Bacterial meningitis: Difference between revisions
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==Background== |
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* Bacterial infection of meninges |
* Bacterial infection of meninges |
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== |
===Microbiology=== |
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* Adults [[CiteRef::thigpen2011ba]] |
* Adults [[CiteRef::thigpen2011ba]] |
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** ''[[Streptococcus pneumoniae]]'' (70%) |
** ''[[Streptococcus pneumoniae]]'' (70%) |
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** Gram-negative bacilli |
** Gram-negative bacilli |
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===Risk factors=== |
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* Immunosuppression |
* Immunosuppression |
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* Diabetes |
* Diabetes |
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* Chronic otitis media |
* Chronic otitis media |
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== Presentation |
==Clinical Presentation== |
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* Typically, an acute onset of headache with fever and vomiting after viral prodrome |
* Typically, an acute onset of headache with fever and vomiting after viral prodrome |
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* Bacterial vs. aseptic/viral meningitis |
* Bacterial vs. aseptic/viral meningitis |
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* Ask about recent travel and sick contacts |
* Ask about recent travel and sick contacts |
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== |
==Investigations== |
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* Lab |
* Lab |
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** CBC with differential |
** CBC with differential |
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** Lumbar puncture after CT head |
** Lumbar puncture after CT head |
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=== |
===CSF Interpretation=== |
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* Gram stain positive |
* Gram stain positive |
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* Glucose <1.0 |
* Glucose <1.0 |
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* PMNs >1180 |
* PMNs >1180 |
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== |
==Management== |
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* Blood cultures before antibiotics |
* Blood cultures before antibiotics |
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* Start empiric antibiotics and dexamethasone |
* Start empiric antibiotics and dexamethasone |
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* Adjust antibiotics based on Gram stain and cultures |
* Adjust antibiotics based on Gram stain and cultures |
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==Complications== |
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* Cerebral edema with raised ICP |
* Cerebral edema with raised ICP |
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* Hydrocephalus |
* Hydrocephalus |
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Revision as of 00:20, 30 June 2020
Background
- Bacterial infection of meninges
Microbiology
- 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
Clinical 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.
