Epidemiology  

1. 10,000 cases of bacterial meningitis each year in United States

2. Mortality of  5-15% and morbidity higher if neurologic impairment evident at time of presentation.
    a. Among bacterial paathogens, pneumococcal meningitis has the highest mortality adn morbidity
    b. Neurologic sequelae- hydrocephalus, sensory/motor deficits, seizures, hearing loss.

3. Changes in incidence related to immunizations for Hemophilus influenza and S. pneumonia.

Risk Factors

1. < 1 year old ( highest in newborns)

2. Sick contacts including daycare

3. Communicating anatomical defects with CNS

4. Immunodeficiencies

5. Unimmunized against H. influenza and S. pneumonia

Pathogenesis

1. Attachment and colonization of the nasalpharyngeal mucosal epithelium

2. Invasion of adjacent intravascular space (bloodstream)

3. Transport of bacteria to the CSF

4. Survival and replication in the CSF

5. Immune response by the host with resultant migration of neutrophils

6. End result is cerebral edema, decreased arterial flow to the brain, vasculitis and thrombosis of blood vessels and resultant ischemia.

Common Pathogens

1. Streptococcus pneumonia

2. Neiserria meningitidis

3. Hemophilus influenza

4. Neonates and young infants- Group B Streptococcus, Listeria monocytogenes, Escherichia coli

Clinical Presentation

1. History of URI

2. Majority of patients have fever (> 80%)

3. Nausea, vomiting, poor feeding

4. Headache, change in level of alertness

5. Seizure (20%)

6. Apnea/cyanosis/respiratory distress

7. Physical findings

      a. Lethargy

      b. Bulging AF

      c. Stiff neck, + Kernigs, and Brudzinski signs

     d. Petechial rash (most often with N. meningitides)

     e. Evidence of increased intracranial pressure- increased BP, papilledema, and 6th nerve palsy

     f. Evidence of dehydration secondary to vomiting

Diagnosis

1. CSF with increase of neutrophils, elevated protein, glucose < half of peripheral glucose, + gram stain and culture
            a. Tube #1 Culture, and gram stain
            b. Tube #2 Glucose and Protein
            c. Tube #3 Cell count
            d. Tube #4 Hold for  other tests such as PCR if indicated
            e. Normal cell count
                1. neonates- term 0-20
                2. > 4 weeks- 0-5
             f. Protein
                1. term neonate- < 100
                2. older than 4 weeks- <45
            g. Glucose- Normal > 50% of serum glucose.

2. Elevated opening pressure- usually less than 15 cm 

3. Positive blood culture

4. There may be evidence of electrolyte disturbances secondary to vomiting, poor intake, and SIADH.

5. CBC- looking for anemia, high or low wbc with increased neutrophiles and bands, platelet count

6. Serum glucose to compare to CSF glucose.

7. CT- usually not indicated unless there are focal findings on neurologic examination

Treatment

1. Neonates- Ampicillin and Gentomycin

2. Infants -18 years - Ceftriaxone and Vancomycin (coverage for S. pneumonia resistant to Penicillin and Cephalasporins). Adjust antibiotics after get culture and sensitivities

3. Dexamthasone prior to antibiotic treatment is controversial

How to Follow Patients with Meningitis

1. Frequent physical examinations

     a. Evaluate for increased intracranial pressure-blood pressure, pulse, eye movements, fundoscopic exam for papilledema, head circumference, breathing pattern

     b. Hydration status- presence of dehydration secondary to poor intake or vomiting. There may be fluid retention secondary to inappropriate secretion of ADH. This will result in edema, increased weight, and decreased urine output

     c. Fever may persist for 7 days or longer. May need to check for other sites of infections including bone, joints, urinary tract, and pneumonia.

     d. Evaluate level of consciousness

     e. Assess exposure and risks of close contacts (household, daycare, school, hospital personnel) and need for prophylaxis (Redbook 2003)

Complications

1. Seizures, brain abscess, stroke, subdural empyema and effusions, stroke.

2. Hearing deficits- should be assessed on all patients following treatment

3. Loss of milestones

4. Cerebral palsy

5. Mental retardation

6. Cortical blindness

7. School problems.

References

1. 2009 Redbook

2. Willoughby R. and Polack F. Meningitis: What's new in diagnosis and management Contemporary Pediatrics September 1998

3. Wubbell L and McCracken G Management of Bacterial Meningitis 1997 Pediatrics in Review March 1998

4. Negrini B Kelleher K, Wald E. Cerebrospinal Fluid Findings in Aseptic Versus Bacterial Meningitis. Pediatrics 2000:105;316

5. Kanegaye JT. Lumbar Puncture in Pediatric Bacterial Meningitis; Defining the Time Interval for Recovery of CSF Pathogens After Parental Antibiotic Treatment. Pediatrics 2001 Nov;108;1169

6. Garges H. et al. Neonatal Meningitis: What is the Correlation  Among Cerebrospinal Fluid Cultures, Blood Cultures, and Cerebrospinal Fluid Parameters.  Pediatrics April 2006

7. Gardner, P. Prevention of Meninogococcal  Disease.  NEJM Oct 5, 2006

8. Mann K. and Jackson MA. Meningitis.  Pediatrics in Review December 2008  

9. Kestenbaum e tal. Defining Cerebrospinal Fluid White Blod Cell Count Reference Values in Neonates and Young Infants.  Pediatrics. February 2010