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Difficulty: HardInfectious Diseases

A 5555-year-old man is brought to the emergency department by his wife due to confusion, high fever, and a severe headache that started 1212 hours ago. His medical history is significant for a deceased-donor renal transplant 22 years ago, for which he takes tacrolimus and mycophenolate mofetil. His temperature is 39.2∘C39.2^\circ\text{C} (102.6∘F102.6^\circ\text{F}), blood pressure is 105/65 mm Hg105/65\text{ mm Hg}, pulse is 115/min115\text{/min}, and respirations are 22/min22\text{/min}. On physical examination, the patient is lethargic but arousable. He has pronounced nuchal rigidity. Neurologic examination reveals left-sided pronator drift and a sluggish left pupillary reflex. Fundoscopy shows bilateral blurring of the optic discs. Arrange the following management steps in the most appropriate chronological order for this patient.

  1. 1Obtain two sets of peripheral blood cultures
  2. 2Administer empiric intravenous antibiotics and dexamethasone
  3. 3Perform a non-contrast computed tomography (CT) scan of the head
  4. 4Perform a lumbar puncture to obtain cerebrospinal fluid

Answer

The correct sequence is: Obtain two sets of peripheral blood cultures, followed immediately by administering empiric intravenous antibiotics and dexamethasone. Next, perform a non-contrast CT scan of the head, and finally perform a lumbar puncture to obtain cerebrospinal fluid.
In a patient presenting with classic signs of acute bacterial meningitis (fever, severe headache, nuchal rigidity, altered mental status), the very first step is to draw blood cultures to identify the pathogen. Because this patient is immunocompromised (history of renal transplant) and exhibits focal neurologic deficits (left-sided pronator drift, sluggish pupil) alongside papilledema, there is a high suspicion for elevated intracranial pressure or an intracranial mass lesion. Therefore, a CT scan of the head is mandatory before performing a lumbar puncture to prevent cerebral herniation. Crucially, empiric antibiotics and adjunctive dexamethasone must never be delayed while awaiting neuroimaging; they should be administered immediately after obtaining blood cultures. Once the CT scan rules out mass effect, the lumbar puncture can be safely performed to obtain cerebrospinal fluid for a definitive diagnosis.

Step-by-Step Solution

1
Identify the clinical syndrome and recognize high-risk features.
The patient has signs of acute bacterial meningitis (fever, nuchal rigidity, headache) combined with red flags for elevated intracranial pressure (ICP): immunocompromised state, altered mental status, papilledema, and focal neurologic deficits (pronator drift).
Identifying these red flags dictates that the standard sequence of 'Lumbar Puncture before antibiotics' must be altered to prevent cerebral herniation.
2
Determine the first intervention.
Obtain peripheral blood cultures.
Blood cultures should always be drawn before antimicrobial administration to prevent sterilization of the blood and ensure pathogen identification.
3
Determine the timing of pharmacotherapy.
Administer empiric antibiotics and dexamethasone immediately.
Because neuroimaging is required prior to the lumbar puncture, diagnostic testing will be delayed. Antibiotics must be given immediately after blood cultures are drawn to prevent life-threatening delays in treatment.
4
Determine the correct sequence of diagnostic procedures.
Perform a non-contrast CT scan of the head, followed by a lumbar puncture.
The CT scan is necessary to rule out mass effect or severe elevated ICP. Once cleared, the lumbar puncture can be safely performed to analyze the cerebrospinal fluid.

Key Concept

Management sequence for suspected bacterial meningitis in patients with high-risk features for cerebral herniation.
Estimated Time:2m 0s
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Topics

Infectious Diseases

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