The killing action of fleroxacin upon Bacteroides fragilis

The killing kinetics of fleroxacin against four strains of Bacteroides fragilis were investigated. Viable counts were determined from 0 to 24 h after exposure to fleroxacin at multiples of the MIC. A one to three log reduction in viable count was observed after 2 h at 8 mg/l fleroxacin, and a more rapid rate of killing was seen at greater concentrations of the antimicrobial agent. An increase in cell length was observed at concentrations at and above the MIC from 2 h after exposure. The presence of a bacteriostatic concentration of chloramphenicol had negligible influence on viability but inhibited cell elongation.