Meningits Flashcards
(36 cards)
Meningitis is inflammation of the _______-meninges
Leptomeninges
What are the common sources for infection of the meninges?
- Hematogenous spread
- Contiguous spread from sinusitis, otitis, trauma, or surgery
- Retrograde from peripheral nerves
What two clinical signs are associated with meningitis?
- Kernig sign
- Brudzinski sign
Nuchal rigidity and a positive Brudzinski sign, in which passive neck flexion causes involuntary flexion of the knees and hips, are indicative of meningeal irritation.
What is the best initial step in diagnosing meningitis?
Lumbar puncture in MOST instances (key contraindications should be recognized).
When is a CT scan of the head indicated before lumbar puncture in suspected meningitis?
Patients with signs of increased intracranial pressure (papilledema, focal neurological deficits, altered mental status, seizures) to rule out brain mass.
What is the next step if bacterial meningitis is strongly suspected, but a CT scan is required before performing a lumbar puncture?
- Do NOT delay empiric antibiotics if imaging is warranted
- Patients otherwise get treatment with empiric abx following an LP
What are the distinctive signs between meningitis and encephalitis and meningitis?
- Meningitis tends to present with fever, nuchal rigidity, headaches, lethargy but and intact sensorium
- Encephalitis can have all of these, but tends to also include altered mental status (eg, confusion, behavioral changes), seizures, and diffuse or focal neurologic abnormalities (eg, hypertonicity, hyperreflexia, weakness).
- It is important to note that both can demonstrate seizure and focal deficits
What are the typical CSF findings in bacterial meningitis?
- Elevated WBC count (>1,000 cells/μL) with neutrophilic predominance (> 80% PMNs)
- Decreased glucose (<40 mg/dL)
- Elevated protein (>100 mg/dL)
- Gram stain (+)
- Increased opening pressure (> 250 mm H2O)
What are the typical CSF findings in viral (aseptic) meningitis?
- Moderate WBC count (5 - 1,000 cells/μL) with lymphocytic predominance (> 50% lymphocytes)
- Normal glucose (~ 60 mg/dL)
- Mild protein elevation (40 - 140 mg/dL)
What are the typical CSF findings in fungal meningitis?
- Moderate WBC count (20 - 2000 cells/μL) with lymphocytic predominance (> 50% lymphocytes)
- Markedly elevated protein (100 - 500 mg/dL)
- Normal to Low glucose
What are the typical CSF findings in fungal or tuberculosis (TB) meningitis?
- Moderate WBC count (20 - 2000 cells/μL) with lymphocytic predominance (> 80% lymphocytes)
- Markedly elevated protein (100 - 500 mg/dL)
- Low glucose
- Acid-fast bacilli in her cerebrospinal fluid (CSF)
- Basilar meningeal enhancement commonly seen in CT
Treatment:
Prolonged treatment is required with 2 months of 4-drug therapy (isoniazid, rifampin, pyrazinamide, and either a fluoroquinolone or injectable aminoglycoside), followed by 9-12 months of continuation therapy (isoniazid plus rifampin). As antitubercular treatment can result in a transient worsening of central nervous system inflammation, patients with tuberculous meningitis are typically given 6-8 weeks of adjuvant glucocorticoid therapy (dexamethasone or prednisone). This significantly reduces morbidity and mortality.
What are the causes of aseptic meningitis with an increased protein concentration?
- The most common is TB.
- Enteroviruses (coxsackie, echovirus)
- HIV
- HSV
- VZV
- Syphilis
- Lyme disease
What are the most common causes of bacterial meningitis in neonates (<1 month)?
Streptococcus agalactiae (Group B Strep) > Escherichia coli > Listeria monocytogenes.
What is the characteristic cerebrospinal fluid (CSF) finding in Guillain-Barré Syndrome (GBS), and why does it occur?
Albuminocytologic dissociation:
- GBS is an immune-mediated demyelinating polyneuropathy. The peripheral nerves and spinal roots are affected, but because GBS is not an infectious or inflammatory CNS disease, there is no significant pleocytosis (increase in WBCs).
What unique clinical signs are associated with meningitis in neonates (< 1 month)?
- Bulging fontanelles
- Irritability
- Poor Feeding
What is the empirical treatment for bacterial meningitis in neonates (<1 month)?
Ampicillin + cefotaxime (avoid ceftriaxone at this age due to biliary slowing and kernicterus)
OR
Ampicillin + gentamicin
OR
Ampicillin + aminoglycoside
- Ampicillin is to provide coverage against Listeria monocytogenes, a gram-positive bacillus with intrinsic resistance to cephalosporins.
- Third-generation cephalosporin (cefotaxime) covers Neisseria meningitidis, aerobic gram-negative bacilli, and most strains of Streptococcus pneumoniae.
- Gentamicin has synergistic effect with penicillins; penicillins disrupt the cell wall, which improves gentamicin entry to the cytosol.
What are the most common causes of bacterial meningitis in infants (1-23 months)?
Streptococcus pneumoniae > Neisseria meningitidis > Streptococcus agalactiae >Haemophilus influenzae > Escherichia coli.
What is the empirical treatment for bacterial meningitis in infants (1-23 months)?
Vancomycin + third-generation cephalosporin (cefotaxime or ceftriaxone).
- Vancomycin covers cephalosporin-resistant Streptococcus pneumoniae.
- Third-generation cephalosporin (ceftriaxone or cefotaxime) covers Neisseria meningitidis, aerobic gram-negative bacilli, and most strains of Streptococcus pneumoniae.
What are the most common causes of meningitis in patients aged 2 to 50 years old?
Streptococcus pneumoniae > Neisseria meningitidis
What are the most common viral causes of meningitis in children and young adults?
Enteroviruses (coxsackievirus) > HSV > Arboviruses (West Nile)
What are the key clinical features of Neisseria meningitidis meningitis?
- Rapid-onset fever, headache, and nuchal rigidity
- Petechial or purpuric rash (classic)
- Hypotension and shock (due to endotoxin-induced sepsis)
- Altered mental status (can progress to coma)
- Disseminated Intravascular Coagulation (DIC)
- Waterhouse-Friderichsen syndrome (adrenal hemorrhage → severe shock)
How is Neisseria meningitidis transmitted and who is at risk?
- Person-to-person via respiratory droplets
- High-risk groups include college dormitory students, military recruits, close household contacts, patients with complement deficiency (C5–C9) → impaired membrane attack complex (Eculizumab & Ravulizumab), asplenic patients (higher risk due to lack of opsonization)
How is Neisseria meningitidis prevented?
Quadrivalent conjugate meningococcal vaccine (MCV4):
- First dose at age 11–12
- Booster at age 16
- Required for college students, military recruits, travelers to endemic areas
Serogroup B vaccine (MenB):
- Given to high-risk individuals (asplenia, complement deficiency, outbreak exposure)
What is the empirical treatment for bacterial meningitis in patients aged 2 to 50 years?
Vancomycin + third-generation cephalosporin (ceftriaxone or cefotaxime)
- Vancomycin covers cephalosporin-resistant Streptococcus pneumoniae.
- Third-generation cephalosporin (ceftriaxone or cefotaxime) covers Neisseria meningitidis, aerobic gram-negative bacilli, and most strains of Streptococcus pneumoniae.
