CNS infections

This morning’s lecture at Mass General/Brigham, about CNS infections, was given by Dr. Jay Vyas. A few take-home points (interspersed with my own commentary) if you were unable to attend:


  • The “jolt sign” making the headache worse is not sensitive for CSF pleocytosis.
  • Obtain blood cultures before giving antibiotics and doing a lumbar puncture.
  • A patient with fever, headache, gets an LP and shows WBC 2200, protein 230, glucose 19. What’s the most likely cause?
    • Bacterial meningitis, because CSF<20, CSF protein>200, CSF WBC>2000. This is the “rule of 2’s”
  • Empiric antibiotic choice for bacterial meningitis should be based on the gram stain from the LP.
    • Don’t forget about Listeria!
  • Can vaccinations help prevent meningitis? Yes, for H flu, pneumococus, and meningococcus.
  • Bacterial meningitis patients should go into droplet precautions initially, because of meningococcus and H flu (I wasn’t aware of the H flu before the lecture).

CNS Shunt infections

  • Infected shunts should be removed, but many patients are shunt dependent.
  • The reservoir should be tapped by the neurosurgical colleagues to send for gram stain and culture
  • Eosinophiia in CSF most commonly represents chronic infection.
  • There are no prospective RCTs of treatment of CNS shunt infections


  • The majority of pathogens we detect are viruses. Some good epidemiological data comes from the California encephalitis project.
  • Bank serum in case you need to do acute/chronic CSF serologies.
  • Neurology will send an anti-NMDA receptor (typically in younger women).
  • MRI is typically done, but brain biopsy is not.
  • We need multiplex PCR assays to speed the diagnosis of multiple viruses.

Brain abscess

  • A lung cancer patient presents with weakness, headache and brain MRI shows a ring enhancing mass. What treatment to give?
    • Ceftriaxone and metronidazole.


  • Genetic testing for 16S rRNA sequencing
  • Next generation sequencing provides independent sequence data from millions of individual DNA molecules, allowing each fragment to be classified independently.
  • Contact
  • Soon we’ll be doing whole genome sequencing routinely in the micro lab.

Thanks so much for reading! Reading/writing blog posts does take significant time and we all know that time is in short supply. You and I will both get much more out of my blog posts if they lead to discussion/dialogue. If you found this post useful and wouldn’t mind leaving a brief comment/sharing on social media, that would be great. Thank so much! Best regards, Phil

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