Comparative Killing Rates of Fluoroquinolones and Cell Wall-Active Agents

Killing rates of fluoroquinolones, β-lactams, and vancomycin were compared against Enterobacteriaceae, Staphylococcus aureus, pneumococci, streptococci, and Enterococcus faecalis. The times required for fluoroquinolones to decrease viability by 3 log(10) were 1.5 h for Enterobacteriaceae, 4 to 6 h for staphylococci, and ≥6 h for streptococci and enterococci. Thus, the rate of killing by fluoroquinolones is organism group dependent; overall, they killed more rapidly than β-lactams and vancomycin.