WBR0235: Difference between revisions

Jump to navigation Jump to search
(Created page with "{{WBRQuestion |QuestionAuthor=William J Gibson |ExamType=USMLE Step 1 |MainCategory=Microbiology, Pharmacology |SubCategory=Neurology, General Principles |MainCategory=Microbi...")
 
No edit summary
Line 8: Line 8:
|MainCategory=Microbiology, Pharmacology
|MainCategory=Microbiology, Pharmacology
|SubCategory=Neurology, General Principles
|SubCategory=Neurology, General Principles
|MainCategory=Microbiology, Pharmacology
|MainCategory=Microbiology, Pharmacology
|MainCategory=Microbiology, Pharmacology
|MainCategory=Microbiology, Pharmacology
|MainCategory=Microbiology, Pharmacology
Line 21: Line 22:
|SubCategory=Neurology, General Principles
|SubCategory=Neurology, General Principles
|Prompt=A 16 year old boy is brought to his pediatrician’s office by his father.  Over the past several days she has noticed that the left side of his face has become less expressive.  He reports some fatigue.  He denies any sick contacts, recent changes in mood or appetite.  He denies any recent travel, except for a camping trip with the local boy scouts approximately 2 months ago.  He is sexually active with one partner.  His cardiovascular and respiratory exam is normal. His neurological exam is significant only for unilateral weakness of the facial muscles on the left side.  What is the mechanism of action of the most appropriate pharmacotherapy for this patient?
|Prompt=A 16 year old boy is brought to his pediatrician’s office by his father.  Over the past several days she has noticed that the left side of his face has become less expressive.  He reports some fatigue.  He denies any sick contacts, recent changes in mood or appetite.  He denies any recent travel, except for a camping trip with the local boy scouts approximately 2 months ago.  He is sexually active with one partner.  His cardiovascular and respiratory exam is normal. His neurological exam is significant only for unilateral weakness of the facial muscles on the left side.  What is the mechanism of action of the most appropriate pharmacotherapy for this patient?
|Explanation=The patient in this vignette is suffering from the disseminated stage of Lyme Disease.  Lyme disease is caused by the organism Borrelia Burgdorferi, a bacteria which is carried by the Ixodes tick.  In its early stages, Lyme disease causes a characteristic “bullseye” rash called erythema chronicum migrans in 80% of patients.  Most patients exhibit flu-like symptoms in the early stages of infection.  The incubation period of Lyme disease can vary greatly, but is typically 1 to 2 weeks.  If untreated, Lyme disease can cause facial palsy and AV nodal block (secondary Lyme disease) progressing to chronic monoarthritis or migratory polyarthritis (tertiary Lyme disease).  Lyme disease is treated with tetracycline antibiotics (eg doxycyline).  Tetracyclines work by blocking entry of aminoacyl tRNAs into the bacterial ribosome, thereby inhibiting protein synthesis.  
|Explanation=The patient in this vignette is suffering from the disseminated stage of Lyme Disease.  Lyme disease is caused by the organism Borrelia Burgdorferi, a bacteria which is carried by the Ixodes tick.  In its early stages, Lyme disease causes a characteristic “bullseye” rash called erythema chronicum migrans in 80% of patients.  Most patients exhibit flu-like symptoms in the early stages of infection.  The incubation period of Lyme disease can vary greatly, but is typically 1 to 2 weeks.  If untreated, Lyme disease can cause facial palsy and AV nodal block (secondary Lyme disease) progressing to chronic monoarthritis or migratory polyarthritis (tertiary Lyme disease).  Lyme disease is treated with tetracycline antibiotics (eg doxycyline).  Tetracyclines work by blocking entry of aminoacyl tRNAs into the bacterial ribosome, thereby inhibiting protein synthesis.  
'''Educational Objective:'''  Lyme disease istreated with tetracycline antibiotics, which function by blocking entry of aminoacyl tRNAs into the bacterial ribosome, thereby inhibiting protein synthesis.
'''References:'''  First Aid 2012 page 165.
|AnswerA=Activates tissue plasminogen
|AnswerA=Activates tissue plasminogen
|AnswerAExp='''Incorrect''' - This is the mechanism of TpA, which can be used to treat stroke or myocardial infarction.  While a stroke may produce unilateral neurologic symptoms, stroke is far less likely than lyme disease in a young patient who has recently gone on a camping trip.
|AnswerAExp=This is the mechanism of TpA, which can be used to treat stroke or myocardial infarction.  While a stroke may produce unilateral neurologic symptoms, stroke is far less likely than lyme disease in a young patient who has recently gone on a camping trip.
 
