In the present study, we have investigated some growth conditions capable of inducing the conidial germination
in
Scedosporium apiospermum,
S. aurantiacum,
S. minutisporum and
Lomentospora prolificans. Germination
in Sabouraud medium (pH 7.0, 37ºC, 5% CO
2) showed to be a typically time-dependent event, reaching ~75% in
S. minutisporum and > 90% in
S. apiospermum,
S. aurantiacum and
L. prolificans after 4 h. Similar germination
rate was observed when conidia were incubated under different media and pHs. Contrarily, temperature and CO
2 tension modulated the germination. The isotropic conidial growth (swelling) and germ tube-like projection were
evidenced by microscopy and cytometry. Morphometric parameters augmented in a time-dependent fashion, evidencing
changes in size and granularity of fungal cells compared with dormant 0 h conidia. In parallel, a clear
increase in the mitochondrial activity was measured during the transformation of conidia-into-germinated conidia.
Susceptibility profiles to itraconazole, fluconazole, voriconazole, amphotericin B and caspofungin varied regarding
each morphotype and each fungal species. Overall, the minimal inhibitory concentrations for hyphae were higher
than conidia and germinated conidia, except for caspofungin. Collectively, our study add new data about the conidia-
into-hyphae transformation in
Scedosporium
and
Lomentospora species, which is a relevant biological process
of these molds directly connected to their antifungal resistance and pathogenicity mechanisms.