WBR0006

Author	PageAuthor::Anonymous (Edited by Will Gibson and Alison Leibowitz)
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Microbiology
Sub Category	SubCategory::Neurology
Prompt	[[Prompt::A 32-year-old man is brought to the emergency room by his wife for progressive loss of sensation and motor function of both his lower extremities over the past month. The patient can no longer walk and must be carried onto the exam bed. He denies any recent history of trauma and the only illness he can recall consists of an episode of nausea, vomiting, and diarrhea 3 months ago, from which he recovered fully without medications. On exam, motor strength is 1/5 in both legs and deep tendon reflexes are impaired. What is the most likely organism responsible for this illness?]]
Answer A	AnswerA::''Streptococcus pyogenes''
Answer A Explanation	[[AnswerAExp::Guillain-Barré syndrome is not commonly caused by Streptococcus pyogenes. S. pyogenes infection is associated with scarlet fever, rheumatic fever, pharyngitis, as well as many other clinical manifestations.]]
Answer B	AnswerB::''Clostridium'' species
Answer B Explanation	[[AnswerBExp::Clostridium species include: Clostridium botulinum: Associated with laccid paralysis due to toxin Clostridium difficile: Associated with pseudomembranous colitis. Clostridium tetani. Associated with spastic paralysis. Toxin inhibits the release of inhibitory neurotransmitters. None of these species are most commonly associated with the development of Guillain-Barré syndrome.]]
Answer C	AnswerC::''Staphlococcus aureus''
Answer C Explanation	[[AnswerCExp::Guillain-Barré syndrome is not commonly cause by Staphylococcus aureus. S. aureus is a gram positive cocci that is a component of normal skin flora. However, it commonly causes rapid onset food poisoning, cellulitis and pneumonia. Rarer conditions caused by S. aureus include toxic shock syndrome,and scalded skin syndrome.]]
Answer D	AnswerD::''Campylobacter'' species
Answer D Explanation	[[AnswerDExp::Campylobacter jejuni is the most common cause of Guillain-Barré syndrome.]]
Answer E	AnswerE::''Neisseria meningitidis''
Answer E Explanation	[[AnswerEExp::Neisseria meningitidis is not associated with the development of Guillain-Barré syndrome. Neisseria meningitidis is an encapsulated, gram negative diplococcus that ferments maltose (M for maltose in the name). Neisseria meningitidis typically causes meningitis in adults.]]
Right Answer	RightAnswer::D
Explanation	[[Explanation::This patient has symptoms and history suggestive of Guillain-Barré syndrome. This disease usually occurs after a self-limited abdominal infection in which Campylobactor species is involved. Guillain-Barré syndrome (GBS) is a serious neurologic disease, in which the patient must be monitored as an inpatient because of its high likelihood for progression to respiratory failure (mechanical ventilation is required in 30% of patients). GBS is thought to be caused by a Type IV hypersensitivity reaction in which schwann cells are targeted for destruction. Most patients recover spontaneously from the disease. Campylobacter jejuni is a major cause of bloody diarrhea that is often spread through fecal-oral transmission. Spoiled poultry, meat and unpasteurized milk are common sources of gastrointestinal infection. Campylobacter jejuni is known for its ability to grow at 42oC. Educational Objective: Campylobacter jejuni is the most common cause of Guillain-Barré syndrome References: First Aid 2014: page 484 First Aid 2013 page 444]]
Approved	Approved::Yes
Keyword	WBRKeyword::Neurology, WBRKeyword::Neuropathy, WBRKeyword::Paralysis, WBRKeyword::Hypersensitivity, WBRKeyword::Autoimmune, WBRKeyword::Schwann
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::

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