Meningitis: Difference between revisions
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== Background ==
==Background==
===Microbiology===
*Inflammation of the meninges (membranes surrounding the brain and spinal cord)
*Bacterial meningitis:
*'''Bacterial meningitis is a medical emergency''' — mortality 15-25% even with treatment; up to 50% untreated<ref>van de Beek D, et al. Community-acquired bacterial meningitis. ''Nat Rev Dis Primers''. 2016;2:16074. PMID 27808261</ref>
**[[Pneumococcus]] (60%), [[meningococcus]] (15%), GBS (15%), [[H flu]] (7%), [[listeria]] (2%)
*Time to antibiotics is the most critical intervention — every hour of delay increases mortality
*Viral meningitis
**Echo, coxsackie, entero (85%)
**[[HSV]], [[CMV]], [[Herpes B virus]]


===Pathophysiology===
===Common Organisms by Age===
*Hematogenous spread via respiratory tract
*Neonates (<1 month): Group B Streptococcus (GBS), ''E. coli'', ''Listeria monocytogenes''
*Contiguous spread ([[otitis media]], [[sinusitis]], [[brain abscess]])
*Infants/Children (1 month - 18 years): ''Neisseria meningitidis'', ''Streptococcus pneumoniae'', ''Haemophilus influenzae'' type b (less common post-vaccination)
*Adults (18-50): S. pneumoniae (most common), N. meningitidis
*Adults >50, immunocompromised, alcoholics: S. pneumoniae, Listeria, gram-negative bacilli
*Post-neurosurgical/VP shunt: ''Staphylococcus'' species, gram-negative bacilli


=== Risk Factors ===
===Viral Meningitis===
{{Meningitis risk factors}}
*Most common cause overall; enterovirus in majority
*Generally self-limited; much better prognosis than bacterial


=== Classification ===
==Clinical Features==
*Acute (<24hr)  
*Classic triad (headache, fever, neck stiffness): present in only ~44% of bacterial meningitis
**Usually bacterial in origin (25%)  
*At least 2 of 4 (headache, fever, neck stiffness, AMS) present in 95%<ref>van de Beek D, et al. Clinical features and prognostic factors in adults with bacterial meningitis. ''N Engl J Med''. 2004;351(18):1849-1859. PMID 15509818</ref>
*Subacute (1-7d)  
*Headache (87%), fever (77%), neck stiffness (83%)
**Viral or bacterial
*'''Altered mental status''' (ranging from confusion to coma)
*Chronic (>7d)  
*Photophobia
**Viral, [[TB]], [[syphilis]], [[fungi]], carcinomatous
*Kernig sign: pain with knee extension when hip is flexed (sensitivity ~5%)
*Brudzinski sign: involuntary hip flexion with passive neck flexion (sensitivity ~5%)
*Jolt accentuation: worsening headache with horizontal head rotation (better sensitivity than Kernig/Brudzinski)
*Petechial/purpuric rash: highly suggestive of N. meningitidis (meningococcemia)
*Neonates: irritability, poor feeding, bulging fontanelle, hypothermia or fever
*Elderly: may present with only confusion without classic features


== Clinical Features ==
==Differential Diagnosis==
Almost all adults present with at least 2 of the following:<ref>van de Beek D. et al. Clinical features and prognostic factors in adults with bacterial meningitis. N Engl J Med. 2004 Oct 28. 351(18):1849-59.</ref>
*[[Subarachnoid hemorrhage]]
*[[Headache]]
*[[Encephalitis]]
*[[Fever]]  
*Brain abscess
*Neck stiffness
*[[Subdural hemorrhage]] / epidural abscess
*[[Altered Mental Status]]
*[[Stroke]]
*Viral meningitis
*Carcinomatous meningitis
*Drug-induced meningitis (NSAIDs, IVIG, TMP-SMX)


Other nonspecific symptoms include:
{{Altered mental status and fever DDX}}
*Photophobia
*Vomiting
*Prodromal URI
*Focal neuro sx (e.g. CN deficit)
*[[Seizures]]


== Differential Diagnosis  ==
==Evaluation==
{{Headache DDX}}
===DO NOT DELAY ANTIBIOTICS FOR LP===
*If LP will be delayed (CT needed, patient unstable): give antibiotics FIRST, then CT, then LP
*Blood cultures should be drawn before antibiotics when possible (do not delay abx for cultures)


{{AMS and fever DDX}}
===Lumbar Puncture===
*CT BEFORE LP only if:
**Immunocompromised, history of CNS disease
**New-onset [[seizures]]
**[[Papilledema]]
**Focal neurologic deficits
**Altered level of consciousness (GCS <10-12)
*CSF findings:


