Review Question - QID 101473

The patient described most likely suffers from mucormycosis, an infection caused by a Mucor or Rhizopus species. These species appear as irregular, non-septate hyphae branching at wide angles.

Patients who are immunosuppressed (organ transplant patients, patients with hematologic cancers, or patients undergoing steroid therapy) are at risk for mucormycosis, as are patients in diabetic ketoacidosis, as the organisms produce ketone reductase, allowing them to thrive in ketotic states. In affected patients, fungi are able to penetrate through the sinuses to the brain, where they may form abscesses. Invasion of blood vessels can additionally cause infarction and necrosis. Treatment for mucormycosis is amphotericin B plus surgical debridement.

Headley reports that, in addition to diabetic ketoacidosis and neutropenia, high-dose corticosteroid therapy and burns can increase the risk of cutaneous mucormycosis-induced necrotizing skin infections, as mucor infections do not only involve deep tissues.

Rammaert et al. report that mucormycosis is a life-threatening invasive fungal infection especially in diabetic patients with or without haematological malignancies or need for solid-organ transplantation. Mucurmycosis primarily affects the rhino-orbito-cerebral arena and is often diagnosed in advanced stages given paucity of clinical signs in early infection.

Illustration A shows a specimen from a patient with mucormycosis revealing irregular, non-septate hyphae branching at wide angles.

Incorrect answers:
Answer 1: Yeast with pseudohyphae is characteristic of Candida.
Answer 2: Budding yeast with a narrow base is characteristic of Cryptococcus.
Answer 3: Septate hyphae branching at acute angles is characteristic of Aspergillus.
Answer 5: Spherules containing endospores is characteristic of Coccidioides.