Posaconazole and amphotericin B combination therapy against Cryptococcus neoformans infection

To investigate the effects of posaconazole (POS) and amphotericin B (AMB) combination therapy in cryptococcal infection, we established an experimental model of systemic cryptococcosis in CD1 mice by intravenous injection of three distinct clinical isolates of Cryptococcus neoformans. Therapy was started 24 h after the infection and continued for 10 consecutive days. POS was given at 3 and 10 mg/kg of body weight/day, while AMB was given at 0.3 mg/kg/day. Combination therapy consisted of POS given at a low (combo 3) or at a high (combo 10) dose plus AMB. Survival studies showed that combo 3 was significantly more effective than POS at 3 mg/kg for two isolates tested (P value, less than or equal to0.001), while combo 10 was significantly more effective than POS at 10 mg/kg for all three isolates (P values ranging from <0.001 to 0.005). However, neither combination regimen was more effective than AMB alone. For two isolates, combination therapy was significantly more effective than each single drug at reducing the fungal burden in the brain (P values ranging from 0.001 to 0.015) but not in the lungs. This study demonstrates that the major impact of POS and AMB combination therapy is on brain fungal burden rather than on survival.