Identification of Novel Mutation Patterns in the parC Gene of Ciprofloxacin-Resistant Isolates of Neisseria gonorrhoeae

Of 65 ciprofloxacin-resistant, clinical isolates of Neisseria gonorrhoeae, 5 isolates exhibited ParC mutations previously undescribed in the gonococcus. For isolates containing two ParC mutations (the Ser-87→Ile and Glu-91→Gly mutations and the Gly-85→Cys and Arg116→Leu mutations) the MICs of ciprofloxacin (8.0 to 64.0 μg/ml) were higher than those for the isolate containing the single ParC mutation (Arg-116→Leu; MIC, 1.0 μg/ml).