Antibacterial activity of grepafloxacin.

Grepafloxacin has an extremely broad spectrum of activity. Its activity against Gram-positive bacteria exceeds that of currently available quinolones. Grepafloxacin-resistant mutants seem to occur less frequently than ciprofloxacin- or ofloxacin-resistant mutants, and the increase in MIC against the former mutants is less than that of the latter. This applies only to the relative differences (in dilution steps); the absolute values are similar. Grepafloxacin kills Gram-positive bacteria at concentrations little above the MIC. Its pharmacodynamic profile against pneumococci is promising, favouring use of this drug for respiratory tract infections.