentrations for all quinolones examined.