A comparison of the penetration of two quinolones into intra-abdominal abscess.

A low-mortality model of an intra-abdominal abscess in the rat has been used to study the penetration of two quinolone agents into pus. Maximum concentrations in pus after intravenous injections were achieved at four hours (ciprofloxacin: 12.7 +/- 3.69 mg/L, fleroxacin: 2.25 +/- 1.82 mg/L), whereas fleroxacin given orally reached the maximum level at two hours (13.39 +/- 3.13 mg/L). Higher concentrations of fleroxacin were recorded in pus than in serum at each time point up to eight hours after administration, but pus levels of ciprofloxacin only exceeded serum levels after 1.5 hours. These antibiotics appear to have a unique property of high penetration into established abscesses and may have an important therapeutic role in the treatment of patients with multiple interloop abscesses.