Critical Care Medicine-Infections and Immunologic Disease>>>>>CNS Infections
Question 1#

A 55-year-old man with a history of well-controlled diabetes and hypertension presents to the emergency department (ED) with a 5- day history of worsening headache and fever. He requests that the light in his room to be turned off as it worsens his headache. Review of systems is otherwise significant only for cough productive of clear phlegm for the last 1 week and intermittent dizziness for 24 hours before presentation. His vital signs are:

He is alert and oriented to time, place, and person. Systemic examination, including a detailed neurological examination, is normal except for a 2/6 ejection systolic murmur in the aortic region and mild nuchal rigidity. Kernig signs are positive. Diagnostic lumbar puncture (LP) is planned.

Which of the following sequences of diagnostic and therapeutic steps is MOST appropriate for the care of this patient? 

A. Blood culture, empiric antibiotics, LP, transfer to intensive care unit (ICU), computed tomography (CT) head with contrast
B. Blood cultures, CT head without contrast, steroids, empiric antibiotics, LP
C. Blood cultures, LP, steroids, empiric antibiotic therapy
D. CT head without contrast, blood cultures, LP, empiric antibiotics, steroids
E. Blood cultures, LP, empiric antibiotic therapy, steroids, magnetic resonance imaging (MRI) of brain with gadolinium

Correct Answer is C


Correct Answer: C

There are multiple factors that determine the optimal sequence of events in cases of suspected community-acquired meningitis. In an ideal scenario without any absolute indication for head imaging, a patient with suspected bacterial meningitis has blood cultures drawn, LP performed, and consideration for steroid therapy in quick succession before timely initiation of appropriate empiric antimicrobial therapy.

Appropriate empiric antimicrobial therapy should be initiated as soon as possible. A delay in the administration of appropriate antimicrobials for bacterial meningitis by 6 to 8 hours has been associated with an increased fatality risk from <5% to 45% and up to 75% for delay of 8 to 10 hours. If interventions are likely to substantially delay antimicrobial administration, the benefits of such interventions should be carefully weighed against the potential of increased mortality risk associated with delayed antimicrobial administration—if a significant delay is anticipated, antimicrobials should take precedence.

Blood cultures should always be obtained before administration of antimicrobials for any infection where microbiological diagnosis has not been achieved.

A CT head is sometimes obtained before LP to look for signs of increased intracranial pressure that can place a patient at risk of brain herniation from the sudden CSF loss during LP. However, in the absence of an absolute indication, this can inadvertently lead to increased door-toantibiotic time, which in turn affects mortality. Therefore, screening of patients for clinical signs of raised intracranial pressure and factors that are known to predispose to complications of LP is strongly encouraged. The Infectious Diseases Society of America (IDSA) recommends a CT head before performance of LP only in the following circumstances:

When taken together, these criteria have a negative predictive value of 97% and a negative likelihood ratio of 0.1 for an abnormal CT head. Therefore, in the absence of any of the above findings, it is deemed safe to proceed with LP without head imaging.

The administration of steroids before or with empiric antimicrobial therapy in patients with suspected pneumococcal meningitis has been associated with a trend toward lower mortality as well as fewer neurological sequelae, a benefit that is lost if steroids are given after initiation of antimicrobials. If suspicion of pneumococcal meningitis is confirmed by LP, steroid therapy should be continued for 4 days. 


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