The in-vitro activity of OPC-17116, a new 5-methyl substituted quinolone.

The in-vitro activity of the new 5-methylated fluoroquinolone OPC-17116 was compared with that of other fluoroquinolines and beta-lactams against a total of 690 bacterial strains. With the exception of Klebsiella and Serratia spp., 90% of the Enterobacteriaceae were inhibited by 0.25 mg/L. OPC-17116 inhibited 90% of Serratia spp. at 8 mg/L and Klebsiella spp. at 4 mg/L. Moraxella catarrhalis and Haemophilus influenzae were highly susceptible (MIC90 < or = 0.03 mg/L). Pseudomonas aeruginosa were more susceptible to ciprofloxacin (MIC90 0.25 mg/L) than OPC-17116 (MIC90 1 mg/L). Generally, OPC-17116 was more active than ciprofloxacin against Gram-positive cocci, 90% of Staphylococcus spp. being inhibited by < or = 0.25 mg/L. OPC-17116 displayed greater activity than ciprofloxacin against Chlamydia spp. (MICs < or = 0.12 and < or = 2 mg/L, respectively).