ANTIMICROBIAL ACTIVITY OF A NEW FLUOROQUINOLONE, DU-6859A, AGAINST QUINOLONE-RESISTANT CLINICAL ISOLATES OF NEISSERIA-GONORRHOEAE WITH GENETIC ALTERATIONS IN THE GYRA SUBUNIT OF DNA GYRASE AND THE PARC SUBUNITOF TOPOISOMERASE-IV

The in-vitro antimicrobial activity of DU-6859a, a new fluoroquinolone , was tested against 55 clinical isolates of Neisseria gonorrhoeae. Th e MIC of DU-6859a inhibiting 90% (MIC90) of the isolates with genetic alterations of both the GyrA subunit of DNA gyrase and the ParC subuni t of topoisomerase IV was 0.125 mg/L. The MIC90, for isolates with alt erations of GyrA alone or without alterations of GyrA or ParC was 0.03 mg/L and 0.004 mg/L, respectively. The potency of DU-6859a against cl inical isolates bearing genetic alterations associated with quinolone resistance was significantly greater than that of currently available fluoroquinolones.