WBR0052

Author	PageAuthor::William J Gibson
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Genetics, MainCategory::Immunology, MainCategory::Microbiology
Sub Category	SubCategory::Vascular, SubCategory::General Principles, SubCategory::Infectious Disease
Prompt	[[Prompt::A 6 year old African American child is brought to the ER for severe abdominal pain. On examination, his abdomen is stiff and bloated with diffuse pain, but most severe in the upper left quadrant. This is the second such episode for this patient and one of his older sisters suffered a similar disease. After supportive treatment, this patient must receive a vaccine for a certain encapsulated, catalase positive gram negative rod. What moiety is used in this vaccine?]]
Answer A	AnswerA::Polyribosyl Phosphate
Answer A Explanation	AnswerAExp::Correct – See explanation
Answer B	AnswerB::Peptidoglycan
Answer B Explanation	AnswerBExp::Incorrect – Peptidoglycan composes the membrane of most bacteria. It is not used in the Haemophilus Influenza Type B vaccine.
Answer C	AnswerC::Protein A
Answer C Explanation	AnswerCExp::Protein A is a virulence factor of S. Aureus which binds to the Fc portion of Ig and helps to prevent opsonization and phagocytosis. It is not used in the Haemophilus Influenza Type B vaccine.
Answer D	AnswerD::Lipid A
Answer D Explanation	AnswerDExp::Incorrect – Lipid A is a part of endotoxin, a lipopolysaccharide which is a highly immunogenic component of the cell wall of Gram-negative bacteria. It is not used in the Haemophilus Influenza Type B vaccine.
Answer E	AnswerE::M protein
Answer E Explanation	AnswerEExp::Incorrect – M protein is a virulence factor of Strep Pyogenes. M protein helps prevent phagocytosis. It is not used in the Haemophilus Influenza Type B vaccine.
Right Answer	RightAnswer::A
Explanation	[[Explanation:: Educational Objective: References: ]]
Approved	Approved::Yes
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