|AnswerB=Nucleotide analogue
|AnswerB=Nucleotide analogue
|AnswerBExp='''Incorrect''' - This is the mechanism of acyclovir, which is used to inhibit HSV replication.  HSV can cause Bell’s palsy, but it is a less common cause of Bell’s palsy than Lyme disease and suspicion for Lyme disease should be elevated by the patient’s recent camping trip.
|AnswerBExp=This is the mechanism of acyclovir, which is used to inhibit HSV replication.  HSV can cause Bell’s palsy, but it is a less common cause of Bell’s palsy than Lyme disease and suspicion for Lyme disease should be elevated by the patient’s recent camping trip.
|AnswerC=Activates antithrombin III
|AnswerC=Activates antithrombin III
|AnswerCExp='''Incorrect''' - Incorrect this is the mechanism of heparin.  Heparin can be used for stoke, but stroke is far less likely than lyme disease in a young patient who has recently gone on a camping trip.
|AnswerCExp=This is the mechanism of heparin.  Heparin can be used for stoke, but stroke is far less likely than lyme disease in a young patient who has recently gone on a camping trip.
|AnswerD=Inhibits topoisomerase
|AnswerD=Inhibits topoisomerase
|AnswerDExp='''Incorrect''' - This is the mechanism of fluoroquinolones, which are not the treatment of choice for Lyme disease.
|AnswerDExp=This is the mechanism of fluoroquinolones, which are not the treatment of choice for Lyme disease.
|AnswerE=Inhibits aminoacyl tRNA entry into ribosome
|AnswerE=Inhibits aminoacyl tRNA entry into ribosome
|AnswerEExp='''Correct''' - This is the mechanism of tetracycline antibiotics which are the most appropriate pharmacotherapy for Borrelia Burgdorferi infection.
|AnswerEExp=This is the mechanism of tetracycline antibiotics which are the most appropriate pharmacotherapy for Borrelia Burgdorferi infection.
 
|EducationalObjectives=Lyme disease istreated with tetracycline antibiotics, which function by blocking entry of aminoacyl tRNAs into the bacterial ribosome, thereby inhibiting protein synthesis.
|References=First Aid 2014 page 141
|RightAnswer=E
|RightAnswer=E
|WBRKeyword=Lyme disease, Lyme, Borrelia Burgdorferi, Microbiology, Gram negative, Gram-negative, Bacteria, Zoonotic, Antibiotic, Antibiotics
|Approved=Yes
|Approved=Yes
}}
}}

Revision as of 02:20, 11 September 2014

 
Author PageAuthor::William J Gibson
Exam Type ExamType::USMLE Step 1
Main Category MainCategory::Microbiology, MainCategory::Pharmacology
Sub Category SubCategory::Neurology, SubCategory::General Principles
Prompt [[Prompt::A 16 year old boy is brought to his pediatrician’s office by his father. Over the past several days she has noticed that the left side of his face has become less expressive. He reports some fatigue. He denies any sick contacts, recent changes in mood or appetite. He denies any recent travel, except for a camping trip with the local boy scouts approximately 2 months ago. He is sexually active with one partner. His cardiovascular and respiratory exam is normal. His neurological exam is significant only for unilateral weakness of the facial muscles on the left side. What is the mechanism of action of the most appropriate pharmacotherapy for this patient?]]
Answer A AnswerA::Activates tissue plasminogen
Answer A Explanation [[AnswerAExp::This is the mechanism of TpA, which can be used to treat stroke or myocardial infarction. While a stroke may produce unilateral neurologic symptoms, stroke is far less likely than lyme disease in a young patient who has recently gone on a camping trip.]]
Answer B AnswerB::Nucleotide analogue
Answer B Explanation [[AnswerBExp::This is the mechanism of acyclovir, which is used to inhibit HSV replication. HSV can cause Bell’s palsy, but it is a less common cause of Bell’s palsy than Lyme disease and suspicion for Lyme disease should be elevated by the patient’s recent camping trip.]]
Answer C AnswerC::Activates antithrombin III
Answer C Explanation AnswerCExp::This is the mechanism of heparin. Heparin can be used for stoke, but stroke is far less likely than lyme disease in a young patient who has recently gone on a camping trip.
Answer D AnswerD::Inhibits topoisomerase
Answer D Explanation AnswerDExp::This is the mechanism of fluoroquinolones, which are not the treatment of choice for Lyme disease.
Answer E AnswerE::Inhibits aminoacyl tRNA entry into ribosome
Answer E Explanation AnswerEExp::This is the mechanism of tetracycline antibiotics which are the most appropriate pharmacotherapy for Borrelia Burgdorferi infection.
Right Answer RightAnswer::E
Explanation [[Explanation::The patient in this vignette is suffering from the disseminated stage of Lyme Disease. Lyme disease is caused by the organism Borrelia Burgdorferi, a bacteria which is carried by the Ixodes tick. In its early stages, Lyme disease causes a characteristic “bullseye” rash called erythema chronicum migrans in 80% of patients. Most patients exhibit flu-like symptoms in the early stages of infection. The incubation period of Lyme disease can vary greatly, but is typically 1 to 2 weeks. If untreated, Lyme disease can cause facial palsy and AV nodal block (secondary Lyme disease) progressing to chronic monoarthritis or migratory polyarthritis (tertiary Lyme disease). Lyme disease is treated with tetracycline antibiotics (eg doxycyline). Tetracyclines work by blocking entry of aminoacyl tRNAs into the bacterial ribosome, thereby inhibiting protein synthesis.

Educational Objective: Lyme disease istreated with tetracycline antibiotics, which function by blocking entry of aminoacyl tRNAs into the bacterial ribosome, thereby inhibiting protein synthesis.
References: First Aid 2014 page 141]]

Approved Approved::Yes
Keyword WBRKeyword::Lyme disease, WBRKeyword::Lyme, WBRKeyword::Borrelia Burgdorferi, WBRKeyword::Microbiology, WBRKeyword::Gram negative, WBRKeyword::Gram-negative, WBRKeyword::Bacteria, WBRKeyword::Zoonotic, WBRKeyword::Antibiotic, WBRKeyword::Antibiotics
Linked Question Linked::
Order in Linked Questions LinkedOrder::