Bacterial meningitis: Difference between revisions
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== Etiology == |
== Etiology == |
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| − | * Adults |
+ | * Adults [[CiteRef::thigpen2011ba]] |
| − | ** ''[[Streptococcus pneumoniae]]'' |
+ | ** ''[[Streptococcus pneumoniae]]'' (70%) |
| − | ** ''[[Neisseria meningitidis]]'' |
+ | ** ''[[Neisseria meningitidis]]'' (15%): more in young adults |
| ⚫ | |||
| ⚫ | |||
| − | ** ''[[Haemophilus influenzae]]'' |
+ | ** ''[[Haemophilus influenzae]]'' (10%) |
| ⚫ | |||
| − | * Infants: |
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| + | * Infants ≤2 months old [[CiteRef::thigpen2011ba]] |
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| ⚫ | |||
| + | ** [[Group B Streptococcus]] (90%) |
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| − | ** ''[[Escherichia coli]]'' |
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| + | ** [[Listeria monocytogenes]], [[Streptococcus pneumoniae]], others including Gram-negative bacilli |
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| ⚫ | |||
| + | * Infants 2 months to 2 years [[CiteRef::thigpen2011ba]] |
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| − | ** ''[[Listeria monocytogenes]]'' |
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| + | ** ''[[Streptococcus pneumoniae]]'' (50%) |
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| + | ** [[Group B Streptococcus]] (20%) |
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| + | ** ''[[Neisseria meningitidis]]'' (15%) |
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| ⚫ | |||
* Head trauma or neurosurgery |
* Head trauma or neurosurgery |
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** ''[[Staphylococcus aureus]]'' |
** ''[[Staphylococcus aureus]]'' |
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| − | ** Gram- |
+ | ** Gram-negative bacilli |
== Risk factors == |
== Risk factors == |
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Revision as of 18:31, 2 October 2019
- Bacterial infection of meninges
Etiology
- Adults 1
- Streptococcus pneumoniae (70%)
- Neisseria meningitidis (15%): more in young adults
- Group B Streptococcus (10%)
- Haemophilus influenzae (10%)
- Listeria monocytogenes (5%): more in elderly ≥65 years, immunocompromised, alcoholics, and diabetes
- Infants ≤2 months old 1
- Group B Streptococcus (90%)
- Listeria monocytogenes, Streptococcus pneumoniae, others including Gram-negative bacilli
- Infants 2 months to 2 years 1
- Streptococcus pneumoniae (50%)
- Group B Streptococcus (20%)
- Neisseria meningitidis (15%)
- Haemophilus influenzae (10%)
- Head trauma or neurosurgery
- Staphylococcus aureus
- Gram-negative bacilli
Risk factors
- Immunosuppression
- Diabetes
- Splenic dysfunction or splenectomy (e.g. sickle cell)
- Alcoholism
- Recent neurosurgery
- CSF leak
- Shunt infections
- Head trauma
- Chronic otitis media
Presentation
- Typically, an acute onset of headache with fever and vomiting after viral prodrome
- Bacterial vs. aseptic/viral meningitis
- Headache or neck pain (70-80%)
- Fever (75%)
- Altered level of consciousness (70%)
- Clinical signs
- Brudzinski's sign (unhelpful)
- Kernig's sign (may be specific)
- Jolt test (very sensitive)
- Seizures or focal neurological deficits (rare, poor prognosis)
- Rash (purpuric with Neisseria)
- Ask about recent travel and sick contacts
Investigations
- Lab
- CBC with differential
- Electrolytes
- Liver enzymes
- Blood cultures
- Imaging
- CT head to rule out abscess or increased ICP
- MRI head if suspicion for herpes encephalitis
- Temporal lobe enhancement (usually unilateral)
- Other
- Lumbar puncture after CT head
CSF Interpretation
- Gram stain positive
- Glucose <1.0
- CSF:blood glucose <0.23
- Protein >2.2
- WBC >2000
- PMNs >1180
Management
- Blood cultures before antibiotics
- Start empiric antibiotics and dexamethasone
- Infants
- Children
- Adults
- Ceftriaxone 2g bid
- vancomycin 1g q12h
- +/- ampicillin 2g 14h if >50
- Dexamethasone 10mg q6h x72h
- +/- acyclovir
- >65 years old
- Treat like immunocompromised
- CT head if reduced or altered level of consciousness
- Lumbar puncture
- Adjust antibiotics based on Gram stain and cultures
Complications
- Cerebral edema with raised ICP
- Hydrocephalus
- Seizures
- Arterial ischemia or infarction
- SIADH
- Subdural effusion or subdural empyema
- Venous sinus thrombosis
- Cranial nerve palsies, especially deafness
References
- a b c Michael C. Thigpen, Cynthia G. Whitney, Nancy E. Messonnier, Elizabeth R. Zell, Ruth Lynfield, James L. Hadler, Lee H. Harrison, Monica M. Farley, Arthur Reingold, Nancy M. Bennett, Allen S. Craig, William Schaffner, Ann Thomas, Melissa M. Lewis, Elaine Scallan, Anne Schuchat. Bacterial Meningitis in the United States, 1998–2007. New England Journal of Medicine. 2011;364(21):2016-2025. doi:10.1056/nejmoa1005384.
