WBR0050

Author	PageAuthor::William J Gibson
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Microbiology
Sub Category	SubCategory::Pulmonology, SubCategory::General Principles, SubCategory::Infectious Disease
Prompt	[[Prompt::A 52 year old alcoholic and homeless male presents to the ER after coughing blood. He has experienced increasing cough over the past 2 weeks after recovering from an Upper Respiratory Tract Infection. His temperature is 101.5F and a chest X-ray reveals a right upper lobe opacity with right sided hilar adenopathy. Which of the following media could be used to isolate the causal organism?]]
Answer A	AnswerA::Eaton's Agar
Answer A Explanation	AnswerAExp::Incorrect - Eaton’s agar can be used to culture mycoplasma pneumonia.
Answer B	AnswerB::Charcoal Yeast Extract
Answer B Explanation	AnswerBExp::Incorrect - Charcoal Yeast Extract can be used to culture Legionella Pneumophila.
Answer C	AnswerC::Maconkey’s Agar
Answer C Explanation	AnswerCExp::Incorrect - Maconkey’s agar is used to culture a variety of organisms.
Answer D	AnswerD::Tellurite Agar
Answer D Explanation	AnswerDExp::Incorrect - Tellurite agar can be use to culture Corynebacterium Diptheria.
Answer E	AnswerE::Lowenstein-Jensen
Answer E Explanation	AnswerEExp::Correct - Lowenstein-Jensen agar can be used to culture Mycobacterium tuberculosis. See Explanation
Right Answer	RightAnswer::E
Explanation	[[Explanation::The patient in this vignette is suffering from tuberculosis. He has several risk factors for TB including homelessness and alcoholism. Some other infections such as Klebsiella are known for causing pneumonia in alcoholics, typically due to aspiration of oral flora. However, these infections typically cause lower lobe consolidation. Conversely, reactivation mycobacterium prefers to grow in the highly oxygenated upper lobes of the lung and is often accompanied by unilateral enlargement of the hilar lymph nodes. Educational Objective: Mycobacterium tuberculosis can cause reactivation TB in alcoholics and can be cultured on Lowenstein-Jensen agar. Tags: #Microbiology #Biochemistry� Educational Objective: References: ]]
Approved	Approved::Yes
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