Murine model of pulmonary mucormycosis in cortisone-treated mice

Intranasal inoculation of Rhizomucor pusillus sporangiospores into cortisone-treated mice produced pulmonary and disseminated mucormycosis (phycomycosis). Evidence for infection in cortisone treated mice was obtained by recovery of Rh. pusillus from homogenates of tissue. Confirmation of infection was shown histologically. The 50% infectious dose was 2.4 x 10(2) colony forming units for lung infections and 2.7 x 10(5) colony forming units for brain infections. No evidence of sporangiospore germination was found in tissues of non-cortisone-treated mice although sporangiospores were found throughout pulmonary tissues. In infected tissues of cortisone-treated mice, hyphae were covered with leukocytes and tissue necrosis was extensive.