Antimicrobials USMLE Step 1 Practice Question
A 35-year-old man with HIV infection and a CD4 count of 45 cells/μL presents with a 5-day history of fever, severe headache, photophobia, and neck stiffness. Cerebrospinal fluid analysis shows elevated opening pressure, low glucose, elevated protein, and positive India ink stain; culture confirms Cryptococcus neoformans. He is started on amphotericin B deoxycholate 0.7 mg/kg/day plus flucytosine. On hospital day 3, his serum creatinine increases from 1.0 to 3.2 mg/dL, urinalysis reveals muddy brown casts and proteinuria, and urine osmolality is elevated at 850 mOsm/kg. Physical examination shows blood pressure 96/60 mmHg and heart rate 112 bpm. Intravenous hydration with normal saline has been optimized. Which of the following interventions is most appropriate to reduce amphotericin B-induced nephrotoxicity while maintaining adequate antifungal coverage for CNS penetration?
Answer choices
- ASwitch to liposomal amphotericin B at an equivalent doseCorrect answer
- BReduce amphotericin B dose by 50% and add itraconazole for synergy
- CDiscontinue amphotericin B and initiate high-dose fluconazole monotherapy
- DContinue current regimen with addition of sodium bicarbonate to alkalinize urine
- EMaintain amphotericin B deoxycholate but increase saline infusion volume and frequency
- FSwitch to amphotericin B lipid complex and reduce flucytosine dose
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