WBR0203

Author	[[PageAuthor::Ayokunle Olubaniyi, M.B,B.S [1] (Reviewed by Yazan Daaboul, M.D.)]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Microbiology
Sub Category	SubCategory::Endocrine, SubCategory::Infectious Disease
Prompt	[[Prompt::A 37-year-old diabetic man is brought to the emergency department (ED) in an unconscious state. His wife explains that she found him in the bedroom floor and immediately called EMS. She states that the patient's past medical history is significant for type 1 diabetes mellitus diagnosed at the age of 23 years; and the patient has recently been non-compliant with his insulin injections. In the ED, initial work-up is remarkable for elevated ketone levels in the urine and serum. Arterial blood gases (ABGs) on admission reveal a blood pH = 7.10. The patient is diagnosed with diabetic ketoacidosis and is admitted for appropriate management. On the third day of hospitalization, the patient develops high-grade fever, headache, and eye pain. Examination of the nasal cavity reveals a black necrotic eschar. What are the microscopic characteristics of the organism responsible for this patient's condition?]]
Answer A	AnswerA::Presence of pseudohyphae
Answer A Explanation	AnswerAExp::Presence of pseudohyphae is a feature seen in Candida albicans infection
Answer B	AnswerB::Broad non-septate hyphae with right angled branching
Answer B Explanation	AnswerBExp::Broad non-septate hyphae with right angled branching is a feature seen in mucormycosis
Answer C	AnswerC::Septate hyphae with V-shaped branching
Answer C Explanation	AnswerCExp::Septate hyphae with V-shaped branching is a feature seen in Aspergillus infections.
Answer D	AnswerD::Oval yeast cells within macrophages
Answer D Explanation	AnswerDExp::Oval yeast cells within macrophages is commonly is a feature commonly seen in histoplasmosis.
Answer E	AnswerE::Broad-base budding
Answer E Explanation	AnswerEExp::Broad-base budding is a pathognomonic feature seen in blastomycosis.
Right Answer	RightAnswer::B
Explanation	[[Explanation::Mucormycosis is an opportunistic fungal infection that commonly affects patients with long-standing diabetes mellitus or those with neutropenia and immunosuppression. The disease has many forms, the most common of which are the rhinocerebral form that commonly develops in diabetic patients and the pulmonary/disseminated forms that commonly develop in immunosuppressed patients. . This form is thought to be preferred given the aerobic nature of the fungus. It is thought that the development of mucormycosis infection among diabetics is associated with the combination of hyperglycemia, ketosis, and acidosis. All 3 factors increase the availability of free iron that the fungus needs for growth: hyperglycemia, ketosis, and acidosis, . Mucomycosis is a severe necrotic infection that is characterized by vascular infiltration with thrombosis and fever, headache and facial pain in a diabetic patient with diabetic ketoacidosis is highly suggestive of Mucormycosis – caused by Mucor, Rhizopus and Absidia. Rhizopus has a high affinity for ketones, and the black necrotic eschar in the nasal cavity is a characteristic finding. These fungi show broad non-septate hyphae with right angled branching. Treatment consists of surgical debridement and amphotericin B. Educational Objective: Fever, headache and facial pain in a diabetic patient with an uncontrolled blood sugar is highly suggestive of mucormycosis. It is treated with amphotericin B following a surgical debridement. References: First Aid 2014 page 148]]
Approved	Approved::No
Keyword	WBRKeyword::Diabetic ketoacidosis, WBRKeyword::mucormycosis
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::