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{{WBRQuestion
{{WBRQuestion
|QuestionAuthor={{Rim}}
|QuestionAuthor= {{SSK}} (Reviewed by Serge Korjian)
|ExamType=USMLE Step 1
|ExamType=USMLE Step 1
|MainCategory=Microbiology, Pharmacology
|MainCategory=Microbiology, Pharmacology
Line 8: Line 8:
|MainCategory=Microbiology, Pharmacology
|MainCategory=Microbiology, Pharmacology
|SubCategory=Infectious Disease
|SubCategory=Infectious Disease
|MainCategory=Microbiology, Pharmacology
|MainCategory=Microbiology, Pharmacology
|MainCategory=Microbiology, Pharmacology
|MainCategory=Microbiology, Pharmacology
|MainCategory=Microbiology, Pharmacology
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|MainCategory=Microbiology, Pharmacology
|MainCategory=Microbiology, Pharmacology
|SubCategory=Infectious Disease
|SubCategory=Infectious Disease
|Prompt=A pharmaceutical company is trying to develop a new antibiotic to overcome increasing resistance to macrolides. Their rationale is to create an agent that would be co-administered with azithromycin that counteracts the mechanism by which bacteria become resistant to this antibiotic. Which of the following agents would be appropriate to investigate for this purpose?
|Prompt=A pharmaceutical company is manufacturing a novel antibiotic to overcome increasing resistance to macrolides. Its rationale is to create an agent that would be co-administered with azithromycin to counteract the mechanism by which bacteria become resistant to this antibiotic. Which of the following agents would be appropriate to investigate for this purpose?
|Explanation=[[Image:Resistance_mechanisms.png | 700px]]
|Explanation=[[Image:Resistance_mechanisms.png |900px]]
 
 
Macrolides are a class of antibiotic agents that act by inhibiting protein synthesis specifically inhibiting translocation. They bind to the 23S rRNA binding site of the 50S subunit. They are commonly used to treat atypical pneumonias, chlamydia, and non-tuberculous mycobacteria among others. The mechanism of resistance to macrolides is by the methylation of the 23S rRNA binding site. A suggested mechanism to inhibit resistance it to administer an agent to inhibit bacterial methylation enzymes.




Learning Objective: Resistance to macrolides is by methylation of the 23S rRNA binding site.
Macrolides are a class of antibiotic agents that act by inhibiting protein synthesis specifically inhibiting translocation. They bind to the 23S rRNA binding site of the 50S subunit. They are commonly used to treat atypical pneumonias, extra-pulmonary chlamydial infections, and non-tuberculous mycobacteria among other infections. The mechanism of resistance to macrolides is by methylation of the 23S rRNA binding site. A suggested mechanism to inhibit resistance it to administer an agent to inhibit bacterial methylation enzymes.
 
 
References:
Walsh C. Molecular mechanisms that confer antibacterial drug resistance. Nature. 2000;406(6797):775-81.
|AnswerA=RNA methylation inhibitors
|AnswerA=RNA methylation inhibitors
|AnswerAExp=Inhibition of RNA methylation can in theory help decrease resistance to macrolides since it targets the main resistance mechanism.
|AnswerAExp=Inhibition of RNA methylation can, in theory, help decrease resistance to macrolides since it targets the main resistance mechanism.
|AnswerB=Drug acetylation inhibitors
|AnswerB=Drug acetylation inhibitors
|AnswerBExp=Acetylation inhibitors would work more for aminoglycoside resistance but not for macrolides
|AnswerBExp=Inhibition of acetylation targets the main mechanism of aminoglycoside resistance rather than that of macrolides.
|AnswerC=Beta-lactamase inhibitors
|AnswerC=Beta-lactamase inhibitors
|AnswerCExp=Beta-lactamase inhibitors like tazobactam, clavulanic acid, and sulbactam are used with penicillin antibiotics to inhibit destruction of the beta-lactam ring by beta-lactamase producing bacteria.
|AnswerCExp=Beta-lactamase inhibitors like tazobactam, clavulanic acid, and sulbactam are used with penicillin antibiotics to inhibit destruction of the beta-lactam ring by beta-lactamase producing bacteria.
|AnswerD=Drug efflux pump blockers
|AnswerD=Drug efflux pump blockers
|AnswerDExp=Although drug efflux can be seen as a mechanism of resistance to macrolides, it is minor compared to rRNA methylation.  
|AnswerDExp=Although drug efflux can be seen as a mechanism of resistance to macrolides, it is minor compared to rRNA methylation.
|AnswerE=Drug adenylation inhibitors
|AnswerE=Drug adenylation inhibitors
|AnswerEExp=Drug adenylation is also a form of enzymatic modification seen in resistance to aminoglycosides not in macrolides.
|AnswerEExp=Drug adenylation is also a form of enzymatic modification seen in resistance to aminoglycosides not in macrolides.
|EducationalObjectives=Resistance to macrolides is by methylation of the bacterial 23S rRNA binding site.
|References=Wright GD. Resisting resistance: new chemical strategies for battling superbugs. Chem Biol. 2000;7(6):R127-32.<br>
Walsh C. Molecular mechanisms that confer antibacterial drug resistance. Nature. 2000;406(6797):775-81.
|RightAnswer=A
|RightAnswer=A
|WBRKeyword=Antibiotic resistance, Macrolides
|WBRKeyword=Antibiotic resistance, Macrolides, Methylation,
|Approved=No
|Approved=Yes
}}
}}

