WBR0187

Author	PageAuthor::Ogheneochuko Ajari MB.BS., MS
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Microbiology
Sub Category	SubCategory::Infectious Disease
Prompt	[[Prompt::A 25-year old man presented to the emergency department with a 2-day history of headache, confusion and swelling of the face. Tissue biopsy showed a non-septate irregular width hyphae branching at 90-degree angles. What is the likely causative agent of this patient’s condition?]]
Answer A	AnswerA::Candida albicans
Answer A Explanation	AnswerAExp::Candida albicans forms pseudohyphae and true hyphae at 37 degree Celsius in serum with the germ tube test.
Answer B	AnswerB::Aspergillus fumigatus
Answer B Explanation	AnswerBExp::Aspergillus fumigatus is a monomorphic filamentous fungus, dichotomously branching septate hyphae at 45 degrees angle.
Answer C	AnswerC::Blastomyces dermatitidis
Answer C Explanation	AnswerCExp::Blastomyces dermatitidis forms hyphae with nondescript conidia. The tissue form is a broad-based budding yeast.
Answer D	AnswerD::Rhizopus
Answer D Explanation	AnswerDExp::Rhizopus forms broad ribbon-like nonseptate hyphae branching at 90-degree angles.
Answer E	AnswerE::Sporothrix schenckii
Answer E Explanation	AnswerEExp::Sporothrix schenckii is a dimorphic fungus that forms cigar-shaped yeast in tissue
Right Answer	RightAnswer::D
Explanation	[[Explanation::This is a case of zygomycosis aka mucormycosis or phycomycosis, caused by Rhizopus. Other fungal organisms that can cause this infection are Mucor and Absidia. It may arise as a complication in diabetic ketoacidosis or in leukemic patients and it typically presents as a rhinocerebral disease characterized by paranasal swelling, necrotic tissues, hemorrhagic exudates from the nose and eyes and confusion. On tissue biopsy, it shows as broad ribbon-like nonseptate hyphae branching at 90-degree angles. Educational Objective: References: ]]
Approved	Approved::Yes
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