A 45-year-old man with poorly controlled diabetes mellitus presents with facial pain, black necrotic nasal discharge, periorbital swelling, and proptosis. CT shows invasion of the nasal sinuses and orbit. This presentation is most consistent with rhinocerebral mucormycosis caused by fungi of which order?
- A Eurotiales
- B Hypocreales
- C Mucorales ✓
- D Onygenales
Correct answer: C. Mucorales
Explanation
Rhinocerebral mucormycosis is caused by fungi of the order Mucorales (class Zygomycetes), including Rhizopus, Mucor, and Lichtheimia species. These fungi produce broad, aseptate (ribbon-like) hyphae that invade blood vessels, causing thrombosis and the characteristic black necrosis. Uncontrolled diabetic ketoacidosis provides the acidic, iron-rich environment that promotes growth. Eurotiales includes Aspergillus, Hypocreales includes Fusarium, and Onygenales includes dermatophytes and dimorphic fungi.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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