USMLE

Mucor and Rhizopus

604 views
Fungi
  1. Histoplasma
  2. Blastomyces
  3. Coccidioides
  4. Paracoccidioides
  5. Tinea (Dermatophytes)
  6. Malassezia
  7. Candida albicans
  8. Aspergillis fumigatus
  9. Cryptococcus neoformans
  10. Mucor and Rhizopus
  11. Pneumocystis jirovecii
  12. Sporothrix schenckii

Summary

Mucor and Rhizopus are branching filamentous fungi that exist exclusively as molds. Mucor and Rhizopus have broad ribbon-like non-septate hyphae. that branch at wide angles approaching 90 degrees. Both fungi are naturally found in the environment and enter the body by way of spore inhalation. These are opportunistic infections primarily affecting immunocompromised patients, especially patients with uncontrolled diabetes. A clinical infection with mucor or rhizopus is formally called mucormycosis. This begins as an invasive necrotic infection that affects the paranasal sinus around the nose, progressing to involve the orbits of the eye and the brain. This results in intense facial pain, headache, vision loss, and neurological symptoms in patients. The treatment for mucormycosis includes emergent surgical debridement and intravenous administration of amphotericin B.

Key Points

  • Characteristics
    • Fungus in mold form only
      • Broad (ribbon-like) non-septate hyphae
      • With right-angle (wide-angle) branching
    • Transmission
      • Spores are inhaled
      • Opportunistic infection
        • Affects immunocompromised patients
        • Especially in uncontrolled diabetes
    • Presentation: Mucormycosis
      • Invasive necrotic paranasal sinus infection
        • Classically forms black eschar in nasal cavity
      • Spreads to orbits and brain (rhino-cerebral)
    • Diagnosis
      • Diagnosis is mostly clinical as early treatment is critical
      • Histopathology of mucosal biopsy and culture confirmation
    • Treatment
      • Surgical debridement and Amphotericin B