Hydrocortisone, prednisolone and dexamethasone act on Aspergillus fumigatus in vitro susceptibility to itraconazole.
In a previous in vitro investigation from the same laboratory a therapeutic level of hydrocortisone enhanced the itraconazole susceptibility of a single strain of Aspergillus fumigatus. In the present work, the influence of therapeutic levels of hydrocortisone (1 microM), prednisolone (0.125 microM 0.25 microM and 0.5 microM) and dexamethasone (0.25 microM and 0.5 microM) on the itraconazole susceptibility of four A. fumigatus strains, was determined. A. fumigatus conidia were germinated either in the absence or in the presence of a glucocorticoid. The germinated conidia were then spread onto plates and grown either in the presence or in the absence of a glucocorticoid, together with increasing concentrations of itraconazole. The mean colony forming units (CFU) were measured. Two factor analyses of variance showed that hydrocortisone significantly (p <0.001) potentiated the action of itraconazole. The cytotoxic effect of prednisolone on the fungal strains added significantly to the effect of itraconazole (p <0.001). Dexamethasone was also cytotoxic to the fungus but, when used in conjunction with itraconazole, it effectively increased (p <0.01) the number of CFU. This study showed a direct effect of glucocorticoids, currently in use for patient therapy, on in vitro A. fumigatus susceptibility to itraconazole.
Département Interaction Cellulaire Parasite H te, Faculté de Médecine et de Pharmacie, La Tronche, France.
I
I
Ramondenc
C
C
Pinel
S
S
Parat
P
P
Ambroise-Thomas
R
R
Grillot
D000935:Antifungal Agents / Q000494:pharmacology*; D001228:Aspergillosis / Q000188:drug therapy; D001232:Aspergillus fumigatus / Q000187:drug effects* / Q000254:growth & development; D015169:Colony Count, Microbial; D003907:Dexamethasone / Q000494:pharmacology; D004357:Drug Synergism; D005938:Glucocorticoids / Q000494:pharmacology*; D006801:Humans; D006854:Hydrocortisone / Q000494:pharmacology; D017964:Itraconazole / Q000494:pharmacology*; D011239:Prednisolone / Q000494:pharmacology; D018709:Statistics, Nonparametric
D000935:Antifungal Agents; D005938:Glucocorticoids; D017964:Itraconazole; D003907:Dexamethasone; D011239:Prednisolone; D006854:Hydrocortisone