Bactericidal activities of ten different fluoroquinolones against selected Enterobacteriaceae

Ten fluoroquinolone compounds and two other 4-quinolones were tested in a microdilution system. Minimal inhibitory concentrations and minimal bactericidal concentrations were determined with 1 X 10(7) and 5 X 10(5) colony forming units per milliliter. All 12 compounds were bactericidal. Continued inhibition by drug carried over in the subcultured samples was documented and that represents a potential source of technical error that needs to be controlled when determining minimal bactericidal concentrations for these extremely potent drugs.