Allergic bronchopulmonary aspergillosis (ABPA) is most commonly associated with which organism?

• A. Aspergillus flavus
• B. Mucor species
• C. Candida albicans
• D. Aspergillus fumigatus

Answer: (D)

Allergic bronchopulmonary aspergillosis is a hypersensitivity reaction to inhaled fungi colonizing the airways, most commonly caused by Aspergillus fumigatus. This species is particularly linked to ABPA because its spores easily reach the bronchi and it frequently establishes airway colonization in atopic individuals such as those with asthma or cystic fibrosis, triggering IgE- and immune-complex–mediated inflammation. The result is allergic airway disease with mucus plugging and often central bronchiectasis. Other fungi listed can cause other infections (Mucorales with invasive disease, Candida albicans with mucosal or bloodstream infections, and Aspergillus flavus causing various aspergillosis forms), but ABPA is classically associated with Aspergillus fumigatus.