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Breakthrough Mucormycosis on Azole — SCE Infectious Diseases MCQ

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HardImmunocompromised HostBreakthrough Mucormycosis on AzoleSCE Infectious Diseases

A 40-year-old man develops febrile neutropenia after chemotherapy for AML. He is on Posaconazole prophylaxis. At day 4 of Piperacillin/Tazobactam, he develops pleuritic chest pain. CT chest shows a wedge-shaped peripheral consolidation. Beta-D-glucan is negative. What diagnosis should be considered?

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Correct answer: E — Pulmonary mucormycosis (breakthrough on azole prophylaxis) — Mucorales are intrinsically resistant to Voriconazole and Posaconazole (at standard doses); beta-D-glucan is negative in Mucorales

Breakthrough IFD on azole prophylaxis with negative beta-D-glucan should raise suspicion for Mucorales (which are intrinsically azole-resistant at achievable concentrations and do NOT produce beta-D-glucan). Galactomannan is also negative (Aspergillus-specific). Treatment: Liposomal Amphotericin B 5–10 mg/kg/day plus urgent surgical assessment. Isavuconazole is the only azole with some Mucorales activity. CT findings of reversed halo sign or wedge-shaped infarction support the diagnosis.

Reference: ECMM/MSG 2019 – Mucormycosis; ECIL-6 2017