Drosophila melanogaster as a model for the study of Malassezia pachydermatis infections

Malassezia pachydermatis is a yeast that is commonly found in the skin of most animals. Changes in the physical, chemical or immunological processes of the skin may render the host more susceptible to the yeast, which then may cause otitis, dermatitis or, less often, systemic infection. We tested the pathogenicity of M. pachydermatis in wild-type (WT) and Toll-deficient Drosophila melanogaster. Flies were inoculated in the thorax with a needle previously dipped in inoculum concentrations ranging from 103 and 107 yeast cells/mL. After infection, flies were housed at 29 degrees C and mortality was evaluated daily until day seven. WT flies were resistant to the infection, whereas Toll-deficient flies showed inoculum-dependent mortality rates. Fungal burden, assessed by histopathological analysis and by counting the number of colony-forming units of dead flies, corroborated the results. The D. melanogaster model is a promising minihost model for future large-scale studies of virulence mechanisms and antifungal drug activity in malasseziosis.