In vitro activity of Bay 12-8039, a new 8-methoxyquinolone.

MICs of Bay 12-8039 and comparative antimicrobials were determined for 820 recent clinical isolates. Ciprofloxacin was approximately 2-fold more active than Bay 12-8039 and ofloxacin against Enterobacteriaceae and approximately 8-fold more active against Pseudomonas aeruginosa. Bay 12-8039 was approximately 2- to 16-fold more active than ciproiloxacin and ofloxacin against nonfermenters (except P. aeruginosa), staphylococci, streptococci, enterococci, and anaerobes. As determined by regression analysis, there was a high degree of correlation among quinolone MICs.