WBR0076

Author	PageAuthor::William J Gibson
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Microbiology, MainCategory::Pathology
Sub Category	SubCategory::Dermatology, SubCategory::General Principles, SubCategory::Infectious Disease
Prompt	Prompt::A patient who works in a wool factory presents to the Emergency Room with a boil-like black ulcer which developed on her forearm over the past 3 days. Which component of the organism causing this disease induces the production of TNF and IL-1?
Answer A	AnswerA::Peptidoglycan
Answer A Explanation	AnswerAExp::'''Incorrect: ''' Peptidoglycan is composed of a sugar backbone with cross-linking by peptide side chains. It provides support for bacterial cells and protects against osmotic forces but does not directly induce IL-1 and TNF.
Answer B	AnswerB::Lipoteichoic acid
Answer B Explanation	AnswerBExp::'''Correct: ''' Cutaneous anthrax is known for causing black eschar lesion. Anthrax is a gram positive rod, whose Lipoteichoic acid stimulates IL-1 and TNF.
Answer C	AnswerC::Lipid A
Answer C Explanation	[[AnswerCExp::Incorrect: Lipid A is a molecule found on the outer membrane of Gram Negative bacteria. It does induce the production of TNF and IL-1, but the bacteria suspected by this clinical presentation is Bacillus Anthracis, a gram-positive organism.]]
Answer D	AnswerD::D-Glutamate Capsule
Answer D Explanation	AnswerDExp::'''Incorrect: '''Bacillus Anthracis is the only organism with a D-Glutamate Capsule. However, it does not induce the production of IL-1 and TNF.
Answer E	AnswerE::Glycocalyx
Answer E Explanation	AnswerEExp::'''Incorrect: '''The glycocalyx mediates bacterial adhesion to structures such as catheters, biological membranes and other surfaces. It does not directly induce IL-1 and TNF.
Right Answer	RightAnswer::B
Explanation	[[Explanation::The patient in this passage has become infected with Bacillus Anthracis, a gram-positive, spore forming rod. In this case, the patient has contracted Cutaneous anthrax. Patients are often exposed to anthrax in the occupations where they come in frequent contact with animals or their products (such as skin, wool and meat). Inhalational anthrax has alternatively called ‘Woolsorter’s Disease’ Educational Objective: Cutaneous anthrax is known for causing black eschar lesion. Anthrax is a gram positive rod, whose Lipoteichoic acid stimulates IL-1 and TNF. References: First Aid 2012 Page 146. Educational Objective: References: ]]
Approved	Approved::Yes
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