Antimicrobial Prescribing Flashcards

A 68-year-old male is prescribed levofloxacin for pneumonia. Which adverse effect should prompt immediate discontinuation and closest monitoring?

Answer: Tendon pain, especially at the Achilles

Fluoroquinolones carry an FDA black box warning for tendinopathy and tendon rupture, particularly the Achilles tendon, and must be stopped immediately if tendon pain occurs.

Which antibiotic carries the highest risk of precipitating Clostridioides difficile infection due to its marked disruption of anaerobic gut flora?

Answer: Clindamycin

Clindamycin has one of the highest risks of C. diff infection among antibiotics because it broadly eliminates anaerobic flora that normally suppress C. difficile colonization.

A patient on azithromycin for atypical pneumonia also takes methadone. What is the primary cardiac concern?

Answer: QT interval prolongation and risk of torsades de pointes

Both azithromycin and methadone can prolong the QT interval; concurrent use significantly raises the risk of fatal torsades de pointes ventricular arrhythmia.

A 7-year-old child with a respiratory infection is prescribed doxycycline. What is the key concern with this prescribing decision?

Answer: Tetracyclines cause permanent tooth discoloration and enamel hypoplasia in children under 8

Tetracyclines, including doxycycline, bind to developing calcified tissues and cause permanent yellow-brown tooth staining and enamel hypoplasia in children under 8 years.

A patient receiving gentamicin develops rising serum creatinine and new-onset tinnitus. What do these findings indicate?

Answer: Aminoglycoside nephrotoxicity and ototoxicity requiring discontinuation

Rising creatinine (nephrotoxicity) and tinnitus (ototoxicity) are classic dose-dependent adverse effects of aminoglycosides and require prompt drug discontinuation.

A patient with a documented penicillin allergy (rash) requires a beta-lactam antibiotic for a serious infection. What is the safest approach?

Answer: Cross-reactivity between penicillins and cephalosporins is primarily due to the R1 side chain; structural dissimilarity makes most cephalosporins safe

Cross-reactivity between penicillins and cephalosporins is due to similar R1 side chains; for non-anaphylactic penicillin allergy, structurally dissimilar cephalosporins can often be used safely.

An immunocompromised patient receiving broad-spectrum antibiotics for 10 days develops oral thrush and is started on fluconazole. Which antibiotic co-administration requires dose adjustment or monitoring due to interaction with fluconazole?

Answer: Rifampin

Rifampin is a potent CYP3A4 inducer that significantly reduces fluconazole plasma concentrations, potentially rendering antifungal therapy ineffective.