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MeningitisAka: Bacterial Meningitis, Acute Bacterial Meningitis

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  1. Pathophysiology
    1. Cerebrospinal Fluid deficient in immune factors
      1. Specific Antibody
      2. Functional complement
    2. Inefficient phagocytosis of pathogen
  2. Causes
    1. Elderly adults
      1. Streptococcus Pneumoniae
      2. Escherichia coli
      3. Klebsiella Pneumoniae
      4. Streptococcus agalactiae (Group B Streptococcus)
      5. Listeria monocytogenes
    2. Adults
      1. Streptococcus Pneumoniae (30-50%)
      2. Neisseria Meningitidis (10-35%)
      3. Staphylococci (5-15%)
      4. Haemophilus Influenzae (1-3%)
      5. Gram Negative Bacilli (1-10%)
      6. Streptococcus species
      7. Listeria monocytogenes
    3. Children or Infants
      1. Streptococcus Pneumoniae (10-20%)
      2. Neisseria Meningitidis (25-40%)
      3. Haemophilus Influenzae (40-60%)
        1. Markedly reduced with Immunizations
    4. Neonates
      1. Group B Streptococcus (49%)
      2. Escherichia coli (18%)
      3. Listeria monocytogenes (7%)
      4. Non-Group B Streptococcus
  3. Symptoms
    1. General
      1. Fulminant onset <24 hours (25%)
      2. Respiratory illness precede onset by <7 days (50%)
    2. Adults and Children
      1. Classic Triad (85% with bacterial meningitis)
        1. Fever
        2. Headache
        3. Stiff Neck
      2. Other Presenting Symptoms
        1. Vomiting (35%)
        2. Seizures (30%)
        3. Impaired consciousness
    3. Newborns and Infants
      1. Temperature Instability (Hypothermia or Fever)
      2. Listlessness
      3. Lethargy
      4. Irritability
      5. High pitched crying
      6. Refusal to eat
      7. Weak sucking response
      8. Vomiting
      9. Diarrhea
      10. Respiratory distress
      11. Bulging Fontanelle (late sign in 1/3 neonates)
      12. Seizures (40%)
  4. 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
      3. Spinal Rigidity
      4. Kernig's Sign
      5. Brudzinski's Sign
    2. Skin Rash Causes
      1. Meningococcal Meningitis (50%)
      2. Haemophilus Influenzae
      3. Pneumococcal Meningitis
      4. Echovirus type 9
      5. Staphylococcus aureus
    3. Other Neurologic Signs
      1. Cranial Nerve Palsies
      2. Focal Cerebral Signs (10-20%)
      3. Papilledema (<1%)
  5. Evaluation
    1. See Oostenbrink Clinical Decision Rule for Meningitis
  6. Diagnosis
    1. Lumbar Puncture (see evaluation for LP indications)
  7. Labs
    1. CSF Exam consistent with Bacterial Meningitis
      1. See Nigrovic Clinical Decision Rule
      2. CSF Leukocytes
        1. Over 1k (mean 5k-20k) with >80% Neutrophils
        2. Over 50k suggests brain abscess
      3. CSF Opening Pressure
        1. Exceeds 180 mm H2O
      4. CSF Protein
        1. Range: 1.5-5.0 g/L (100-500 mg/dl)
      5. CSF Glucose
        1. Less than 40% of Blood Glucose
      6. CSF Gram Stain Positive
        1. Sensitivity 75% (untreated)
      7. CSF Culture Positive
        1. Sensitivity 70-80%
    2. Blood Culture (40-60% sensitivity)
      1. Haemophilus Influenzae (uncommon now due to vaccine)
      2. Streptococcus Pneumoniae
      3. Neisseria Meningitidis
  8. Management
    1. See Bacterial Meningitis Management
  9. Prevention
    1. Meningococcal Vaccine
    2. Adult Pneumococcal Vaccine
      1. Decreases bacterial meningitis risk by 50%
  10. Prognosis
    1. Meningococcal
      1. Meningococcemia: Prognosis poor (20-30% fatality)
      2. Meningitis: better prognosis (4-5% case fatality)
    2. Pneumococcal
      1. Case fatality rate 10% in children (30% in adults)
      2. Morbidity >30% (Hearing Loss common in children)
  11. Reference
    1. Gilbert (1998) Sanford Guide to Antimicrobial Therapy
    2. Wilson (1991) Harrison's Internal Medicine, p. 651-2
    3. Choi (2001) Clin Infect Dis 33:1380
    4. Tunkel (1997) Am Fam Physician 56(5):1355

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 (e.g., carcinomatous meningitis), and other inflammatory conditions may produce this syndrome. (From Joynt, Clinical Neurology, 1994, Ch24, p6)
Definition (CSP)inflammation of the meninges.
ConceptsDisease or Syndrome (T047)
ICD9322, 322.9, V12.42
EnglishMeningitides, Meningitis, Meningitis of unspecified cause, Unspecified meningitis
Spanishmeningitis, meningitis de causa no especificada, meningitis no especificada
CreditsDerived from the NIH UMLS (Unified Medical Language System)


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. The type of causative organism varies with age and clinical status (e.g., post-operative, immunodeficient, or post-traumatic 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. (From Joynt, Clinical Neurology, 1994, Ch24, pp1-5)
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.
ConceptsDisease or Syndrome (T047)
ICD9320, 320.9
EnglishBACT MENINGITIDES, BACT MENINGITIS, Bacterial Meningitides, Bacterial meningitis, MENINGITIDES BACT, MENINGITIS BACT, Meningitis due to unspecified bacterium
Spanishmeningitis bacteriana
CreditsDerived from the NIH UMLS (Unified Medical Language System)



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