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Questions and Answers
A patient with a known penicillin allergy requires treatment for a community-acquired pneumonia most likely caused by Mycoplasma pneumoniae. Which of the following macrolides would be most appropriate, considering both spectrum of activity and safety in patients with allergies?
A patient with a known penicillin allergy requires treatment for a community-acquired pneumonia most likely caused by Mycoplasma pneumoniae. Which of the following macrolides would be most appropriate, considering both spectrum of activity and safety in patients with allergies?
- A combination of erythromycin and clarithromycin, to broaden the spectrum of coverage and minimize resistance.
- Erythromycin, due to its established safety profile and broad availability.
- Azithromycin, given its efficacy against atypical organisms and suitability for penicillin-allergic patients. (correct)
- Clarithromycin, for its targeted action against gram-positive bacteria and minimal side effect profile.
A patient develops torsade de pointes while being treated with erythromycin for a Bordetella pertussis infection. Which of the following factors would MOST likely contribute to this adverse effect?
A patient develops torsade de pointes while being treated with erythromycin for a Bordetella pertussis infection. Which of the following factors would MOST likely contribute to this adverse effect?
- Pre-existing condition causing a shortened QT interval, paradoxically increasing arrhythmia risk.
- Genetic predisposition to rapid erythromycin metabolism, reducing the drug's therapeutic effect.
- Concurrent use of a drug that inhibits cytochrome P450 enzymes, leading to increased erythromycin metabolism.
- Concomitant administration of another medication known to prolong the QT interval, increasing the risk of arrhythmia. (correct)
A researcher is investigating the mechanism of action of macrolide antibiotics. If the researcher observes that a bacterial cell is unable to translocate the nascent peptide chain from the A site to the P site on the ribosome, which step is being inhibited by the macrolide?
A researcher is investigating the mechanism of action of macrolide antibiotics. If the researcher observes that a bacterial cell is unable to translocate the nascent peptide chain from the A site to the P site on the ribosome, which step is being inhibited by the macrolide?
- Interference with mRNA binding to the ribosome.
- Inhibition of tRNA binding to the A site.
- Blocking the exit of the peptide chain, thereby inhibiting the translocation step. (correct)
- Prevention of peptide bond formation between amino acids.
A patient on warfarin therapy is prescribed clarithromycin for a respiratory infection. Which of the following potential interactions should be closely monitored, and why?
A patient on warfarin therapy is prescribed clarithromycin for a respiratory infection. Which of the following potential interactions should be closely monitored, and why?
A microbiologist is studying a strain of Streptococcus pneumoniae that exhibits resistance to erythromycin. What is the MOST probable mechanism of resistance in this bacterial strain?
A microbiologist is studying a strain of Streptococcus pneumoniae that exhibits resistance to erythromycin. What is the MOST probable mechanism of resistance in this bacterial strain?
A woman in her second trimester of pregnancy presents with a confirmed Chlamydia pneumoniae infection. Considering the special uses of macrolides, which of the following would be the MOST appropriate antibiotic to prescribe?
A woman in her second trimester of pregnancy presents with a confirmed Chlamydia pneumoniae infection. Considering the special uses of macrolides, which of the following would be the MOST appropriate antibiotic to prescribe?
A patient with diabetic gastroparesis requires a medication to improve gastric motility. Considering the special uses of macrolides, which of the following would be most appropriate?
A patient with diabetic gastroparesis requires a medication to improve gastric motility. Considering the special uses of macrolides, which of the following would be most appropriate?
A patient taking digoxin develops nausea, vomiting, and visual disturbances after being prescribed a macrolide antibiotic. Which macrolide drug interaction is MOST likely responsible for these symptoms?
A patient taking digoxin develops nausea, vomiting, and visual disturbances after being prescribed a macrolide antibiotic. Which macrolide drug interaction is MOST likely responsible for these symptoms?
After initiating clarithromycin, a patient reports new onset jaundice, abdominal pain, and fatigue. Lab results show elevated bilirubin and liver enzymes. Which of the following adverse effects is MOST likely occurring?
After initiating clarithromycin, a patient reports new onset jaundice, abdominal pain, and fatigue. Lab results show elevated bilirubin and liver enzymes. Which of the following adverse effects is MOST likely occurring?
A patient with a history of multiple drug allergies, including a severe reaction to penicillin, requires antibiotic therapy for a confirmed Legionella infection. Which of the following represents the MOST appropriate approach to antibiotic selection?
A patient with a history of multiple drug allergies, including a severe reaction to penicillin, requires antibiotic therapy for a confirmed Legionella infection. Which of the following represents the MOST appropriate approach to antibiotic selection?
Flashcards
Macrolides
Macrolides
Erythromycin, clarithromycin, and azithromycin
Macrolides Mechanism
Macrolides Mechanism
They inhibit translocation and block peptide chain exit, preventing the nascent peptide chain from moving from the A site to the P site
Macrolides Spectrum
Macrolides Spectrum
Gram-positive bacteria (Streptococcus, MSSA), atypical organisms (Chlamydia pneumoniae, Legionella, Mycoplasma pneumoniae), and some mycobacteria
Macrolides Special Uses
Macrolides Special Uses
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Macrolide Resistance
Macrolide Resistance
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Macrolides Side Effects
Macrolides Side Effects
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Macrolides Suffix
Macrolides Suffix
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Study Notes
- Macrolides include antibiotics like erythromycin, clarithromycin, and azithromycin.
- Macrolides inhibit the translocation step by blocking peptide chain exit.
- This causes the nascent peptide chain at the A site to fail to move to the P site.
- Macrolides are bacteriostatic.
- Macrolides' spectrum of activity includes gram-positives like Streptococcus and MSSA.
- They are effective against atypical organisms like Chlamydia pneumoniae, Legionella, and Mycoplasma pneumoniae.
- Azithromycin and clarithromycin are active against mycobacteria.
- Macrolides are effective against Bordetella pertussis.
- Azithromycin and clarithromycin are good alternatives for patients allergic to penicillin.
- Azithromycin or erythromycin is preferred in pregnancy.
- Erythromycin can be used to treat diabetic gastroparesis.
- Resistance to macrolides occurs through methylation of the 23S rRNA-binding site.
- Methylation prevents drug binding.
- Side effects include hypersensitivity reactions like nausea, vomiting, and diarrhea.
- Macrolides can cause prolonged QT intervals and increased risk of torsade de pointes when taken with other drugs that prolong QT intervals.
- They can cause gastrointestinal motility issues, acute cholestatic hepatitis, and eosinophilia.
- Clarithromycin and erythromycin inhibit cytochrome P450 metabolism, increasing levels of many drugs.
- Macrolides increase the risk of bleeding with warfarin.
- They may increase the risk of digoxin toxicity.
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