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{{WBRQuestion
{{WBRQuestion
|QuestionAuthor=Anonymous (Edited by Will Gibson, Alison Leibowitz, and Yazan Daaboul)
|QuestionAuthor=Anonymous (Reviewed by Will Gibson, Alison Leibowitz, and Yazan Daaboul)
|ExamType=USMLE Step 1
|ExamType=USMLE Step 1
|MainCategory=Microbiology
|MainCategory=Microbiology
|SubCategory=Genitourinary, Neurology
|SubCategory=Genitourinary
|MainCategory=Microbiology
|MainCategory=Microbiology
|SubCategory=Genitourinary, Neurology
|SubCategory=Genitourinary
|MainCategory=Microbiology
|MainCategory=Microbiology
|SubCategory=Genitourinary, Neurology
|SubCategory=Genitourinary
|MainCategory=Microbiology
|MainCategory=Microbiology
|MainCategory=Microbiology
|MainCategory=Microbiology
|MainCategory=Microbiology
|MainCategory=Microbiology
|SubCategory=Genitourinary, Neurology
|SubCategory=Genitourinary
|MainCategory=Microbiology
|MainCategory=Microbiology
|SubCategory=Genitourinary, Neurology
|SubCategory=Genitourinary
|MainCategory=Microbiology
|MainCategory=Microbiology
|SubCategory=Genitourinary, Neurology
|SubCategory=Genitourinary
|MainCategory=Microbiology
|MainCategory=Microbiology
|SubCategory=Genitourinary, Neurology
|SubCategory=Genitourinary
|MainCategory=Microbiology
|MainCategory=Microbiology
|SubCategory=Genitourinary
|MainCategory=Microbiology
|MainCategory=Microbiology
|SubCategory=Genitourinary, Neurology
|SubCategory=Genitourinary
|Prompt=A 32-year-old man is brought to the emergency department by his wife for progressive bilateral weakness, loss of sensation and distal paresthesia in his lower extremities over the past 5 days. 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 weeks ago, from which he recovered spontaneously without medications. On exam, motor strength is 1/5 in both lower extremities with loss of deep tendon reflexes. What is the most likely organism responsible for this patient's condition?
|MainCategory=Microbiology
|Explanation=This patient has symptoms and signs consistent with [[Guillain-Barré syndrome]] (GBS). GBS is an autoimmune peripheral neuropathy characterized by an acute areflexic symmetrical ascending flaccid paralysis that usually occurs several weeks after a self-limited upper respiratory tract or abdominal infection. It may also affect cranial nerve-innervated muscles in approximately 50% of patients. It is nowadays considered the most common cause of acute flaccid paralysis. It is a type IV hypersensitivity disorder that results in segmental demyelination and secondary axonal degeneration due to infiltration of T-cells and macrophages, complement activation, and antibody formation against Schwann cells by the process of molecular mimicry.
|MainCategory=Microbiology
|SubCategory=Genitourinary
|Prompt=A 32-year-old man is brought to the emergency department by his wife for progressive bilateral weakness, loss of sensation, and distal paresthesias in his lower extremities over the past 5 days. The patient can no longer walk and must be carried onto the examination bed. He denies any recent history of trauma. The only illness he can recall is an episode of nausea, vomiting, and bloody diarrhea 3 weeks ago, from which he recovered spontaneously without medications. Neurological examination is remarkable for a motor strength of 1/5 in both lower extremities with loss of deep tendon reflexes. What is the most likely organism responsible for this patient's condition?
|Explanation=This patient has symptoms and signs consistent with [[Guillain-Barré syndrome]] (GBS). GBS is an autoimmune peripheral neuropathy characterized by an acute areflexic symmetrical ascending flaccid paralysis that usually occurs several weeks following a self-limited upper respiratory tract or abdominal infection. GBS may also affect the cranial nerves in approximately 50% of patients. With the eradication of poliovirus in the developed world, GBS is currently the most common cause of acute flaccid paralysis. It is a type IV hypersensitivity disorder that results in segmental demyelination and secondary axonal degeneration due to infiltration of T-cells and macrophages, complement activation, and antibody formation against Schwann cells by the process of molecular mimicry.


