Breakthrough Tracheobronchial Aspergillosis Caused by Aspergillus calidoustus and Aspergillus niger in a Lung Transplant Recipient Despite Combined Antifungal Prophylaxis

Aspergillus niger and Aspergillus calidoustus are relatively uncommon pathogens that could cause invasive disease, especially in immunocompromised patients. We present the case of a 61‐year‐old male with a history of idiopathic pulmonary fibrosis who was admitted to our hospital for a unilateral lung transplant that was performed without complications; despite voriconazole prophylaxis, he developed tracheobronchial aspergillosis, caused by A. niger and A. calidoustus —a species difficult to identify due to its close microbiological and genetic resemblance to other Aspergillus species. Molecular diagnostic methodologies are indispensable for the precise identification of cryptic Aspergillus species, a necessity emphatically demonstrated by this specific clinical presentation. The reliance upon these tools, in contrast to conventional phenotyping, is crucial for guiding appropriate and potentially life‐saving antifungal therapeutic interventions in critical scenarios like lung transplantation.