==Diagnosis==
{| class="wikitable"
{| class="wikitable"
|+Clinical Tests for Meningitis
| align="center" style="background:#f0f0f0;"|'''Finding'''
| align="center" style="background:#f0f0f0;"|'''Description'''
| align="center" style="background:#f0f0f0;"|'''Sensitivity'''
| align="center" style="background:#f0f0f0;"|'''Specificity'''
|-
|-
| Nuchal rigidity||
! Parameter !! '''Bacterial''' !! '''Viral''' !! '''TB/Fungal'''
*Rigidity of neck muscles with flexion
|-
||13%<ref name="Nakao">Nakao JH, et al. Jolt accentuation of headache and other clinical signs: poor predictors of meningitis in adults. Am J Emerg Med. 2014;32(1):24-28.</ref>||80% <ref name="Nakao" />
| Opening pressure || '''Elevated (>20 cm H2O)''' || Normal/mild ↑ || Elevated
|-
| WBC || '''1000-5000+ (PMN predominant)''' || 10-500 (lymphocytes) || 50-500 (lymphocytes)
|-
|-
| Kernig's sign||
| Glucose || '''<40 mg/dL (or CSF:serum <0.4)''' || Normal || Low
*With flexed hip at 90°, extension of knee produces pain
||2%<ref name="Nakao" />||97%<ref name="Nakao" />
|-
|-
| Brudzinski's sign||
| Protein || '''Elevated (>250 mg/dL)''' || Mild elevation || Elevated
*Involuntary lifting of legs with passive flexion of the neck
||2%<ref name="Nakao" />||98%<ref name="Nakao" />
|-
|-
| [[EBQ:Jolt Test|Jolt Test]]||
| Gram stain || Positive in 60-90% || Negative || Negative (AFB rarely +)
*Horizontal rotation of the head at frequency of 2 rotations/second
*Exacerbation of pre-existing headache is positive test.
||100%?^||
|}
|}
^Although a 1991 study<ref>Jolt accentuation of headache: the most sensitive sign of CSF pleocytosis. Headache. 1991 Mar;31(3):167-71.</ref> showed high sensitivity with this test, multiple newer studies have cast doubt on its sensitivity.<ref>Absence of jolt accentuation of headache cannot accurately rule out meningitis in adults. Am J Emerg Med. 2013 Nov;31(11):1601-4</ref><ref>Jolt accentuation of headache and other clinical signs: poor predictors of meningitis in adults. Am J Emerg Med. 2014 Jan;32(1):24-8</ref> Although it may be clinically useful in the right subset of patients, it should not be considered to be 100% sensitive.
=== Work-Up  ===
#CBC
#Chem
#Blood cx
#?CT head: See [[CT Before Lumbar Puncture]]
#CXR (50% of pts w/ pneumoccocal meningitis have e/o pna on CXR)
#[[Lumbar Puncture]]


===[[Lumbar Puncture]] Diagnosis===
===Labs===
{{Lumbar Puncture Diagnosis}}
*Blood cultures (before antibiotics if possible)
*CBC, BMP, lactate, coagulation studies
*Procalcitonin (may help distinguish bacterial from viral; level >0.5 ng/mL supports bacterial)
*CSF studies: cell count with differential, protein, glucose, Gram stain, culture
*Consider: CSF lactate, HSV PCR, cryptococcal antigen, meningitis/encephalitis PCR panel


==Management==
==Management==
===[[Antibiotics]]===
===Empiric Antibiotics (Give IMMEDIATELY if Suspected)===
*''Give as soon as possible (if [[LP]] performed w/in 2hr of antibiotics, [[CSF]] culture will not be affected)''
*Adults <50 years:
{{Meningitis Antibiotics}}
**Ceftriaxone 2g IV q12h + vancomycin 15-20 mg/kg IV q8-12h
 
*Adults >50 years, immunocompromised, or alcoholics:
===[[EBQ:De_Gans_-_Steroids_for_Bacterial_Meningitis|Steroids]]===
**Ceftriaxone 2g IV q12h + vancomycin 15-20 mg/kg IV q8-12h + ampicillin 2g IV q4h (Listeria coverage)
*[[Dexamethasone]]
*Neonates:
**Only give prior to or with first dose of [[antibiotics]]
**Ampicillin + gentamicin (or ampicillin + cefotaxime)
**10mg IV q6hr x4d
*Post-neurosurgical/VP shunt:
 
**Vancomycin + cefepime (or meropenem)
''The only benefit is shown in patients with meningitis from [[Streptococcus pneumoniae]] with a possible mortality benefit and a decrease in hearing loss''<ref>Brouwer MC, McIntyre P, de Gans J, Prasad K, van de Beek D. Corticosteroids for Acute Bacterial Meningitis. Cochrane Database of Systematic Reviews 2010, Issue 9.</ref>


