A 32 year old man is admitted to hospital with a decreased level of consciousness, fever and neck stiffness.
- What diagnosis are you most worried about?
This patient’s clinical picture suggests acute bacterial meningitis, which needs to be managed promptly. - What diagnostic tests can you do to confirm your diagnosis?
The time to treatment should be as short as possible, and should be administered prior to investigations if highly suspicious for meningitis.
Diagnostic tests include:- Lumbar puncture to analyze CSF and CSF culture and sensitivity.
The following findings support the diagnosis of bacterial meningitis (in up to 10% of patients these findings can be normal):- Leukocyte count ≥ 2000 x 106/L
- CSF glucose level <1.9 mmol/L
- CSF:blood glucose ratio <0.23
- Positive gram stain in the CSF
- CT head: evidence suggests that CT head should only be done if the patient presents with coma, papilledema and/or focal neurological deficits. In such a case, antibiotic therapy should be instituted before a CT head is done, and lumbar puncture should immediately follow the CT head
- Lumbar puncture to analyze CSF and CSF culture and sensitivity.
- What empiric therapy would you start this patient on?
Empiric antibiotics should be aimed at treating the most common pathogens of bacterial meningitis: Streptococcus pneumoniae, Hemophilus influenza, Neissiria meningitides, and Listeria monocytogenes (more common in elderly, immunocompromised or pregnant patients).
Therapy should include ceftriaxone (ceftazidime if suspect Pseudomonas infection), vancomycin (for possible resistant Streptococcus pneumonia), and ampicillin (if considering Listeria).
The patient in this case should receive:- Ceftriaxone 2g IV q12h + vancomycin 1g IV q8h
Dexamethasone can be administered at or prior to the first dose of antibiotic (evidence suggests this reduces morbidity and mortality):
- Dexamethasone 10mg IV q6h x4d
Acyclovir can be added as empiric therapy in case of viral meningitis (patients with viral meningitis typically do not appear as sick, yet present with higher fevers).
Infection prevention and control and infectious diseases should be contacted early on in the management of a patient with meningitis.
Resources
Moayedi Y and Gold WL. Acute bacterial meningitis in adults. CMAJ. 2012, 184:1060. Doi: 10.1503/cmaj.111304.
Quagliarello VJ and Scheld WM. Treatment of bacterial meningitis. N Engl J Med. 1997, 336:708-716.
