II. Epidemiology

  1. Annual Incidence: 1.5 per 100,000 persons (in 2003)

III. Pathophysiology

  1. Cerebrospinal Fluid deficient in immune factors
    1. Specific Antibody
    2. Functional complement
  2. Inefficient phagocytosis of pathogen

IV. Predisposing Factors: Adults

  1. Recent Otitis Media or Bacterial Sinusitis (25% of cases)
  2. Pneumonia (12% of cases)
  3. Immunocompromised state (16%)

VI. Symptoms

  1. General
    1. Fulminant onset <24 hours (25%)
    2. Respiratory illness precede onset by <7 days (50%)
  2. Presentation in Adults and Older Children
    1. Classic Triad (approaches 85% in some studies)
      1. Headache (87%)
      2. Stiff Neck (83%)
      3. Fever (77%)
    2. Classic triad symptoms and impaired consciousness
      1. Virtually all Bacterial Meningitis patients have one of these symptoms
      2. Two of four symptoms present in 95% of patients
    3. Other Presenting Symptoms
      1. Altered Level of Consciousness (69%)
      2. Vomiting (35%)
      3. Seizures (5%)
      4. Lethargy
      5. Irritability
      6. Confusion
  3. Newborns and Infants
    1. Presentation <1 month is subtle (e.g. Vomiting, lethargy, irritability)
    2. Temperature Instability (Hypothermia or Fever)
      1. Fever in only 60% of Meningitis cases <1 month old
    3. NO Nuchal Rigidity
    4. Listlessness
    5. Lethargy
    6. Irritability
    7. High pitched crying
    8. Refusal to eat
    9. Weak sucking response
    10. Vomiting
    11. Diarrhea
    12. Respiratory distress
    13. Bulging Fontanelle (late sign in 1/3 neonates)
    14. Seizures (40%)

VII. Signs

  1. Meningeal Irritation (50% of adult patients)
    1. Recent studies suggest low efficacy
      1. See Meningeal Irritation for specific studies
      2. Do not rely on these signs to diagnose Meningitis
    2. Nuchal Rigidity
      1. Unreliable in under age 18 months due to neck musculature not fully developed
    3. Spinal Rigidity
    4. Tests with high Test Specificity (but poor Test Sensitivity)
      1. Kernig's Sign
      2. Brudzinski's Sign
  2. Skin Rash Causes
    1. Meningococcal Meningitis (present in 65% of Meningococcal Meningitis)
    2. HaemophilusInfluenzae
    3. Pneumococcal Meningitis
    4. Echovirus type 9
    5. Staphylococcus aureus
  3. Other Neurologic Signs (more common in Pneumococcal Meningitis)
    1. Cranial Nerve Palsies
    2. Altered Level of Consciousness
    3. Focal Neurologic Signs (10-20%)
    4. Seizures
    5. Papilledema (3%)
  4. Atypical presentations (classic signs often absent in these groups)
    1. Age over 65 may present with Seizures or Hemiparesis
    2. Young children may present with lethargy, irritability or Seizures

VIII. Differential Diagnosis

X. Diagnosis

  1. Lumbar Puncture (see evaluation for LP indications)
  2. Consider CT Head prior to Lumbar Puncture
    1. See Lumbar Puncture for CT Head indications (to rule out CNS mass)
    2. However, do not delay empiric antibiotics for CT Head
    3. Obtain Blood Cultures immediately and then administer empiric antibiotics even before Head CT and Lumbar Puncture completed

