Modulation of Klebsiella pneumoniae infection of mice by interferon-gamma.

The aim of this study was to determine the efficacy of interferon-gamma (IFN-gamma) as prophylaxis and therapy in a wound infection model with a 'surgical' pathogen. The bacterial challenge consisted of intramuscular injections of Klebsiella pneumoniae (10(3) organisms in 0.1 ml). Groups of 12 CBA/J mice had either IFN-gamma or RPMI-1640 medium (controls) injected subcutaneously. Mice pretreated with IFN-gamma in a dose of 7,500 or 750 units per day, followed by infection and 2 days additional IFN-gamma treatment, survived significantly longer than controls or mice treated with 150 units of IFN-gamma per day. Significantly greater survival than controls was seen with only 5 or 3 days pretreatment with IFN-gamma but not with 1 day pretreatment. Administration of IFN-gamma to the opposite hind leg from the one receiving bacterial challenge was as effective as same leg treatment. When IFN-gamma therapy was commenced 1 h after bacterial challenge and continued for 7 days, 13 of 60 mice survived, which was significantly greater than four of 60 surviving controls. These effects may be secondary to IFN-gamma's immunoregulatory effects rather than by involving any antiviral properties.