Phaeoacremonium parasiticum invasive infections and airway colonization characterized by agar block smear and ITS and β-tubulin gene sequencing.

Phaeoacremonium parasiticum is an environmental dematiaceous mold rarely associated with human infections. We present here 2 cases of P. parasiticum invasive infections, including the first report of P. parasiticum respiratory tract infection, and 1 case of airway colonization, which all 3 strains of P. parasiticum were identified using agar block smear and ITS and β-tubulin gene sequencing. All 3 isolates grew initially as white to creamy, yeast-like colonies. After 21 days of incubation at 25 °C, 1 isolate remained light brown, atypical of P. parasiticum. Microscopic examination of agar block smear preparations of all 3 isolates showed thick-walled, medium brown conidiophores that were branched and slightly swollen at the base. The sequences of the ITS and β-tubulin genes of the 3 isolates were identical to those of P. parasiticum. Cases of P. parasiticum infections should be confirmed by a polyphasic approach using morphologic characterization and ITS and β-tubulin gene sequencing.