XI. Labs

  1. CSF Exam consistent with Bacterial Meningitis
    1. See Nigrovic Clinical Decision Rule
    2. CSF Leukocytes
      1. Over 500 (mean 5k-20k) with >80% Neutrophils
      2. Over 50k suggests Brain Abscess
      3. May be 100 (with only 50% Neutrophils) in Listeria infection
    3. CSF Opening Pressure
      1. Exceeds 180 mm H2O
    4. CSF Protein
      1. CSF Protein >100 mg/dl (may be normal with listeria)
      2. Range: 100-500 mg/dl (typically >250 mg/dl in Bacterial Meningitis)
    5. CSF Glucose
      1. Less than 40% of Blood Glucose (or less than 40 mg/dl)
    6. CSF Gram Stain Positive
      1. Test Sensitivity 75% (untreated)
    7. CSF Culture Positive
      1. Test Sensitivity 70-80%
  2. Blood Culture (40-60% sensitivity)
    1. HaemophilusInfluenzae (uncommon now due to Vaccine)
    2. Streptococcus Pneumoniae
    3. Neisseria Meningitidis
  3. Complete Blood Count
    1. Peripheral White Blood Cell Count does not distinguish Bacterial Meningitis from Aseptic Meningitis
    2. A normal White Blood Cell Count does not rule-out Bacterial Meningitis (esp. in young children)
  4. Urine Culture
    1. Indicated in infants

XII. Imaging

  1. Consider head imaging

XIII. Management

XIV. Complications

  1. Increased Intracranial Pressure
    1. See Bacterial Meningitis Management
  2. Seizures (20-30% of children with Bacterial Meningitis)
    1. Evaluate for Hypoglycemia and Hyponatremia
    2. See Status Epilepticus
    3. Consider anticonvulsants for prolonged or recurrent Seizures
  3. Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH)
  4. Subdural Effusion (15-40% of children with Bacterial Meningitis)
    1. Risk factors include younger age, Leukopenia, higher CSF Protein
    2. Consider Subdural Empyema in clinical deterioration

XV. Prevention

  1. Meningococcal Vaccine
  2. Adult Pneumococcal Vaccine
    1. Decreases Bacterial Meningitis risk by 50%

XVI. Prognosis

  1. Overall mortality: 15.6%
  2. Meningococcal
    1. Meningococcemia: Prognosis poor (20-30% fatality)
    2. Meningitis alone: Better prognosis (4-5% case fatality)
  3. Pneumococcal
    1. Case fatality rate 10% in children (30% in adults)
    2. Morbidity >30% (Hearing Loss common in children)

XVII. Reference

  1. Fuchs and Yamamoto (2012) APLS, Jones and Bartlett, Burlington, p. 175-80
  2. Gilbert (1998) Sanford Guide to Antimicrobial Therapy
  3. Wilson (1991) Harrison's Internal Medicine, p. 651-2
  4. Choi (2001) Clin Infect Dis 33:1380-5 [PubMed]
  5. Tunkel (1997) Am Fam Physician 56(5):1355-62 [PubMed]

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Ontology: Meningitis (C0025289)

Definition (MSH) Inflammation of the coverings of the brain and/or spinal cord, which consist of the PIA MATER; ARACHNOID; and DURA MATER. Infections (viral, bacterial, and fungal) are the most common causes of this condition, but subarachnoid hemorrhage (HEMORRHAGES, SUBARACHNOID), chemical irritation (chemical MENINGITIS), granulomatous conditions, neoplastic conditions (CARCINOMATOUS MENINGITIS), and other inflammatory conditions may produce this syndrome. (From Joynt, Clinical Neurology, 1994, Ch24, p6)
Definition (CHV) brain infection
Definition (CHV) brain infection
Definition (MEDLINEPLUS)

Meningitis is inflammation of the thin tissue that surrounds the brain and spinal cord, called the meninges. There are several types of meningitis. The most common is viral meningitis, which you get when a virus enters the body through the nose or mouth and travels to the brain. Bacterial meningitis is rare, but can be deadly. It usually starts with bacteria that cause a cold-like infection. It can block blood vessels in the brain and lead to stroke and brain damage. It can also harm other organs. Pneumococcal infections and meningococcal infections can cause bacterial meningitis.

