Efficacy of ofloxacin (HOE 280) in a model of subcutaneous abscess: penetration and prevention of abscess formation.

A mouse model of subcutaneous abscess was used to determine the penetration into the abscess and the preventive value of ofloxacin (Hoe 280). Sterile cecal contents were injected subcutaneously combined with three different types of inoculum: Bacteroides fragilis, Escherichia coli and E. coli plus B. fragilis. For penetration studies three doses of 20 mg/kg of ofloxacin were administered intraperitoneally 8 hourly after abscesses had formed. Serum levels at 10, 20, 30, 60 and 90 min after the last dose showed mean values of: 6.9, 4.7, 3.8, 2.35 and 1.08 mg/l respectively. Simultaneously assessed ofloxacin abscess levels were 3.6, 4.1, 2.4, 1.91 and 1.98 mg/kg. In order to evaluate its preventive value, ofloxacin was given intraperitoneally at doses of 20 mg/kg in four regimens. Regimen A: one dose immediately before injection of the inoculum; regimen B: one dose 4 h after the injection of the inoculum; regimen C: one dose immediately before and two doses 8 h and 16 h after injection of the inoculum and regimen D: one dose 4 h, 12 h and 20 h after injection of the inoculum. The results are expressed as the percentage of the reduction in the number of abscesses formed in the survivors versus the control groups: regimens A) 30 to 70%; B) 0 to 40%; C) 50 to 60%, and D) 10 to 60%. The viable bacterial counts in the abscess contents were also assessed.