BCPS BCPS Pharmacotherapy of Infectious Diseases 1 — Questions and Answers
Question 1: A patient with a penicillin allergy (anaphylaxis) requires treatment for methicillin-sensitive Staphylococcus aureus (MSSA) bacteremia. Which antibiotic is the preferred alternative?
- Vancomycin
- Cefazolin after graded challenge
- Daptomycin (Correct answer)
- Clindamycin
Correct answer: Daptomycin
Daptomycin is a preferred alternative for MSSA bacteremia in patients with a history of anaphylaxis to penicillin where beta-lactams are contraindicated.
Question 2: Which pharmacokinetic parameter best guides vancomycin dosing optimization to maximize efficacy and minimize nephrotoxicity per current ASHP/IDSA/SIDP guidelines?
- Peak concentration
- Trough concentration alone
- AUC/MIC ratio (24-hour AUC 400–600) (Correct answer)
- Time above MIC
Correct answer: AUC/MIC ratio (24-hour AUC 400–600)
Current guidelines recommend AUC-guided vancomycin monitoring targeting an AUC/MIC of 400–600 mg·h/L to balance efficacy and nephrotoxicity.
Question 3: A patient with a creatinine clearance of 25 mL/min requires treatment for uncomplicated urinary tract infection caused by E. coli. Which agent is contraindicated due to lack of adequate urinary concentrations at this renal function level?
- Trimethoprim-sulfamethoxazole
- Nitrofurantoin (Correct answer)
- Fosfomycin
- Ciprofloxacin
Correct answer: Nitrofurantoin
Nitrofurantoin is contraindicated when CrCl is below 30 mL/min because it fails to achieve therapeutic urinary concentrations and may accumulate to toxic levels.
Question 4: Which antifungal agent is the drug of choice for invasive aspergillosis in an immunocompromised patient according to IDSA guidelines?
- Fluconazole
- Caspofungin
- Voriconazole (Correct answer)
- Amphotericin B deoxycholate
Correct answer: Voriconazole
Voriconazole is the first-line treatment for invasive aspergillosis per IDSA guidelines due to superior efficacy and survival outcomes compared to amphotericin B.
Question 5: A patient is being treated for hospital-acquired pneumonia with a gram-negative organism that tests positive for an extended-spectrum beta-lactamase (ESBL). Which antibiotic class is the preferred treatment?
- Third-generation cephalosporins
- Fluoroquinolones
- Carbapenems (Correct answer)
- Aztreonam monotherapy
Correct answer: Carbapenems
Carbapenems are the drugs of choice for serious ESBL-producing gram-negative infections because ESBLs hydrolyze all penicillins and cephalosporins but not carbapenems.
Question 6: Which HIV antiretroviral drug class acts by inhibiting the integrase enzyme, preventing insertion of viral DNA into the host chromosome?
- Protease inhibitors (PIs)
- Non-nucleoside reverse transcriptase inhibitors (NNRTIs)
- Integrase strand transfer inhibitors (INSTIs) (Correct answer)
- Entry inhibitors
Correct answer: Integrase strand transfer inhibitors (INSTIs)
INSTIs such as dolutegravir and bictegravir inhibit HIV integrase, blocking the strand transfer step that inserts viral cDNA into the host genome.
BCPS BCPS Pharmacotherapy of Infectious Diseases 1
A patient with a penicillin allergy (anaphylaxis) requires treatment for methicillin-sensitive Staphylococcus aureus (MSSA) bacteremia.
Which antibiotic is the preferred alternative?