Anyone can get meningitis, but it is more common in people whose bodies have trouble fighting infections. Meningitis can progress rapidly. You should seek medical care quickly if you have

  • A sudden fever
  • A severe headache
  • A stiff neck

Early treatment can help prevent serious problems, including death. Vaccines can prevent some of the bacterial infections that cause meningitis. Parents of adolescents and students living in college dorms should talk to a doctor about the vaccination.

NIH: National Institute of Neurological Disorders and Stroke

Definition (NCI_NCI-GLOSS) Inflammation of the meninges (three thin layers of tissue that cover and protect the brain and spinal cord). Meningitis is usually caused by a bacterial or viral infection, but sometimes is caused by cancer, drug allergies, or inflammatory diseases.
Definition (NCI_CTCAE) A disorder characterized by acute inflammation of the meninges of the brain and/or spinal cord.
Definition (NCI) A disorder characterized by acute inflammation of the meninges of the brain and/or spinal cord.
Definition (CSP) inflammation of the meninges.
Concepts Disease or Syndrome (T047)
MSH D008581
ICD9 322.9, 322
ICD10 G03.9 , G03
SnomedCT 192681009, 154983000, 192678004, 7180009
LNC LP20756-0, LA7454-7
English Meningitides, Meningitis, Meningitis of unspecified cause, Meningitis - unspecified cause, Meningitis, unspecified, Unspecified meningitis, meningitis, meningitis (diagnosis), Meningitis NOS, meningitis NOS, Meningitis [Disease/Finding], meningitides, Unspecified meningitis (disorder), Meningitis of unspecified cause (disorder), Inflammation of meninges, MENINGITIS, Meningitis (disorder), infection; brain, membranes, Meningitis, NOS
French MENINGITE, Méningite, non précisée, Méningite de cause non précisée, Méningite SAI, Méningite
Portuguese MENINGITE, Meningite NE, Meningite de causa NE, Meningite
Spanish MENINGITIS, Meningitis de causa no especificada, Meningitis no especificada, Meningitis NEOM, meningitis de causa no especificada (trastorno), meningitis no especificada, meningitis de causa no especificada, meningitis no especificada (trastorno), meningitis (trastorno), meningitis, Meningitis
Dutch meningitis door niet-gespecificeerde oorzaak, meningitis, niet-gespecificeerd, meningitis NAO, infectie; hersenen, vliezen, Meningitis, niet gespecificeerd, meningitis, Meningitis
German Meningitis NNB, Meningitis, unspezifisch, Meningitis unspezifischer Ursache, HIRNHAUTENTZUENDUNG, Meningitis, nicht naeher bezeichnet, Meningitis, Hirnhautentzündung
Italian Meningite NAS, Meningite da causa non specificata, Meningite, non specificata, Meningite
Japanese 髄膜炎NOS, 髄膜炎、詳細不明, 原因不明の髄膜炎, 髄膜炎, ズイマクエンNOS, ズイマクエンショウサイフメイ, ズイマクエン, ゲンインフメイノズイマクエン
Swedish Hjärnhinneinflammation
Czech meningitida, zánět mozkových blan, Meningitida, Meningitida, blíže neurčená, Meningitida NOS, Meningitida blíže neurčeného původu
Finnish Aivokalvotulehdus
Korean 상세불명의 수막염
Polish Zapalenie opon
Hungarian meningitis k.m.n., Meningitis, nem meghatározott, Nem meghatározott etiológiájú meningitis, meningitis
Norwegian Hjernehinnebetennelse, Meningitt

Ontology: Meningitis, Bacterial (C0085437)

