Tentative interpretive criteria and quality control parameters for in-vitro susceptibility testing of Neisseria gonorrhoeae to two fluoroquinolones (PD 131628 and grepafloxacin (OPC 17116)).

The susceptibility of Neisseria gonorrhoeae to PD 131628 and grepafloxacin (OPC 17116) was evaluated by agar dilution and disc diffusion methods. A tentative susceptibility category for both fluoroquinolones included strains for which the MICs are < or = 0.06 mg/L and the zones of inhibition are > or = 38 mm for PD 131628 and > or = 37 mm for grepafloxacin. Quality control studies with N. gonorrhoeae ATCC 49226 suggested that agar dilution MIC limits were 0.002-0.008 mg/L and 0.004-0.03 mg/L for PD 131628 and grepafloxacin, respectively. The zone size limits were 50-58 mm for PD 131628 and 44-52 mm for grepafloxacin.