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|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=This is the mechanism of action of [[aminoglycosides]] used for gram negative rod infections.
|AnswerC=Blocks translocation
|AnswerC=Blocks peptidyltransferase
|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=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.
|AnswerD=Require 02 for uptake;
|AnswerD= Inhibits the translocation of the peptidyl-tRNA
|AnswerDExp=This often corresponds with [[aminoglycosides]] use.
|AnswerDExp=This often corresponds with [[aminoglycosides]] use.
|AnswerE=Inhibit peptidyl-transferase action
|AnswerE=Inhibit peptidyl-transferase action

Revision as of 13:34, 7 July 2014

 
Author [[PageAuthor::Gonzalo A. Romero, M.D. [1] (Reviewed by Alison Leibowitz)]]
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 about her teeth appear abnormally dark. She states that her daughter developed a ring-like rash on her leg after a nature walk, which appeared to be similar to a rash that her 17-year-old son developed following a camping trip. The mother administered her daughter the leftover antibiotics that had been prescribed to her teenage son for his rash. Which of the following mechanisms of action corresponds to the antibiotic most likely provided to the young girl?]]
Answer A AnswerA::Prevents attachment of aminoacyl-tRNA
Answer A Explanation AnswerAExp::See overall explanation
Answer B AnswerB::Inhibits the formation of initiation complex
Answer B Explanation [[AnswerBExp::This is the mechanism of action of aminoglycosides used for gram negative rod infections.]]
Answer C AnswerC::Blocks peptidyltransferase
Answer C Explanation [[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.]]
Answer D AnswerD::Inhibits the translocation of the peptidyl-tRNA
Answer D Explanation [[AnswerDExp::This often corresponds with aminoglycosides use.]]
Answer E AnswerE::Inhibit peptidyl-transferase action
Answer E Explanation [[AnswerEExp::This is the mechanism of action associated with chloramphenicol.]]
Right Answer RightAnswer::A
Explanation [[Explanation::The clinical vignette describes a patient who delivered a child who currently has discolored teeth. She took an antibiotic during pregnancy to treat Lyme’s disease. The treatment of choice of Lyme disease is tetracycline, which is contraindicated in pregnancy due to bone and teeth malformation. Tetracycline, specifically doxycycline inhibits the protein synthesis by binding to the 30s ribosomal subunit and preventing the aminoacyl-tRNA attachment.

Educational Objective: When tetracycline is administered to young children, it is often associated with teeth discoloration (teratogenic)
References: First Aid 2013 Microbiology-Pharmacology chapter.]]

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