WBR0529
| Author | [[PageAuthor::Rim Halaby, M.D. [1]]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Pharmacology |
| Sub Category | SubCategory::General Principles |
| Prompt | [[Prompt::A 72 year old patient presents to the emergency department for high grade fever and altered mental status. His past medical history is significant for a radical prostatectomy several days before presentation. Following appropriate work-up, he is diagnosed with urosepsis. Blood cultures grow ESBL-producing E. coli. Based on image shown below, at which site on penicillin G does the organism's beta-lactamase act?
|
| Answer A | AnswerA::A |
| Answer A Explanation | AnswerAExp::This is not the site of beta-lactamase action. |
| Answer B | AnswerB::B |
| Answer B Explanation | AnswerBExp::This is not the site of beta-lactamase action. |
| Answer C | AnswerC::C |
| Answer C Explanation | AnswerCExp::This site on the beta-lactam ring is the site that beta-lactamases use to break down penicillin and thus acquire resistance. |
| Answer D | AnswerD::D |
| Answer D Explanation | AnswerDExp::This is not the site of beta-lactamase action. |
| Answer E | AnswerE::E |
| Answer E Explanation | AnswerEExp::This is not the site of beta-lactamase action. |
| Right Answer | RightAnswer::C |
| Explanation | [[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
Educational Objective: Beta-lactam ring on penicillin G is an important site for resistance by ESBL-producing bacteria. |
| Approved | Approved::No |
| Keyword | WBRKeyword::ESBL, WBRKeyword::producing, WBRKeyword::bacteria, WBRKeyword::E. coli, WBRKeyword::Klebsiella, WBRKeyword::urosepsis, WBRKeyword::extended, WBRKeyword::spectrum, WBRKeyword::beta-lactamase, WBRKeyword::penicillin |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |
