Bacterial Meningitis

Today we discussed the approach to the diagnosis and management of bacterial meningitis.


For a good general review of bacterial meningitis, read the NEJM review by van de Beek et al. The Infectious Diseases Society of America also provides Clinical Practice Guidelines.

I've focused the discussion here on a few evidence based points that were discussed this morning.

(1) Pre-treatment with antibiotics prior to lumbar puncture may cause the culture to become negative, but should not change the biochemical properties of the CSF. This was shown in a study published by Schaad et al comparing ceftriaxone to cefuroxime where repeat lumbar punctures were done at 24 hours post initiation of antibiotics and were found to be unchanged in terms of WBC count, protein and glucose. Based partly on this data, guidelines recommend that if the patient requires a CT scan prior to LP, antibiotics should be given after blood cultures have been drawn, but prior to CT or lumbar puncture.

(2) Concurrent administration of dexamethasone with or prior to the first dose of antibiotics reduces mortality. This difference was shown in a 2002 study published in the NEJM. In this study of a combined group of patients with both streptococcus pneumoniae and with neisseria meningitidis, although the difference was largely evident in the s. pneumoniae group. The dose of dexamethasone used was 10 mg Q6H and this is the current standard of care.

(3) As shown in this brief report, re-insertion of the stylet post lumbar puncture decreases the risk of post-LP headache.

(4) Which patients need a CT brain prior to lumbar puncture? Although the vast majority of CTs done in these patients are normal, the IDSA guidelines recommend CT for anyone with an altered LOC, focal neurologic deficits, papilledema, an immunocompromised state, history of CNS disease or new onset seizure. I've linked the NEJM article supporting these guidelines here.