Antibacterial activity of NM394, the active form of prodrug NM441, a new quinolone.

The in vitro antibacterial activity of NM394 was compared with those of other new quinolones. NM394 showed potent and broad-spectrum antibacterial activity against 2,606 recent clinical isolates. The activity of NM394 against gram-positive bacteria was 2- to 16-fold less than that of tosulfoxacin and sparfloxacin but was comparable to that of ofloxacin. Only against Streptococcus pyogenes was the activity of NM394 equal to that of sparfloxacin. Against gram-negative bacteria, NM394 showed antibacterial activity equal to that of ciprofloxacin. Against quinolone-resistant Pseudomonas aeruginosa (norfloxacin MIC, > 6.25 micrograms/ml), the activity of NM394 was greater than those of the other agents tested. NM394 was rapidly bactericidal at concentrations near the MIC. NM394 inhibited supercoiling activities of DNA gyrase purified from Staphylococcus aureus, Escherichia coli, and P. aeruginosa; the 50% inhibitory concentrations were 18.0, 0.41, and 2.05 micrograms/ml, respectively.