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Difficulty: HardInfectious Diseases

A 48-year-old man is brought to the emergency department by his wife due to a severe headache, fever, and confusion that began 24 hours ago. His temperature is 39.1°C (102.4°F), blood pressure is 142/86 mmHg, pulse is 110/min, and respirations are 18/min. Physical examination reveals nuchal rigidity. Neurologic examination shows a new-onset right-sided facial droop and right upper extremity weakness. Suspecting acute bacterial meningitis, the physician prepares to initiate the management workup. Arrange the following steps in the most appropriate chronological order of execution.

  1. 1Obtain blood cultures
  2. 2Administer intravenous dexamethasone and empiric antibiotics
  3. 3Perform a non-contrast CT scan of the head
  4. 4Perform a lumbar puncture

Answer

The correct sequence is: Obtain blood cultures, administer intravenous dexamethasone and empiric antibiotics, perform a non-contrast CT scan of the head, and finally perform a lumbar puncture.
In patients with suspected acute bacterial meningitis, the standard sequence is to obtain blood cultures, perform a lumbar puncture, and then administer empiric antibiotics. However, if a patient has indications for neuroimaging prior to a lumbar puncture (such as focal neurologic deficits, altered mental status, papilledema, new-onset seizures, immunocompromised state, or history of central nervous system disease), this sequence must be altered. In such cases, blood cultures are drawn immediately, followed rapidly by the administration of empiric intravenous antibiotics and dexamethasone. Antimicrobial therapy should never be delayed for neuroimaging or a lumbar puncture. Once therapy is initiated, a non-contrast CT scan of the head is performed to rule out a mass lesion or significant intracranial pressure elevation. If the CT scan does not show mass effect or midline shift, a lumbar puncture is safely performed to analyze the cerebrospinal fluid.

Step-by-Step Solution

1
Identify the suspected diagnosis and high-risk features.
The patient has signs of acute bacterial meningitis along with a focal neurologic deficit (right-sided weakness and facial droop).
Focal neurologic deficits indicate a potential space-occupying lesion or increased intracranial pressure.
2
Determine the first step in the diagnostic workup.
Blood cultures should be obtained first.
Cultures must be drawn prior to antibiotic administration to ensure the highest likelihood of pathogen identification.
3
Determine the timing of antimicrobial therapy.
Intravenous dexamethasone and empiric antibiotics are administered immediately after blood cultures.
Because the patient requires neuroimaging before a lumbar puncture, antibiotics must not be delayed, as delayed treatment increases mortality.
4
Determine the sequence of the remaining diagnostic procedures.
A non-contrast CT scan of the head is performed, followed by a lumbar puncture.
The CT head rules out mass effect to prevent herniation during the lumbar puncture. The lumbar puncture follows immediately if the CT is reassuring.

Key Concept

Management sequence of suspected bacterial meningitis in a patient with indications for neuroimaging prior to lumbar puncture.
Estimated Time:1m 30s
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Topics

Infectious Diseases

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