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 bilateral weakness and loss of sensation of 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. The only illness he can recall is an episode of nausea, vomiting, and bloody diarrhea 3 months ago, from which he recovered fully without medications. On exam, motor strength is 1/5 in both lower extremities and deep tendon reflexes are impaired. What is the most likely organism responsible for this patient's condition?]]
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 (GBS). This disease usually occurs several weeks after a self-limited abdominal infection. Campylobacter species is one of the most common organisms involved in the development GBS. GBS is a serious neurologic disease, in which the patient must be monitored in an intensive care setting because of its high likelihood for progression to respiratory failure. Mechanical ventilation is eventually required in up to 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 Campylobacter jejuni 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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