Meningitis: Difference between revisions

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==Adult==
==Background==
=== Background ===
*Inflammation of the meninges (membranes surrounding the brain and spinal cord)
*Microbiology
*'''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>
**Bacterial meningitis:
*Time to antibiotics is the most critical intervention — every hour of delay increases mortality
***Pneumococcus (60%), meningococcus (15%), GBS (15%), H flu (7%), listeria (2%)
**Viral meningitis
***Echo, coxsackie, entero (85%)
***HSV, CMV
*Pathophysiology
**Hematogenous spread via respiratory tract
**Contiguous spread (otitis media, sinusitis, brain abscess)


=== Risk Factors ===
===Common Organisms by Age===
#Otitis media
*Neonates (<1 month): Group B Streptococcus (GBS), ''E. coli'', ''Listeria monocytogenes''
#Sinusitis
*Infants/Children (1 month - 18 years): ''Neisseria meningitidis'', ''Streptococcus pneumoniae'', ''Haemophilus influenzae'' type b (less common post-vaccination)
#Immunosuppression/splenectomy
*Adults (18-50): S. pneumoniae (most common), N. meningitidis
#Alcoholism
*Adults >50, immunocompromised, alcoholics: S. pneumoniae, Listeria, gram-negative bacilli
#Pneumonia
*Post-neurosurgical/VP shunt: ''Staphylococcus'' species, gram-negative bacilli
#DM
#CSF leak
#Endocarditis
#Neurosurgical procedure / head injury
#Indwelling neurosurgical device / cochlear implant
#Malignancy


=== Clinical Features ===
===Viral Meningitis===
*Almost all patients present w/ at least 2 of the following:
*Most common cause overall; enterovirus in majority
**Headache
*Generally self-limited; much better prognosis than bacterial
**Fever
**Neck stiffness
**Altered mental status
*Also may have:
**Photophobia
**Vomiting
**Prodromal URI
**Focal neuro sx (e.g. CN deficit)
**Seizure (25%)
*Jolt Test (~100% Sn)
**Have pt rapidly shake head L and R; if does not bother pt unlikely to have meningitis


=== 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


===Diagnosis===
==Differential Diagnosis==
{| style="width: 500px" border="1" cellpadding="1" cellspacing="1"
*[[Subarachnoid hemorrhage]]
*[[Encephalitis]]
*Brain abscess
*[[Subdural hemorrhage]] / epidural abscess
*[[Stroke]]
*Viral meningitis
*Carcinomatous meningitis
*Drug-induced meningitis (NSAIDs, IVIG, TMP-SMX)
 
{{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:
 
{| class="wikitable"
|-
|-
| '''Measure'''<br>
! Parameter !! '''Bacterial''' !! '''Viral''' !! '''TB/Fungal'''
| '''Bacterial'''<br>
| '''Viral'''<br>
| '''Fungal'''<br>
| '''Neoplastic'''<br>
|-
|-
| Opening Pressure<br>  
| Opening pressure || '''Elevated (>20 cm H2O)''' || Normal/mild ↑ || Elevated
| &gt;30
| &lt;30
| ~30
| ~20
|-
|-
| WBC Count<br>
| WBC || '''1000-5000+ (PMN predominant)''' || 10-500 (lymphocytes) || 50-500 (lymphocytes)
| &gt;1000<br>
| &lt;1000<br>
| &lt;500<br>
| &lt;500<br>
|-
|-
| &nbsp;% PMNs<br>
| Glucose || '''<40 mg/dL (or CSF:serum <0.4)''' || Normal || Low
| &gt;80%<br>
| 1-50%<br>
| 1-50%<br>
| 1-50%<br>
|-
|-
| Glucose<br>  
| Protein || '''Elevated (>250 mg/dL)''' || Mild elevation || Elevated
| &lt;40<br>
| &gt;40<br>
| &lt;40<br>
| &lt;40<br>
|-
|-
| Protein<br>
| Gram stain || Positive in 60-90% || Negative || Negative (AFB rarely +)
| &gt;200<br>
| &lt;200<br>
| &gt;200<br>
| &gt;200<br>
|-
| Gram Stain<br>
| Pos
| neg<br>
| India ink<br>
| <br>
|}
|}


