meningitis%20-%20acute,%20bacterial%20(pediatric)
MENINGITIS - ACUTE, BACTERIAL (PEDIATRIC)
Acute meningitis is the bacterial infection of the subarachnoid space and cerebrospinal fluid that may cause local and systemic inflammatory response.
Common symptoms in newborns are lethargy, fever, seizures, irritability and bulging fontanelle. While in children the common symptoms are fever, nuchal rigidity (incidence increases with age) and altered consciousness.
Meningeal signs are stiff neck, Kernig's or Brudzinski's signs) are not reliably present in infants <6 months of age.
It may also observe the presence of persistent vomiting, changes in behavior or other psychological/neurologic signs.

Meningitis%20-%20acute,%20bacterial%20(pediatric) Diagnosis

Assessment

  • Perform a complete neurologic exam, including a mental status exam if applicable
  • May decide to delay lumbar puncture (LP) if contraindications are noted on assessment [signs of increased intracranial pressure (ICP), severe cardiopulmonary compromise and infection of the skin overlying the LP site]

Look for Signs of Meningeal Irritation

Neck Stiffness

  • Examine the neck for rigidity by gentle forward flexion with the patient in supine position

Kernig Sign

  • Position of patient: Supine, with the hip flexed at 90o
  • Positive when extension of the knee from this position elicits resistance or pain in the lower back or posterior thigh

Brudzinski Sign

  • Position of patient: Supine
  • Positive when passive neck flexion results in flexion of the knees and hips
Contralateral Reflex
  • Position of patient: Supine
  • Positive when passive flexion of one hip and knee causes flexion of the contralateral leg

Look for Signs of Increased Intracranial Pressure

  • Headache
  • Emesis
  • Bulging fontanel or diastasis (widening) of the sutures
  • Ocular movement disorders (eg Abducens nerve palsy)
  • Hypertension with bradycardia
  • Apnea or hyperventilation
  • Altered state of consciousness (eg coma) 
  • Decorticate or decerebrate posturing

Other Signs and Symptoms

Neonates

  • Neonates with bacterial meningitis usually do not have meningismus
  • They can present with temperature instability, jaundice, vomiting, diarrhea, respiratory distress, high-pitched crying, irritability, lethargy, refusal to eat and changes in affect and state of alertness
  • Bulging fontanelle may occur late in the illness
  • Seizures commonly reported among those with group B streptococcal meningitis

Children 1-4 years

  • May also suffer antecedent or concurrent respiratory infections
  • Fever, chills, vomiting, photophobia, severe headache and nuchal rigidity are the most common initial symptoms

Laboratory Tests

Lumbar Puncture (LP) and Cerebrospinal Fluid (CSF) Exams

  • Perform LP promptly and send CSF specimens for exams, to facilitate initiation of appropriate therapy
  • A positive CSF culture is diagnostic of bacterial meningitis
  • Determine if there are contraindications for a STAT LP
    • Thrombocytopenia is a relative contraindication if patient is immunosuppressed
  • CSF formula: Cell count, glucose, protein
  • Extent of CSF abnormalities depend on causative agent

Findings suggestive of bacterial/purulent meningitis:

  • Elevated opening pressure
  • Elevated protein levels
  • Decreased glucose
  • Neutrophilic pleocytosis
  • Elevated lactate levels
Gram Stain and Culture
  • 105 CFU/mL of bacteria should be present for Gram stain to be reliable
Antigen/Antibody Tests
  • Eg pneumococcal bacterial antigen test (BAT), latex agglutination test, cryptococcal antigen latex agglutination system (CALAS), immunochromatographic antigen test
    • Make use of serum containing bacterial antibodies or commercially available antisera directed against capsular polysaccharides of meningeal pathogens
  • BAT is reserved for patients whose initial CSF Gram stain is negative or CSF culture is negative after 48 hours of incubation
    • Pneumococcal BAT have a sensitivity for pneumococcal meningitis between 67%-100% and a specificity of >95%
  • Latex agglutination is a rapid diagnostic tool to determine the causative pathogen
    • Sensitivity varies for each causative pathogen: 78-100% for H influenzae, 22-93% for N meningitidis, and 59-100%f or S pneumoniae
    • Sensitivity decreases when empiric treatment is started before lumbar puncture

Other tests, as warranted:

  • Acid fast bacilli (AFB) smear and tuberculosis (TB) culture, India ink, latex antigen techniques, polymerase chain reaction (PCR), tissue culture, Limulus lysate test, counter immunoelectrophoresis

Blood Cultures (BC)

  • Obtain BC preferably before instituting empiric antibiotic therapy
  • May be done first if with contraindications for a STAT LP
Other Laboratory Exams:
  • Blood urea nitrogen (BUN), serum sodium, chloride, potassium and bicarbonate
  • Urine output and specific gravity
  • Complete blood count and platelet counts
    • In the presence of petechiae, purpura or abnormal bleeding, measure of coagulation function may also be assessed

Imaging

Cranial Imaging [Computed Tomography (CT), Magnetic Resonance Imaging (MRI)]

  • Criteria for performing cranial imaging prior to LP include presence of focal neurologic deficits, new-onset seizures, severe altered mental status (Glasgow Coma Scale <10), and severely compromised immune system (ei transplant patients, HIV-positive)
  • Magnetic resonance imaging with gadolinium enhancement and diffusion-weighted imaging may be used for patients with meningitis secondary to medical devices (eg CSF shunt, CSF drain, intrathecal drug therapy)
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