Louis D. Saravolatz, Section Editor

The usefulness of fluoroquinolones for the treatment of mixed aerobic and anaerobic infections has been investigated since these agents started being used in clinical practice. Newer compounds have increased in vitro activity against anaerobes, but clinically relevant susceptibility breakpoints for these bacteria have not been established. Pharmacodynamic analyses and corroboration by new data from clinical trials have enhanced our knowledge concerning the use of fluoroquinolones to treat selective anaerobic pathogens. These studies suggest that newer agents could be useful in the treatment of several types of mixed aerobic and anaerobic infections, including skin and soft-tissue, intra-abdominal, and respiratory infections. The major concerns with expanding the use of fluoroquinolones to treat anaerobic infections have been reports of increasing resistance in Bacteroides group isolates and the impact of these antibiotics on the incidence of Clostridium difficile–associated disease. Since the introduction of ciprofloxacin, there has been con-tinuing interest in the ability of fluoroquinolones to treat in-fections involving anaerobic bacteria [1]. Ciprofloxacin lacked in vitro potency against many important anaerobic bacteria, but several newer quinolones looked promising [2–6]. Trova-floxacin was the first fluoroquinolone to receive approval from the US Food and Drug Administration for the treatment o