===AntiVirals===
===Dexamethasone===
*[[Acyclovir]]
*Dexamethasone 0.15 mg/kg IV q6h x 4 days
**Consider for pts w/ suspected viral meningitis who present w/ neurologic deficits
*Give with or just before FIRST dose of antibiotics<ref>de Gans J, van de Beek D. Dexamethasone in adults with bacterial meningitis. ''N Engl J Med''. 2002;347(20):1549-1556. PMID 12432041</ref>
**10mg/kg IV q8hr (Obese patients should be dosed using ideal body weight)
*Greatest benefit in pneumococcal meningitis (reduced mortality and hearing loss)
*If given >1 hour after antibiotics, benefit is reduced — '''do not withhold antibiotics for dexamethasone'''


===Osmotics===
===Viral Meningitis===
*[[Mannitol]]
*Supportive care (analgesia, antiemetics, IV fluids)
**Rarely used
*If '''HSV encephalitis''' suspected: '''acyclovir 10 mg/kg IV q8h''' (do NOT wait for confirmation)
**Only for marked cerebral edema


===Prophylaxis===
===Meningococcal Prophylaxis===
*For [[meningococcus]] exposure
*Close contacts of confirmed N. meningitidis require prophylaxis:
**Indications:
**Rifampin 600 mg PO q12h x 2 days OR
***Household contacts
**Ciprofloxacin 500 mg PO x 1 dose (preferred for adults) OR
***School or day care contacts in previous 7d
**Ceftriaxone 250 mg IM x 1 dose (preferred for pregnant women)
***Direct exposure to pt's secretions (kissing, shared utensils or toothbrush)
*Notify public health
***Intubation without facemask
**Meds
***[[Rifampin]] 600mg PO BID x2d OR [[ceftriaxone]] 250mg IM x1 OR [[ciprofloxacin]] 500mg PO x1


==Disposition==
==Disposition==
===Bacterial meningitis===
*Admit all patients with suspected bacterial meningitis to ICU or monitored bed
*Admit with [[droplet precautions]]
*Viral meningitis: may discharge if well-appearing, tolerating PO, reliable follow-up
 
*Repeat LP not routinely needed if clinically improving
===Viral meningitis===
*Admit for empiric [[antibiotics]] until culture results return OR
*Discharge w/ 24hr f/u


==See Also==
==See Also==
*[[Meningitis (Peds)]]
*[[Encephalitis]]
*[[Subarachnoid hemorrhage]]
*[[Lumbar puncture]]
*[[Meningitis (peds)]]
*[[Brain abscess]]
*[[Sepsis]]


== References==
==References==
<references/>
<references/>
*Tunkel AR, et al. Practice guidelines for the management of bacterial meningitis. ''Clin Infect Dis''. 2004;39(9):1267-1284. PMID 15494903
*Brouwer MC, et al. Epidemiology, diagnosis, and antimicrobial treatment of acute bacterial meningitis. ''Clin Microbiol Rev''. 2010;23(3):467-492. PMID 20610819
*McGill F, et al. Acute bacterial meningitis in adults. ''Lancet''. 2016;388(10063):3036-3047. PMID 27265346


[[Category:ID]]
[[Category:Infectious Disease]]
[[Category:Neuro]]
[[Category:Neurology]]
[[Category:Critical Care]]

Latest revision as of 09:26, 22 March 2026

Background

  • Inflammation of the meninges (membranes surrounding the brain and spinal cord)
  • Bacterial meningitis is a medical emergency — mortality 15-25% even with treatment; up to 50% untreated[1]
  • Time to antibiotics is the most critical intervention — every hour of delay increases mortality

Common Organisms by Age

  • Neonates (<1 month): Group B Streptococcus (GBS), E. coli, Listeria monocytogenes
  • Infants/Children (1 month - 18 years): Neisseria meningitidis, Streptococcus pneumoniae, Haemophilus influenzae type b (less common post-vaccination)
  • Adults (18-50): S. pneumoniae (most common), N. meningitidis
  • Adults >50, immunocompromised, alcoholics: S. pneumoniae, Listeria, gram-negative bacilli
  • Post-neurosurgical/VP shunt: Staphylococcus species, gram-negative bacilli

Viral Meningitis

  • Most common cause overall; enterovirus in majority
  • Generally self-limited; much better prognosis than bacterial