Definition (MSH) Bacterial infections of the leptomeninges and subarachnoid space, frequently involving the cerebral cortex, cranial nerves, cerebral blood vessels, spinal cord, and nerve roots.
Definition (CSP) bacterial infections of the leptomeninges and subarachnoid space, frequently involving the cerebral cortex, cranial nerves, cerebral blood vessels, spinal cord and nerve roots; causative organism varies with age and clinical status (eg, postoperative, immunodeficient, posttraumatic states); clinical manifestations include the acute onset of fever, stiff neck, altered mentation, seizures, and focal neurologic deficits; death may occur within 24 hours of disease onset; pathologic features include a purulent exudate in the subarachnoid space, and diffuse inflammation of neural and vascular structures.
Concepts Disease or Syndrome (T047)
MSH D016920
ICD9 320.9, 320
ICD10 G00.9 , G00
SnomedCT 192662001, 267680008, 154984006, 95883001
English Bacterial Meningitides, Bacterial Meningitis, Meningitides, Bacterial, Meningitis, Bacterial, Meningitis due to unspecified bacterium, Bacterial meningitis, unspecified, MENINGITIS BACTERIAL, MENINGITIS BACT, BACT MENINGITIDES, BACT MENINGITIS, MENINGITIDES BACT, bacterial meningitis, bacterial meningitis (diagnosis), Meningitis bacterial NOS, Bacterial meningitis NOS, Meningitis, Bacterial [Disease/Finding], Meningitis;bacterial, bacterial meningitides, Bacterial meningitis NOS (disorder), Meningitis bacterial, Bacterial meningitis, BM - Bacterial meningitis, Bacterial meningitis (disorder), bacterial; meningitis, meningitis; bacterial, Bacterial meningitis, NOS, Meningitis, bacterial NOS
Portuguese MENINGITE BACTERIANA, Meningite bacteriana NE, Meningite por bactéria NE, Meningites Bacterianas, Meningite Bacteriana, Meningite por Bactéria, Meningites por Bactérias, Meningite por Bactérias, Meningite bacteriana
Dutch meningitis bacterieel NAO, meningitis door niet-gespecificeerde bacterie, bacteriële meningitis, bacterieel; meningitis, meningitis; bacterieel, Bacteriële meningitis, niet gespecificeerd, hersenvliesontsteking bacterieel, Bacteriële meningitis, Meningitis, bacteriële
French Méningite bactérienne SAI, Méningite due à une bactérie non précisée, MENINGITE BACTERIENNE, Méningite bactérienne
German Meningitis bakteriell NNB, Meningitis infolge einer unspezifischen Bakterie, Bakterielle Meningitis, nicht naeher bezeichnet, MENINGITIS BAKTERIELL, bakterielle Meningitis, Meningitis, bakterielle, Bakterielle Meningitis
Italian Meningite batterica NAS, Meningite da batteri non specificati, Meningite batterica
Spanish Meningitis por bacterias, Meningitis bacteriana NEOM, Meningitis por bacterias no especificadas, Meningitis Bacterianas, Meningitis Bacteriana, meningitis bacteriana, SAI, meningitis bacteriana, SAI (trastorno), Meningitis por Bacterias, meningitis bacteriana (trastorno), meningitis bacteriana, Meningitis bacteriana
Japanese 詳細不明の細菌による髄膜炎, 細菌性髄膜炎NOS, ショウサイフメイノサイキンニヨルズイマクエン, サイキンセイズイマクエン, サイキンセイズイマクエンNOS, 細菌性髄膜炎, 髄膜炎-細菌性
Swedish Hjärnhinneinflammation, bakteriell
Czech meningitida bakteriální, Bakteriální meningitida, Bakteriální meningitida NOS, Meningitida způsobená blíže určenými bakteriemi
Finnish Bakteerimeningiitti
Korean 상세불명의 세균성 수막염
Polish Zapalenie opon bakteryjne, Zapalenie opon mózgowych bakteryjne
Hungarian Nem meghatározott bacterium okozta meningitis, Bacterialis meningitis, bacterialis meningitis k.m.n., bacterialis meningitis
Norwegian Bakteriell meningitt, Meningitt, bakteriell