[Klebsiella pneumoniae infection in immunosuppressed mice treated with gentamicin (author's transl)].

Experiments have been established in order to study the antagonistic effect of cyclophosphamid treatment on the antibiotic activity of gentamicin in vivo. An immunodepressive state in mice (50 % reduction of neutrophil polymorphonuclear) was obtained with a 5 day treatment of cyclophosphamid, at the dose of 15 mg/kg. The mice were inoculated intraperitoneally with 10 LD50 of Klebsiella pneumoniae. Antibiotherapy was applied in 2 ways differing with the dose of gentamicin given twice a day by subcutaneous route (either 2.5 or 25 mg/kg) and with the time at which treatment was started (either at 1 or at 2 h after bacterial challenge). The gentamicin activity decreases in immunosuppressed mice when antibiotic is applied with a low dose (2.5 mg/kg), 1 h after infection challenge. This effect disappears when gentamicin is given with high doses (20 mg/kg) or when antibiotherapy is delayed (2 h after infection challenge). In this case, mortality is important and close to non immunodepressed mice.