^For bloody tap, subtract 1 WBC for every 250 RBC
===Labs===
 
*Blood cultures (before antibiotics if possible)
=== DDX  ===
*CBC, BMP, lactate, coagulation studies
#Encephalitis
*Procalcitonin (may help distinguish bacterial from viral; level >0.5 ng/mL supports bacterial)
#Brain mass
*CSF studies: cell count with differential, protein, glucose, Gram stain, culture
#Brain abscess
*Consider: CSF lactate, HSV PCR, cryptococcal antigen, meningitis/encephalitis PCR panel
#SAH
#Migraine
 
=== 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)
#CSF studies
##Glucose and protein (Tube 1)
##Gram stain and culture (Tube 2)
##Cell count and differential (Tube 3)
##Special studies if indicated (HSV PCR, india ink) - Tube 2
##Hold (Tube 4)
 
=== Treatment  ===
#Abx
##Give as soon as possible (if LP performed w/in 2hr of abx CSF culture will not be affected)  
##Guidelines
###Age 18-50y
####Ceftriaxone 2gm IV q12hr + vancomycin 15mg/kg q8-12hr
#####(vancomycin is for resistant pneumococcus)
###Age >50y
####Ceftriaxone 2gm IV q12hr + vancomycin 15mg/kg q8-12hr + ampicillin 2gm IV q4h
#####Ampicillin is for listeria)
###CSF leak w/ history of closed head trauma
####Ceftriaxone 2gm IV q12hr + vancomycin 15mg/kg q8-12hr
###History of recent penetrating head injury, neurosurgery, CSF shunt
####(Ceftazidime 2gm IV q8hr or cefepime or meropenem) + vanco 25 milligrams/kg load
###Meningitis due to sinusitis
####Ceftriaxone + metronidazole
#Dexamethasone
##Only give prior to or w/ first dose of abx
##10mg IV q6hr x4d
#Mannitol
##For marked cerebral edema
#Acyclovir
##Consider for pts w/ suspected viral menengitis who present w/ neuro deficits
##10mg/kg IV q8hr
 
=== Prophylaxis  ===
*For meningococcus exposure
**Indications:
***Household contacts
***School or day care contacts in previous 7d
***Direct exposure to pt's secretions (kissing, shared utensils or toothbrush)
***Intubation without facemask
**Meds
***Rifampin 600mg PO BID x2d OR CTX 250mg IM x1 OR ciprofloxacin 500mg PO x1
 
===Disposition===
#Bacterial meningitis
##Admit w/ droplet precautions
#Viral meningitis
##Admit for empiric abx until culture results return OR
##Discharge w/ 24hr f/u
 
==Pediatric==
===Background===
*Meningismus is difficult to discern if <6mo, (esp if <2mo)
*<3months old
**1% incidence of bacterial meningitis
**E. coli, Group B strep, listeria
*>3months old
**S. pneumo, meningococcus, staph
 
===Diagnosis===
Bacterial Meningitis Score for >2mo and well-appearing
*Risk Factor
**Peripheral blood ANC >10K
**Seizure
**CSF
***CSF ANC >1000
***CSF protein >80
***CSF Gram stain (if + 61% Sn, 99% Sp)


*Any risk factor = high risk for bacterial meningitis
==Management==
*Very low risk if infant lacks all risk factors
===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)


===Work-Up===
===Dexamethasone===
#CBC
*Dexamethasone 0.15 mg/kg IV q6h x 4 days
#CSF
*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>
*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'''


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


===Treatment===
===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===
==Disposition==
*Admit despite negative meningitis score if:
*Admit all patients with suspected bacterial meningitis to ICU or monitored bed
**Age <2mo w/ any degree of pleocytosis
*Viral meningitis: may discharge if well-appearing, tolerating PO, reliable follow-up
**Appear ill
*Repeat LP not routinely needed if clinically improving
**Infants w/ aseptic meningitis
*If likely viral meningitis still give CTX x 1, f/u in 24hr


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


== Source ==
==References==
Tintinalli
<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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