Efficacy of amphotericin B and azoles alone and in combination against disseminated trichosporonosis in neutropenic mice

The activities of amphotericin B, miconazole, fluconazole, and itraconazole against Trichosporon beigelii were assessed in a mouse model of disseminated infection. Cyclophosphamide plus prednisolone-immunosuppressed ICR mice, intravenously challenged with a lethal inoculum of (6 x 10(6) CFU/mouse), were assigned to receive 7 days of therapy with amphotericin B (0.5 or 2 mg/kg/day), miconazole (10 or 40 mg/kg/day), fluconazole (10 or 40 mg/kg/day), or itraconazole (10 and 40 mg/kg/day). The efficacy of a combination of amphotericin B (1 mg/kg/day) with fluconazole (10 mg/kg/day) or itraconazole (20 mg/kg/day) with that of each agent alone was also compared. Both amphotericin B and azoles improved survival and reduced the fungal counts in kidneys of infected mice in a dose-dependent pattern. In general, fluconazole was superior to amphotericin B and the other azoles, whereas the latter two drugs were as effective as amphotericin B. The activity of amphotericin B combined with fluconazole appeared to be superior to that of each agent alone, especially in reducing the organ fungal burden. The other combination (amphotericin B plus itraconazole) had a weaker effect, but no antagonism was observed. In conclusion, azoles may be an alternative to amphotericin B for the treatment of T. beigelii infection. Furthermore, their combination with amphotericin B may improve the poor outcome seen in profoundly neutropenic patients with disseminated trichosporonosis.