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Mucorales (Rhizopus / Mucor / Lichtheimia)

Mucor

Morphology: Aseptate (or pauciseptate) hyaline mold with broad, ribbon-like hyphae branching at WIDE (~90°) angles. Distinguishable from Aspergillus by lack of septation.

Mold

Typical drugs

  1. #1Amphotericin B (liposomal)First-line: 5–10 mg/kg/d. SURGICAL DEBRIDEMENT mandatory.
  2. #2IsavuconazoleFDA-approved for mucormycosis; alternative or step-down.
  3. #3PosaconazoleSalvage / step-down; delayed-release tablets preferred.

Empiric therapy when resistant

ALWAYS pair antifungals with aggressive surgical debridement — this is the single most important intervention. Reverse hyperglycemia / DKA. Isavuconazole or posaconazole as step-down.

Resistance mechanisms

  • Target alteration

    INTRINSIC resistance to voriconazole, fluconazole, itraconazole, and echinocandins

    Example: Voriconazole prophylaxis is a classic risk factor for breakthrough mucormycosis.

Resistance notes

INTRINSIC pan-azole resistance except isavuconazole and posaconazole. INTRINSIC echinocandin resistance. Voriconazole-selected breakthrough is a hallmark presentation in heme/onc.

Pearls

Risk factors: uncontrolled diabetes (esp. DKA — iron-loaded environment), iron overload (deferoxamine), hematologic malignancy, voriconazole prophylaxis breakthrough, COVID-associated mucormycosis (CAM, India). Rhino-orbital-cerebral / pulmonary / cutaneous (post-trauma) / GI / disseminated. Time-sensitive: every hour of delay increases mortality. Surgery + amphotericin + reverse predisposing factors = the pillars.

References

  • ESCMID-ECMM Mucormycosis Guidelines (2019)