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| {{WBRQuestion
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| |QuestionAuthor={{Rim}}
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| |ExamType=USMLE Step 1
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| |MainCategory=Pharmacology
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| |SubCategory=General Principles
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| |MainCategory=Pharmacology
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| |SubCategory=General Principles
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| |MainCategory=Pharmacology
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| |SubCategory=General Principles
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| |MainCategory=Pharmacology
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| |MainCategory=Pharmacology
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| |SubCategory=General Principles
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| |MainCategory=Pharmacology
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| |SubCategory=General Principles
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| |MainCategory=Pharmacology
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| |SubCategory=General Principles
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| |MainCategory=Pharmacology
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| |SubCategory=General Principles
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| |MainCategory=Pharmacology
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| |MainCategory=Pharmacology
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| |SubCategory=General Principles
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| |Prompt=A 72 year old male patient presents to the emergency department for high grade fever and altered mental status. Blood cultures grow ESBL-producing E. coli. Based on image shown below, at which specific site on penicillin G does the organism's beta-lactamase act?
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| [[Image:WBR0529.png|650px]]
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| |Explanation=Extended spectrum beta-lactamase (ESBL) producing bacteria, such as E.coli or Klebsiella species, acquire resistance to penicillin and its derivatives by the action of beta-lactamase enzyme which hydrolyzes the beta-lactam ring of the antibiotic and prevents its action. The penicillin G structure is shown in the image above. Beta-lactam is the ring structure that is hydrolyzed by beta-lactamase enzyme
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| Educational Objective: Beta-lactam ring on penicillin G is an important site for resistance by ESBL-producing bacteria.
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| |AnswerA=A
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| |AnswerAExp=This is not the site of beta-lactamase action.
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| |AnswerB=B
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| |AnswerBExp=This is not the site of beta-lactamase action.
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| |AnswerC=C
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| |AnswerCExp=This site on the beta-lactam ring is the site that beta-lactamases use to break down penicillin and thus acquire resistance.
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| |AnswerD=D
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| |AnswerDExp=This is not the site of beta-lactamase action.
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| |AnswerE=E
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| |AnswerEExp=This is not the site of beta-lactamase action.
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| |RightAnswer=C
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| |WBRKeyword=ESBL, producing, bacteria, E. coli, Klebsiella, urosepsis, extended, spectrum, beta-lactamase, penicillin
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| |Approved=No
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| }}
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