Chaetomium atrobrunneum and Aspergillus fumigatus in multiple tracheal aspirates: Copathogens or symbiosis

Chaetomium atrobrunneum has never been reported to be associated with pneumonia. We report the isolation of C. atrobrunneum and Aspergillus fumigatus from a Chinese elderly patient with fatal pneumonia. Branched, long, and septate hyphae were observed in potassium hydroxide preparations and Gram-stained smears, and confluent C. atrobrunneum growth and a few A. fumigatus colonies were found in tracheal aspirates (nine separate occasions). These isolates were identified by conventional morphological methods and by sequencing the internal transcribed spacer and the D1/D2 domain of the 26S rRNA gene. The patient responded poorly to the combination therapy of amphotericin B and caspofungin. This report adds C. atrobrunneum to the list of fungal pneumonia in immunocompromised hosts. This case report also illustrated the presence of a growth symbiosis between Chaetomium species and A. fumigatus.