Latest revision as of 01:18, 28 October 2020
Author [[PageAuthor::Serge Korjian M.D. (Reviewed by Serge Korjian)]]
Exam Type ExamType::USMLE Step 1
Main Category MainCategory::Microbiology, MainCategory::Pharmacology
Sub Category SubCategory::Infectious Disease
Prompt [[Prompt::A pharmaceutical company is manufacturing a novel antibiotic to overcome increasing resistance to macrolides. Its rationale is to create an agent that would be co-administered with azithromycin to counteract the mechanism by which bacteria become resistant to this antibiotic. Which of the following agents would be appropriate to investigate for this purpose?]]
Answer A AnswerA::RNA methylation inhibitors
Answer A Explanation AnswerAExp::Inhibition of RNA methylation can, in theory, help decrease resistance to macrolides since it targets the main resistance mechanism.
Answer B AnswerB::Drug acetylation inhibitors
Answer B Explanation AnswerBExp::Inhibition of acetylation targets the main mechanism of aminoglycoside resistance rather than that of macrolides.
Answer C AnswerC::Beta-lactamase inhibitors
Answer C Explanation AnswerCExp::Beta-lactamase inhibitors like tazobactam, clavulanic acid, and sulbactam are used with penicillin antibiotics to inhibit destruction of the beta-lactam ring by beta-lactamase producing bacteria.
Answer D AnswerD::Drug efflux pump blockers
Answer D Explanation AnswerDExp::Although drug efflux can be seen as a mechanism of resistance to macrolides, it is minor compared to rRNA methylation.
Answer E AnswerE::Drug adenylation inhibitors
Answer E Explanation AnswerEExp::Drug adenylation is also a form of enzymatic modification seen in resistance to aminoglycosides not in macrolides.
Right Answer RightAnswer::A
Explanation [[Explanation::


Macrolides are a class of antibiotic agents that act by inhibiting protein synthesis specifically inhibiting translocation. They bind to the 23S rRNA binding site of the 50S subunit. They are commonly used to treat atypical pneumonias, extra-pulmonary chlamydial infections, and non-tuberculous mycobacteria among other infections. The mechanism of resistance to macrolides is by methylation of the 23S rRNA binding site. A suggested mechanism to inhibit resistance it to administer an agent to inhibit bacterial methylation enzymes.
Educational Objective: Resistance to macrolides is by methylation of the bacterial 23S rRNA binding site.
References: Wright GD. Resisting resistance: new chemical strategies for battling superbugs. Chem Biol. 2000;7(6):R127-32.
Walsh C. Molecular mechanisms that confer antibacterial drug resistance. Nature. 2000;406(6797):775-81.]]

Approved Approved::Yes
Keyword WBRKeyword::Antibiotic resistance, WBRKeyword::Macrolides, WBRKeyword::Methylation
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