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 woman 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::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::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::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::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. In this case, the patient has contracted Cutaneous anthrax.
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. 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 been called ‘Woolsorter’s Disease’. |
| Approved | Approved::Yes |
| Keyword | WBRKeyword::Microbiology, WBRKeyword::Bacteria, WBRKeyword::Anthrax, WBRKeyword::Inflammation, WBRKeyword::Immune |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |