A 38-year-old man with a history of HIV infection presents to the emergency department wit… — USMLE Step 3

A $38$ -year-old man with a history of HIV infection presents to the emergency department with a $2$ -week history of progressively worsening headache, fever, and confusion. He has not taken antiretroviral therapy for the past year. Vital signs are temperature $38.8^\circ\text{C}$ ( $101.8^\circ\text{F}$ ), pulse $105/\text{min}$ , respirations $16/\text{min}$ , and blood pressure $110/70\text{ mmHg}$ . Physical examination shows lethargy, nuchal rigidity, and bilateral papilledema. A head CT scan without contrast reveals no focal lesions, mass effect, or hydrocephalus. Laboratory studies show a CD4 T-lymphocyte count of $45/\text{mm}^3$ and a serum sodium level of $131\text{ mEq/L}$ . Lumbar puncture is performed. Cerebrospinal fluid (CSF) analysis shows an opening pressure of $360\text{ mm H}_2\text{O}$ . CSF leukocyte count is $150/\text{mm}^3$ ( $85\%$ lymphocytes), protein is $120\text{ mg/dL}$ , and glucose is $30\text{ mg/dL}$ . India ink preparation reveals encapsulated yeast cells. Which of the following pharmacologic interventions are indicated as part of this patient's immediate management? (Select all that apply)

Intravenous liposomal amphotericin BAnswer
Oral flucytosineAnswer
C
Intravenous dexamethasone
D
Immediate initiation of antiretroviral therapy
E
Intravenous $3\%$ hypertonic saline

Answer

Intravenous liposomal amphotericin B and oral flucytosine

The combination of intravenous liposomal amphotericin B and oral flucytosine is the gold standard induction therapy for cryptococcal meningitis. This dual fungicidal regimen rapidly sterilizes the cerebrospinal fluid and significantly reduces mortality compared to monotherapy. Treatment typically consists of 2 weeks of induction, followed by oral fluconazole for consolidation and maintenance.

Step-by-Step Solution

Analyze the clinical presentation and cerebrospinal fluid findings.

The patient is an immunocompromised host with a subacute presentation of meningitis, markedly elevated opening pressure, and encapsulated yeast on India ink stain.

To establish the definitive diagnosis of cryptococcal meningitis.

Determine the appropriate induction pharmacotherapy.

A combination of a fungicidal polyene (liposomal amphotericin B) and a nucleoside analogue (flucytosine) is required for induction.

To rapidly sterilize the cerebrospinal fluid and significantly reduce acute mortality.

Evaluate the timing of secondary interventions, such as antiretroviral therapy, corticosteroids, and management of mild hyponatremia.

Antiretroviral therapy must be delayed, corticosteroids should be avoided, and mild hyponatremia should be monitored rather than aggressively corrected with hypertonic fluid.

To avoid severe iatrogenic complications (IRIS, delayed fungal clearance) during the acute phase of illness.

Key Concept

Induction pharmacotherapy for HIV-associated cryptococcal meningitis requires a combination of liposomal amphotericin B and flucytosine, while specifically avoiding early antiretroviral therapy and corticosteroids.

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