Tuesday, February 9th, 2010

Microbial Mystery #001

Consider a 21 year-old presenting to the emergency department with fevers and agitation.

His lumbar puncture results are shown below:

Q1. What is the diagnosis?

Show Answer

Meningococcal meningitis

Q2. What is the ‘normal’ ratio of red cells to white cells in the CSF?

500:1 (although this may vary depending on the number of red cells and white cells in the peripheral blood)

Q3. What is the role of steroids in this condition?

Corticosteroid use in Western Countries is supported by evidence from a randomised controlled trial performed in Europe:

The points to note about this trial are:

dexamethasone 10mg QID for 4 days led to a decrease in death and disability in adults treated for bacterial meningitis
dexamethasone was administered 10-15 minutes before or at the time of antibiotics (no-one knows if there is benefit in administering steroids in any way other than this and there may be harm)
the benefit was only demonstrated in patients with pneumococcal meningitis in a setting where resistant pneumococcus was rare (no benefit has been demonstrated in meningococcal meningitis)

Two studies from third world countries have failed to demonstrate a benefit:
http://content.nejm.org/cgi/content/full/357/24/2507