250.2 📚 國考版

250.2.0.1 必背 — Pathogens

  • Mucorales order: Rhizopus (#1), Mucor, Lichtheimia, Rhizomucor
  • Aseptate broad ribbon-like hyphae with 90° branching on histology

250.2.0.2 必背 — Risk Factors

  • DM (especially DKA) — classic
  • Iron overload + deferoxamine (deferoxamine makes iron available)
  • Immunocompromise (neutropenic, HSCT, transplant, anti-TNF)
  • High-dose corticosteroids
  • COVID-19 + steroid use (India 2021 epidemic)
  • Burns + trauma
  • Voriconazole prophylaxis (selection)

250.2.0.3 必背 — Clinical Forms

  • Rhinocerebral (DKA classic): black eschar on palate + sinus + orbit + brain extension
  • Pulmonary (neutropenic + HSCT): cavitary + halo/reverse halo CT signs
  • Cutaneous (trauma, burns)
  • GI (rare; neonatal + malnourished; high mortality)
  • Disseminated

250.2.0.4 必背 — Diagnosis

  • Clinical + imaging + histology
  • Biopsy: aseptate broad ribbon-like hyphae with 90° branching (PAS/GMS stain)
  • Don’t grind tissue for culture (decreases yield)
  • Black eschar on palate / nasal cavity in DKA

250.2.0.5 必背 — Treatment

  1. Liposomal Amphotericin B 5-10 mg/kg/d (high-dose) — drug of choice
  2. EMERGENT surgical debridement
  3. Reverse predisposing factors (DM control, stop deferoxamine, reduce immunosuppression)
  4. Step-down: isavuconazole or posaconazole PO consolidation × months

250.2.0.6 必背 — Drugs

  • Liposomal AmB = first-line
  • Isavuconazole = FDA 2015 for mucor (oral / IV)
  • Posaconazole delayed-release tablet alternative
  • Echinocandins NOT active (Mucor has no glucan target)
  • Voriconazole NOT active + may select for mucor

250.2.0.7 必背 — Iron Chelation Switch

  • Deferoxamine = bad (makes iron available to mucor)
  • Switch to deferiprone or deferasirox if iron chelation needed (different mechanism)

250.2.0.8 必背 — CAM (COVID-Associated Mucormycosis)

  • India 2021 epidemic; > 45,000 cases
  • Severe COVID + DM + steroid use
  • Rhinocerebral form predominant
  • Same treatment principles

250.2.0.9 必背 — Hyphae Comparison

  • Aspergillus: septate, 45° branching, 3-5 µm
  • Mucor: aseptate (or sparse), 90° branching, broad ribbon-like (5-25 µm)
  • Candida: budding yeast + pseudohyphae