WBR0507: Difference between revisions

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|MainCategory=Embryology, Microbiology, Pharmacology
|MainCategory=Embryology, Microbiology, Pharmacology
|SubCategory=Infectious Disease
|SubCategory=Infectious Disease
|Prompt=A 2-year-old girl is brought to the pediatrician because her mother is concerned that her teeth have turned a dark shade of grey  since her last check-up. The mother explains that her daughter has been developing normally, but she recently she started refusing formula. She also reports that approximately 1 month ago, the child had an episode of cough and sore throat for which she gave   Which of the following mechanisms of action corresponds to the antibiotic most likely provided to the young girl?
|Prompt=A 2-year-old girl is brought to the pediatrician because her mother is concerned that her teeth have turned a dark shade of gray since her last check-up. The mother explains that her daughter has been developing normally, but she recently started refusing formula. She also reports that approximately 2 months ago, the child had an episode of cough and sore throat for which she gave her some left-over antibiotics she had at home. Physical exam is unremarkable except for dark gray stains apparent mostly across the front teeth. Which of the following is a property of the drug used in this patient?
|Explanation=In this scenario a 2-year-old patient presents with discolored teeth. Her mother had previously administered her with an antibiotic treat a rash, which was indicative of Lyme’s disease. [[Tetracycline]], used to treat [[Lyme disease]], is not prescribed to young children due to the high risk of bone and teeth malformation. [[Tetracycline]], specifically [[doxycycline]], inhibits protein synthesis by binding to the 30S ribosomal subunit and preventing the attachment of aminoacyl-tRNA.
|AnswerA=Prevents attachment of aminoacyl-tRNA to 30S ribosomal subunit
[[File:BullseyeLymeDiseaseRash.jpg|center|400px|]]
|AnswerAExp=Tetracycline
This image above depicts a "bull's eye" rash, often associated with Lyme disease.
|AnswerA=Prevents attachment of aminoacyl-tRNA
|AnswerAExp=See overall explanation
|AnswerB=Inhibits the formation of initiation complex
|AnswerB=Inhibits the formation of initiation complex
|AnswerBExp=This is the mechanism of action of [[aminoglycosides]] used for gram negative rod infections.
|AnswerBExp=Aminoglycosides
|AnswerC=Inhibits protein synthesis by binding to the 50S ribosomal subunit
|AnswerC=Inhibits protein synthesis by binding to the 50S ribosomal subunit
|AnswerCExp=This is the mechanism of action of [[macrolides]], used to treat atypical pneumonias (Mycoplasma, Chlamydia, Legionella), URiI, STDs, gram-positive cocci (streptococcal infections in patients allergic to penicillin), and Neisseria.
|AnswerCExp=Clindamycin
|AnswerD=Inhibits the translocation of the peptidyl-tRNA
|AnswerD=Inhibits the translocation by binding to the 23S ribosomal subunit
|AnswerDExp=This often corresponds with [[aminoglycosides]] use.
|AnswerDExp=Macrolide
|AnswerE=Inhibits protein elongation by blocking peptidyl-transferase
|AnswerE=Inhibits protein elongation by blocking peptidyl-transferase
|AnswerEExp=This is the mechanism of action associated with [[chloramphenicol]].
|AnswerEExp=Chloram
|EducationalObjectives=When tetracycline is administered to young children, it is often associated with teeth discoloration (teratogenic)
|References=First Aid 2013 Microbiology-Pharmacology chapter.
|RightAnswer=A
|RightAnswer=A
|Approved=Yes
|Approved=Yes
}}
}}

Revision as of 13:43, 28 August 2014
Author [[PageAuthor::Gonzalo A. Romero, M.D. (Reviewed by Alison Leibowitz)(Reviewed by Serge Korjian)]]
Exam Type ExamType::USMLE Step 1
Main Category MainCategory::Embryology, MainCategory::Microbiology, MainCategory::Pharmacology
Sub Category SubCategory::Infectious Disease
Prompt [[Prompt::A 2-year-old girl is brought to the pediatrician because her mother is concerned that her teeth have turned a dark shade of gray since her last check-up. The mother explains that her daughter has been developing normally, but she recently started refusing formula. She also reports that approximately 2 months ago, the child had an episode of cough and sore throat for which she gave her some left-over antibiotics she had at home. Physical exam is unremarkable except for dark gray stains apparent mostly across the front teeth. Which of the following is a property of the drug used in this patient?]]
Answer A AnswerA::Prevents attachment of aminoacyl-tRNA to 30S ribosomal subunit
Answer A Explanation AnswerAExp::Tetracycline
Answer B AnswerB::Inhibits the formation of initiation complex
Answer B Explanation AnswerBExp::Aminoglycosides
Answer C AnswerC::Inhibits protein synthesis by binding to the 50S ribosomal subunit
Answer C Explanation AnswerCExp::Clindamycin
Answer D AnswerD::Inhibits the translocation by binding to the 23S ribosomal subunit
Answer D Explanation AnswerDExp::Macrolide
Answer E AnswerE::Inhibits protein elongation by blocking peptidyl-transferase
Answer E Explanation AnswerEExp::Chloram
Right Answer RightAnswer::A
Explanation [[Explanation::

Educational Objective:
References: ]]

Approved Approved::Yes
Keyword
Linked Question Linked::
Order in Linked Questions LinkedOrder::
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