It is a neurological emergency, in which the patient must be monitored in an intensive care setting because of its high likelihood of autonomic dysfunction, such as bradycardia, wide swings in blood pressure, and pogression to diaphragmatic paralaysis and respiratory failure. Mechanical ventilation is eventually required in up to 30% of patients. Although generally regarded to have a good prognosis, approximately 20% of patients suffer permanent disability, and approximately 5% die despite appropriate therapy. Most patients recover spontaneously from the disease. Miller Fisher syndrome is an important variant of GBS; it is characterized by the presence of ophthalmoplegia, ataxia, and areflexia.  
GBS is a neurological emergency, in which the patient must be monitored in an intensive care setting because of its high likelihood of autonomic dysfunction (bradycardia, wide swings in blood pressure, and progression to diaphragmatic paralysis and respiratory failure). Mechanical ventilation is eventually required in up to 30% of patients. Although generally regarded to have a good prognosis, approximately 20% of patients suffer permanent disability, and approximately 5% die despite appropriate therapy. The majority of patients recover spontaneously from the disease. Miller Fisher syndrome is an important variant of GBS; it is characterized by the presence of ophthalmoplegia, ataxia, and areflexia.  


Diagnosis is often suspected by the presence of symptoms and signs, and is confirmed by nerve conduction studies. In suspected cases of GBS, a lumbar puncture is frequently performed to rule out infectious etiologies of neuropathies. Classically, the lumbar puncture among GBS patients reveals albuminocytologic dissociation that is found in approximately half of patients within the first week of illness. In addition to respiratory support, immunotherapy by plasma exchange or IVIg is required. The use of steroids is not effective.  
Diagnosis of GBS is often suspected by the presence of symptoms and signs and is confirmed by nerve conduction studies. In suspected cases of GBS, a lumbar puncture is typically performed to rule out infectious etiologies of neuropathies. Classically, the lumbar puncture among GBS patients reveals albumino-cytologic dissociation, which is evident in approximately half of patients within the first week of illness. In addition to respiratory support, plasma exchange or immunotherapy by IVIg is often required to hasten recovery. The use of steroids is not effective.  


''Campylobacter'' species is one of the most common organisms associated with GBS. ''Campylobacter jejuni'' is a comma-shaped gram-negative oxidase-positive rod that is considered a major cause of infectious bloody diarrhea. It is transmitted by the fecal-oral route.  Spoiled poultry, meat, and unpasteurized milk are common sources of ''Campylobacter jejuni'' gastrointestinal infection. ''Campylobacter jejuni'' is known for its ability to grow at 42<sup>o</sup>C. Other less common infectious agents associated with GBS include CMV, EBV, VZV, and ''Mycoplasma pneumoniae''
''Campylobacter'' species is the most common infectious organism that is associated with the development of GBS. ''Campylobacter jejuni'' is a comma-shaped, gram-negative, oxidase-positive rod that is considered a major cause of infectious bloody diarrhea. It is transmitted by the fecal-oral route.  Spoiled poultry, meat, and unpasteurized milk are also common sources of ''Campylobacter jejuni'' gastrointestinal infection. ''Campylobacter jejuni'' has the ability to grow at 42<sup>o</sup>C. Other less common infectious agents associated with the development of GBS include CMV, EBV, VZV, and ''Mycoplasma pneumoniae''.
|AnswerA=''Streptococcus pyogenes''
|AnswerA=''Streptococcus pyogenes''
|AnswerAExp=[[Guillain-Barré syndrome]] is not commonly associated with ''Streptococcus pyogenes''.  ''S. pyogenes'' infection is associated with [[scarlet fever]], [[rheumatic fever]], pharyngitis, and post-infectious glomerulonephritis.
|AnswerAExp=Development of [[Guillain-Barré syndrome]] is not commonly associated with ''Streptococcus pyogenes'' infection.  ''S. pyogenes'' infection is associated with development of [[scarlet fever]], [[rheumatic fever]], pharyngitis, and post-infectious glomerulonephritis.
|AnswerB=''Clostridium'' species
|AnswerB=''Clostridium'' species
|AnswerBExp=''Clostridium'' species include:  
|AnswerBExp=''Clostridium'' species include:  
* ''C. botulinum'' is associated with flaccid paralysis due to toxin. The paralysis is typically described as symmetrical descending paralysis.
* ''C. botulinum'' is associated with the development of flaccid paralysis due to the botulinum toxin. The paralysis is typically described as symmetrical descending paralysis.
* ''C. difficile'' is associated with pseudomembranous colitis
* ''C. difficile'' is associated with the development of pseudomembranous colitis
* ''C. tetani'' is associated with spastic paralysis. Toxin inhibits the release of inhibitory neurotransmitters.
* ''C. tetani'' is associated with the development of spastic paralysis. The tetanospasmin toxin inhibits the release of inhibitory neurotransmitters.


