Antimicrobial activity of BMS 284756 (T-3811) against Neisseria gonorrhoeae tested by three methods

The potency of BMS 284756, a novel des-F(6)-quinolone, was tested against 137 clinical isolates of Neisseria gonorrhoeae including 50 strains observed to be resistant to ciprofloxacin and other newer quinolones. The gonococci were tested using NCCLS methods (agar dilution, disk diffusion) and Etest. BMS 284756 potency versus N. gonorrhoeae was generally two- to four-fold greater than ciprofloxacin. Penicillin resistance in the absence of ciprofloxacin resistance did not affect BMS 284756 activity. However, elevated ciprofloxacin MICs were associated with higher BMS 284756 MIC results as follows (BMS 284756 MIC(50)/MIC range in mg/l): ciprofloxacin-susceptible strains (0.016 or 0.03/0.004-0.06), ciprofloxacin-intermediate strains (0.06 or 0.12/0.008-0.25) and ciprofloxacin-resistant strains (0.12 or 0.5/0.12-1). Etest MICs were routinely lower than those produced by the reference agar dilution method, but the correlation coefficient remained acceptable (r = 0.87). Similarly acceptable correlation was achieved with 5 microg disk zone diameters (r = 0.78), where all zones were > or = 28 mm (MIC < or = 1 mg/l). In conclusion, BMS 284756 was very active against N. gonorrhoeae (MIC(50) 0.03 mg/l overall) including ciprofloxacin-resistant strains and could be considered as a single-dose therapeutic option for gonorrhoea.