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 34-year-old man who works in a wool factory presents to the emergency room with a boil-like black ulcer which developed on his neck over the past 2 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::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::Bacillus anthracis is a gram positive rod, whose lipoteichoic acid stimulates IL-1 and TNF.]]
Answer C	AnswerC::Lipid A
Answer C Explanation	[[AnswerCExp::Lipid A is a molecule found on the outer membrane of gram negative bacteria. It induces 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::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::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. Most people who get sick from anthrax are exposed while working with infected animals or animal products such as wool, hides, or hair. - Inhalation anthrax can occur when a person inhales spores that are in the air (aerosolized) during the industrial processing of contaminated materials, such as wool, hides, or hair. Inhalation anthrax has alternatively been called ‘Woolsorter’s Disease’. - Cutaneous anthrax can occur when workers who handle contaminated animal products get spores in a cut or scrape on their skin. In this case, the patient has contracted Cutaneous anthrax. The lesion is usually a black eschar. When anthrax spores get into the skin, usually through a cut or scrape, a person can develop cutaneous anthrax. This can happen when a person handles infected animals or contaminated animal products like wool, hides, or hair. Cutaneous anthrax is most common on the head, neck, forearms, and hands. It affects the skin and tissue around the site of infection. Cutaneous anthrax is the most common form of anthrax infection, and it is also considered to be the least dangerous. Infection usually develops from 1 to 7 days after exposure. Without treatment, up to 20% of people with cutaneous anthrax may die. However, with proper treatment, almost all patients with cutaneous anthrax survive. Educational Objective: Bacillus anthracis is a gram positive rod, whose lipoteichoic acid stimulates IL-1 and TNF. References: First Aid 2014 page 133 First Aid 2012 page 146.]]
Approved	Approved::Yes
Keyword	WBRKeyword::Microbiology, WBRKeyword::Bacteria, WBRKeyword::Anthrax, WBRKeyword::Inflammation, WBRKeyword::Immune
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::