Meningitis: Difference between revisions

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Def: inflammation of the leptomeninges and underlying subarachnoid CSF
==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<ref>van de Beek D, et al. Community-acquired bacterial meningitis. ''Nat Rev Dis Primers''. 2016;2:16074. PMID 27808261</ref>
*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


3 types:
===Viral Meningitis===
*Most common cause overall; enterovirus in majority
*Generally self-limited; much better prognosis than bacterial


* acute (<24 hrs): usually bacterial in origin (25%)
==Clinical Features==
* subacute (1-7 days): viral or bacterial
*Classic triad (headache, fever, neck stiffness): present in only ~44% of bacterial meningitis
* chronic (>7 days): viral, TB, syphilis, fungi, carcinomatous
*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>
*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


Risk Factors:
==Differential Diagnosis==
*[[Subarachnoid hemorrhage]]
*[[Encephalitis]]
*Brain abscess
*[[Subdural hemorrhage]] / epidural abscess
*[[Stroke]]
*Viral meningitis
*Carcinomatous meningitis
*Drug-induced meningitis (NSAIDs, IVIG, TMP-SMX)


* Age >60 or <5
{{Altered mental status and fever DDX}}
* Immunosuppressed/Immunocompromised (DM, adrenal insufficiency, HIV, cystic fibrosis, pts on steroids, Sickle Cell, etc)
* Crowding (military, college dorm rooms)
* Alcoholism/cirrhosis
* Recent exposure to someone with meningitis
* Contiguous infection  Dural defect (traumatic, surgical (VP shunt))
* Thalassemia major  IVDA  Endocarditis  Malignancy


Signs/Symptoms:
==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)


* Headache
===Lumbar Puncture===
* Nuchal rigidity (may not be present in those with AMS)
*CT BEFORE LP only if:
* Fevers/chills
**Immunocompromised, history of CNS disease
* Photophobia
**New-onset [[seizures]]
* Vomiting
**[[Papilledema]]
* Prodromal URI
**Focal neurologic deficits
* Focal neuro sx (ie seizure)
**Altered level of consciousness (GCS <10-12)
* AMS (may be the only complaint esp in elderly)  
*CSF findings:


Physical Exam Findings
{| class="wikitable"
|-
! 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 +)
|}


* Signs of Meningeal Irritation:
===Labs===
* Kernigs: passive knee extension while pt is supine causes neck pain and hamstring resistanc
*Blood cultures (before antibiotics if possible)
* Brudzinski: when you flex pts neck you see involuntary flexion of b/l lower ext
*CBC, BMP, lactate, coagulation studies
* Fever
*Procalcitonin (may help distinguish bacterial from viral; level >0.5 ng/mL supports bacterial)
* Rash
*CSF studies: cell count with differential, protein, glucose, Gram stain, culture
* Abnl Neuro exam (altered, focal cranial nerve defect)
*Consider: CSF lactate, HSV PCR, cryptococcal antigen, meningitis/encephalitis PCR panel
* papillaedema 


Differential Diagnosis:
==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)


* encephalitis
===Dexamethasone===
* brain mass
*Dexamethasone 0.15 mg/kg IV q6h x 4 days
* brain abscess
*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>
* subarachnoid hemorrhage
*Greatest benefit in pneumococcal meningitis (reduced mortality and hearing loss)
* migraine
*If given >1 hour after antibiotics, benefit is reduced — '''do not withhold antibiotics for dexamethasone'''


Orders/Workup
===Viral Meningitis===
*Supportive care (analgesia, antiemetics, IV fluids)
*If '''HSV encephalitis''' suspected: '''acyclovir 10 mg/kg IV q8h''' (do NOT wait for confirmation)


* isolation of patient (if suspect bacterial meningitis)
===Meningococcal Prophylaxis===
* cbc
*Close contacts of confirmed N. meningitidis require prophylaxis:
* blood cultures
**Rifampin 600 mg PO q12h x 2 days OR
* coags
**Ciprofloxacin 500 mg PO x 1 dose (preferred for adults) OR
* chem panel
**Ceftriaxone 250 mg IM x 1 dose (preferred for pregnant women)
* CT head
*Notify public health
* CXR (50% of pts w/pneumoccocal meningitis have e/o pna on CXR)  
* CSF studies
* cell count
* gram stain
* culture
* glucose
* protein
* special studies if indicated (i.e. HSV PCR or india ink in HIV pt)  
Interpreting CSF


==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


Bacterial Viral Fungal Neoplastic
==See Also==
Opening Pressure ↑↑ Normal, mild ↑ Normal, mild ↑ Normal, mild ↑
*[[Encephalitis]]
Cell Cnt >1000 <1000 <500 <500
*[[Subarachnoid hemorrhage]]
% PMNs >80% 1-50% 1-50% 1-50%
*[[Lumbar puncture]]
Glucose <40 >40 <40 <40
*[[Meningitis (peds)]]
Protein >200 <200 >200 >200
*[[Brain abscess]]
Gram stain + (80% effective) neg AFB, India ink
*[[Sepsis]]


==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


Treatment
[[Category:Infectious Disease]]
 
[[Category:Neurology]]
Goal is to initiate treatment within 30 minutes of presentation (if pt is acutely ill). Abx givein 2 hr prior to LP will NOT decrease the sensitivity of CSF culture
[[Category:Critical Care]]
 
Antibiotics
 
* Neonates: Ampicillin + cefotaxime or amp +gent
* Infants(3 mo): Ampicillin + Cefotax or Ceftriaxone
* Children: Cefotax or Ceftriaxone
* Adults: Cefotaxime or ceftriaxone + vanco; Add Ampicillin if Listeria suspected
 
Steroids*
 
(Dexamethasone 0.15mg/kg Q6hrsx4dys; 10mg max) --give 15-20 minutes before antibiotics
 
Neonates (<6wks) --> No
 
Infants/child --> Yes
 
Adults --> Yes
 
*prior to or with abx = only group w/ benifit
 
 
PROPHYLAXIS (N. meningit)
 
*Rx primary caregivers (those in close contact to  nasopharyngeal secretions or those who were with the patient at least 4 hours during week before onset of symptoms)
 
Cipro 500mg PO x 1 or rifampin x 4 doses or ceftriaxone x1
 
 
 
 
 
[[Category:ID]]

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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