In vitro assessment of CI-934--a new quinolone derivative.

CI-934 is a new broad-spectrum fluoroquinolone. We have studied its in vitro activity against 203 bacteria and compared it with ciprofloxacin, enoxacin, ampicillin, cefuroxime, cefotaxime, gentamicin, vancomycin and erythromycin. Against Gram-negative pathogens CI-934 showed broad-spectrum activity comparable to enoxacin. Of more interest is its superior activity against Gram-positive bacteria, especially Streptococcus pneumoniae and enterococci. This was further studied by observing its activity in comparison with ampicillin in in vitro kinetic studies. CI-934 was either equally or more rapidly bactericidal than ampicillin at concentrations of 1, 4, and 16 X MIC. On the basis of these findings further in vivo studies appear justified.