None of these species are commonly associated with the development of [[Guillain-Barré syndrome]].
None of these species is commonly associated with the development of [[Guillain-Barré syndrome]].
|AnswerC=''Staphlococcus aureus''
|AnswerC=''Staphlococcus aureus''
|AnswerCExp=[[Guillain-Barré syndrome]] is not commonly associated with ''[[Staphylococcus aureus]]''. ''S. aureus'' is a gram-positive coccus that is a component of normal skin flora.  However, it commonly causes toxin-induced rapid-onset food poisoning, cellulitis, and pneumonia. Rarer conditions caused by ''S. aureus'' include toxic shock syndrome, and staphylococcal scalded skin syndrome.
|AnswerCExp=Development of [[Guillain-Barré syndrome]] is not commonly associated with ''[[Staphylococcus aureus]]'' infections. ''S. aureus'' is a gram-positive coccus that is a component of the normal skin flora.  However, it commonly causes toxin-induced (rapid-onset) food poisoning, cellulitis, and pneumonia. Rarer diseases caused by ''S. aureus'' include toxic shock syndrome (TSS), and staphylococcal scalded skin syndrome (SSSS).
|AnswerD=''Campylobacter'' species
|AnswerD=''Campylobacter'' species
|AnswerDExp=''[[Campylobacter jejuni]]'' is one of the most common infections associated with [[Guillain-Barré syndrome]].
|AnswerDExp=''[[Campylobacter jejuni]]'' is one of the most common infectious organisms that are associated with the development of [[Guillain-Barré syndrome]].
|AnswerE=''Neisseria meningitidis''
|AnswerE=''Neisseria meningitidis''
|AnswerEExp=''Neisseria meningitidis'' is not associated with the development of [[Guillain-Barré syndrome]].  ''Neisseria meningitidis'' is an encapsulated, gram-negative diplococcus that ferments maltose. ''Neisseria meningitidis'' typically causes meningitis in unvaccinated sexually active adults.
|AnswerEExp=''Neisseria meningitidis'' is not commonly associated with the development of [[Guillain-Barré syndrome]].  ''Neisseria meningitidis'' is an encapsulated, gram-negative diplococcus that typically causes meningitis among unvaccinated sexually active young adults (e.g. college dormitories).
|EducationalObjectives=[[Guillain-Barré syndrome]] (GBS) is an autoimmune peripheral neuropathy characterized by acute-onset ascending flaccid pralysis and distal paresthesias. It commonly follows a self-limited gastrointestinal infection by [[Campylobacter jejuni]].
|EducationalObjectives=[[Guillain-Barré syndrome]] (GBS) is an autoimmune peripheral neuropathy characterized by the development of acute-onset ascending flaccid paralysis and distal paresthesias following a self-limited gastrointestinal infection by ''[[Campylobacter jejuni]]''.
|References=Yuki N, Hartung H. Guillain-Barre syndrome. ''N Engl J Med''. 2012;366:2294-304
|References=Yuki N, Hartung H. Guillain-Barre syndrome. N Engl J Med. 2012;366:2294-304.<br>
First Aid 2014: page 484
First Aid 2014 page 484
First Aid 2013: page 444
|RightAnswer=D
|RightAnswer=D
|WBRKeyword=Neurology, Neuropathy, Paralysis, Hypersensitivity, Autoimmune, mimicry, Schwann, Guillain, Barre, Syndrome, Campylobacter, jejuni, gastroenteritis, bloody, diarrhea
|WBRKeyword=Neurology, Neuropathy, Paralysis, Hypersensitivity, Autoimmune, Mimicry, Schwann, Guillain Barre syndrome, Campylobacter jejuni, Gastroenteritis
|Approved=Yes
|Approved=Yes
}}
}}
{{WBRImage}}
{{WBRImage}}

Latest revision as of 23:02, 27 October 2020

 
Author PageAuthor::Anonymous (Reviewed by Will Gibson, Alison Leibowitz, and Yazan Daaboul)
Exam Type ExamType::USMLE Step 1
Main Category MainCategory::Microbiology
Sub Category SubCategory::Genitourinary
Prompt [[Prompt::A 32-year-old man is brought to the emergency department by his wife for progressive bilateral weakness, loss of sensation, and distal paresthesias in his lower extremities over the past 5 days. The patient can no longer walk and must be carried onto the examination bed. He denies any recent history of trauma. The only illness he can recall is an episode of nausea, vomiting, and bloody diarrhea 3 weeks ago, from which he recovered spontaneously without medications. Neurological examination is remarkable for a motor strength of 1/5 in both lower extremities with loss of deep tendon reflexes. What is the most likely organism responsible for this patient's condition?]]
Answer A AnswerA::''Streptococcus pyogenes''
Answer A Explanation [[AnswerAExp::Development of Guillain-Barré syndrome is not commonly associated with Streptococcus pyogenes infection. S. pyogenes infection is associated with development of scarlet fever, rheumatic fever, pharyngitis, and post-infectious glomerulonephritis.]]
Answer B AnswerB::''Clostridium'' species
Answer B Explanation [[AnswerBExp::Clostridium species include:
  • C. botulinum is associated with the development of flaccid paralysis due to the botulinum toxin. The paralysis is typically described as symmetrical descending paralysis.
  • C. difficile is associated with the development of pseudomembranous colitis
  • C. tetani is associated with the development of spastic paralysis. The tetanospasmin toxin inhibits the release of inhibitory neurotransmitters.

