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Environmental Azole Resistance — SCE Infectious Diseases MCQ

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HardFungal InfectionsEnvironmental Azole ResistanceSCE Infectious Diseases

A 50-year-old man with chronic pulmonary aspergillosis (CPA) on long-term Itraconazole develops progressive disease with new cavitation. Aspergillus fumigatus is cultured from sputum and shows Itraconazole MIC >16 mg/L and Voriconazole MIC 4 mg/L (resistant to both). What environmental factor is increasingly recognised as driving azole resistance in Aspergillus?

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Correct answer: D — Agricultural use of azole fungicides (Tebuconazole, Propiconazole) creating environmental selection pressure for resistant A. fumigatus (TR34/L98H mutation)

Environmental azole resistance in A. fumigatus is an emerging global threat. Agricultural triazole fungicides (sharing the same target — CYP51A — as medical azoles) select for resistant mutations (most commonly TR34/L98H and TR46/Y121F/T289A) in the environment. Humans inhale resistant spores, resulting in azole-resistant invasive aspergillosis from first exposure. This 'environmental route' accounts for the majority of azole resistance in countries like the Netherlands and UK. Alternative agents (Liposomal Amphotericin B) are needed for resistant infections.

Reference: BSAC 2024 – Azole resistance in Aspergillus; ECMM/ISHAM 2024 – Environmental resistance