A rare case of an endobronchial mass due to Neurospora intermedia

The ascomycete filamentous fungus Neurospora intermedia is commonly used in the food industry and considered nonpathogenic to humans. This study characterizes four N. intermedia isolates recovered from three patients. The first patient had a mediastinal germ cell tumor with multiple metastases. N. intermedia was recovered from his endotracheal aspirate and from the endobronchial mass obtained by bronchoscopic forceps biopsy. Histopathology of the biopsy tissue revealed necrotic tissue mixed with septate fungal hyphae with right-angle branching. An endobronchial mass caused by N. intermedia was thus diagnosed. Another two N. intermedia isolates were recovered from the endotracheal aspirates of two critically ill patients. In vitro, N. intermedia grows rapidly and forms orange, conidiating colonies composed of septate hyphae. Two isolates from the first patient belong to mating type a; the other two isolates belong to mating type A. Coculture of isolates of opposite mating types yielded dark ascomata containing ascospores, supporting that N. intermedia is a heterothallic fungus. N. intermedia isolates cross-reacted with the Aspergillus galactomannan antigen assay and were susceptible to amphotericin B and voriconazole. In conclusion, this report describes the first human infection (endobronchial mass) caused by N. intermedia, highlighting its potential to invade the human respiratory tract.