None of these species is commonly associated with the development of Guillain-Barré syndrome.]]

Answer C AnswerC::''Staphlococcus aureus''
Answer C Explanation [[AnswerCExp::Development of Guillain-Barré syndrome is not commonly associated with Staphylococcus aureus infections. S. aureus is a gram-positive coccus that is a component of the normal skin flora. However, it commonly causes toxin-induced (rapid-onset) food poisoning, cellulitis, and pneumonia. Rarer diseases caused by S. aureus include toxic shock syndrome (TSS), and staphylococcal scalded skin syndrome (SSSS).]]
Answer D AnswerD::''Campylobacter'' species
Answer D Explanation [[AnswerDExp::Campylobacter jejuni is one of the most common infectious organisms that are associated with the development of Guillain-Barré syndrome.]]
Answer E AnswerE::''Neisseria meningitidis''
Answer E Explanation [[AnswerEExp::Neisseria meningitidis is not commonly associated with the development of Guillain-Barré syndrome. Neisseria meningitidis is an encapsulated, gram-negative diplococcus that typically causes meningitis among unvaccinated sexually active young adults (e.g. college dormitories).]]
Right Answer RightAnswer::D
Explanation [[Explanation::This patient has symptoms and signs consistent with Guillain-Barré syndrome (GBS). GBS is an autoimmune peripheral neuropathy characterized by an acute areflexic symmetrical ascending flaccid paralysis that usually occurs several weeks following a self-limited upper respiratory tract or abdominal infection. GBS may also affect the cranial nerves in approximately 50% of patients. With the eradication of poliovirus in the developed world, GBS is currently the most common cause of acute flaccid paralysis. It is a type IV hypersensitivity disorder that results in segmental demyelination and secondary axonal degeneration due to infiltration of T-cells and macrophages, complement activation, and antibody formation against Schwann cells by the process of molecular mimicry.

GBS is a neurological emergency, in which the patient must be monitored in an intensive care setting because of its high likelihood of autonomic dysfunction (bradycardia, wide swings in blood pressure, and progression to diaphragmatic paralysis and respiratory failure). Mechanical ventilation is eventually required in up to 30% of patients. Although generally regarded to have a good prognosis, approximately 20% of patients suffer permanent disability, and approximately 5% die despite appropriate therapy. The majority of patients recover spontaneously from the disease. Miller Fisher syndrome is an important variant of GBS; it is characterized by the presence of ophthalmoplegia, ataxia, and areflexia.

Diagnosis of GBS is often suspected by the presence of symptoms and signs and is confirmed by nerve conduction studies. In suspected cases of GBS, a lumbar puncture is typically performed to rule out infectious etiologies of neuropathies. Classically, the lumbar puncture among GBS patients reveals albumino-cytologic dissociation, which is evident in approximately half of patients within the first week of illness. In addition to respiratory support, plasma exchange or immunotherapy by IVIg is often required to hasten recovery. The use of steroids is not effective.

Campylobacter species is the most common infectious organism that is associated with the development of GBS. Campylobacter jejuni is a comma-shaped, gram-negative, oxidase-positive rod that is considered a major cause of infectious bloody diarrhea. It is transmitted by the fecal-oral route. Spoiled poultry, meat, and unpasteurized milk are also common sources of Campylobacter jejuni gastrointestinal infection. Campylobacter jejuni has the ability to grow at 42oC. Other less common infectious agents associated with the development of GBS include CMV, EBV, VZV, and Mycoplasma pneumoniae.
Educational Objective: Guillain-Barré syndrome (GBS) is an autoimmune peripheral neuropathy characterized by the development of acute-onset ascending flaccid paralysis and distal paresthesias following a self-limited gastrointestinal infection by Campylobacter jejuni.
References: Yuki N, Hartung H. Guillain-Barre syndrome. N Engl J Med. 2012;366:2294-304.
First Aid 2014 page 484]]

Approved Approved::Yes
Keyword WBRKeyword::Neurology, WBRKeyword::Neuropathy, WBRKeyword::Paralysis, WBRKeyword::Hypersensitivity, WBRKeyword::Autoimmune, WBRKeyword::Mimicry, WBRKeyword::Schwann, WBRKeyword::Guillain Barre syndrome, WBRKeyword::Campylobacter jejuni, WBRKeyword::Gastroenteritis
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