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A. terreus Amphotericin Resistance — SCE Infectious Diseases MCQ

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ModerateFungal InfectionsA. terreus Amphotericin ResistanceSCE Infectious Diseases

A 40-year-old woman develops Aspergillus terreus invasive aspergillosis. Standard susceptibility testing confirms Amphotericin B resistance (MIC >2 mg/L) but Voriconazole susceptibility. Why is this clinically important?

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Correct answer: C — A. terreus is intrinsically resistant to Amphotericin B — Voriconazole (or Isavuconazole) must be used as first-line; Amphotericin B should NOT be used for A. terreus infections

B. terreus is one of the few Aspergillus species with intrinsic resistance to Amphotericin B (MIC typically >2 mg/L). This is clinically significant because Amphotericin B (including liposomal formulation) is a common empirical choice for invasive aspergillosis. Species identification is therefore critical — if A. terreus is identified, treatment must be Voriconazole or Isavuconazole (first-line azoles that retain full activity). MALDI-TOF MS has improved rapid Aspergillus species identification. A. nidulans and A. lentulus also show reduced Amphotericin B susceptibility.

Reference: IDSA 2016 – Aspergillosis; BSAC 2024 – Antifungal guidelines; EUCAST 2024