Clinical Features

  • Classic triad (headache, fever, neck stiffness): present in only ~44% of bacterial meningitis
  • At least 2 of 4 (headache, fever, neck stiffness, AMS) present in 95%[2]
  • Headache (87%), fever (77%), neck stiffness (83%)
  • Altered mental status (ranging from confusion to coma)
  • Photophobia
  • Kernig sign: pain with knee extension when hip is flexed (sensitivity ~5%)
  • Brudzinski sign: involuntary hip flexion with passive neck flexion (sensitivity ~5%)
  • Jolt accentuation: worsening headache with horizontal head rotation (better sensitivity than Kernig/Brudzinski)
  • Petechial/purpuric rash: highly suggestive of N. meningitidis (meningococcemia)
  • Neonates: irritability, poor feeding, bulging fontanelle, hypothermia or fever
  • Elderly: may present with only confusion without classic features

Differential Diagnosis

Template:Altered mental status and fever DDX

Evaluation

DO NOT DELAY ANTIBIOTICS FOR LP

  • If LP will be delayed (CT needed, patient unstable): give antibiotics FIRST, then CT, then LP
  • Blood cultures should be drawn before antibiotics when possible (do not delay abx for cultures)

Lumbar Puncture

  • CT BEFORE LP only if:
    • Immunocompromised, history of CNS disease
    • New-onset seizures
    • Papilledema
    • Focal neurologic deficits
    • Altered level of consciousness (GCS <10-12)
  • CSF findings:
Parameter Bacterial Viral TB/Fungal
Opening pressure Elevated (>20 cm H2O) Normal/mild ↑ Elevated
WBC 1000-5000+ (PMN predominant) 10-500 (lymphocytes) 50-500 (lymphocytes)
Glucose <40 mg/dL (or CSF:serum <0.4) Normal Low
Protein Elevated (>250 mg/dL) Mild elevation Elevated
Gram stain Positive in 60-90% Negative Negative (AFB rarely +)

Labs

  • Blood cultures (before antibiotics if possible)
  • CBC, BMP, lactate, coagulation studies
  • Procalcitonin (may help distinguish bacterial from viral; level >0.5 ng/mL supports bacterial)
  • CSF studies: cell count with differential, protein, glucose, Gram stain, culture
  • Consider: CSF lactate, HSV PCR, cryptococcal antigen, meningitis/encephalitis PCR panel

Management

Empiric Antibiotics (Give IMMEDIATELY if Suspected)

  • Adults <50 years:
    • Ceftriaxone 2g IV q12h + vancomycin 15-20 mg/kg IV q8-12h
  • Adults >50 years, immunocompromised, or alcoholics:
    • Ceftriaxone 2g IV q12h + vancomycin 15-20 mg/kg IV q8-12h + ampicillin 2g IV q4h (Listeria coverage)
  • Neonates:
    • Ampicillin + gentamicin (or ampicillin + cefotaxime)
  • Post-neurosurgical/VP shunt:
    • Vancomycin + cefepime (or meropenem)

Dexamethasone

  • Dexamethasone 0.15 mg/kg IV q6h x 4 days
  • Give with or just before FIRST dose of antibiotics[3]
  • Greatest benefit in pneumococcal meningitis (reduced mortality and hearing loss)
  • If given >1 hour after antibiotics, benefit is reduced — do not withhold antibiotics for dexamethasone

Viral Meningitis

  • Supportive care (analgesia, antiemetics, IV fluids)
  • If HSV encephalitis suspected: acyclovir 10 mg/kg IV q8h (do NOT wait for confirmation)

Meningococcal Prophylaxis

  • Close contacts of confirmed N. meningitidis require prophylaxis:
    • Rifampin 600 mg PO q12h x 2 days OR
    • Ciprofloxacin 500 mg PO x 1 dose (preferred for adults) OR
    • Ceftriaxone 250 mg IM x 1 dose (preferred for pregnant women)
  • Notify public health

Disposition

  • Admit all patients with suspected bacterial meningitis to ICU or monitored bed
  • Viral meningitis: may discharge if well-appearing, tolerating PO, reliable follow-up
  • Repeat LP not routinely needed if clinically improving

See Also

References

  1. ↑ van de Beek D, et al. Community-acquired bacterial meningitis. Nat Rev Dis Primers. 2016;2:16074. PMID 27808261
  2. ↑ van de Beek D, et al. Clinical features and prognostic factors in adults with bacterial meningitis. N Engl J Med. 2004;351(18):1849-1859. PMID 15509818
  3. ↑ de Gans J, van de Beek D. Dexamethasone in adults with bacterial meningitis. N Engl J Med. 2002;347(20):1549-1556. PMID 12432041
  • Tunkel AR, et al. Practice guidelines for the management of bacterial meningitis. Clin Infect Dis. 2004;39(9):1267-1284. PMID 15494903
  • Brouwer MC, et al. Epidemiology, diagnosis, and antimicrobial treatment of acute bacterial meningitis. Clin Microbiol Rev. 2010;23(3):467-492. PMID 20610819
  • McGill F, et al. Acute bacterial meningitis in adults. Lancet. 2016;388(10063):3036-3047. PMID 27265346
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