Meningitis

1. Epidemiology
   1. asymptomatic nasal carriage in 10% population
   2. invasive Meningococcal disease usually presents as meningitis or septicaemia
   3. septicaemia particularly severe disease with greater mortality
   4. bimodal age distribution
      1. 0-4 year olds and
      2. 15-25 year olds
   5. Organisms to consider in infants less than 2 months of age include those listed above and the following:
      1. Group B streptococcus
      2. E. coli and other Gram-negative organisms
      3. Listeria monocytogenes
   6. commonest organisms causing bacterial meningitis in children over 2 months of age are:
      1. Streptococcus pneumoniae 
      2. Neisseria meningitidis 
      3. Haemophilus influenzae type B (in unimmunised children)
   7. Neisseria meningitidis
      1. significant decline since 2004 
      2. Serogroup C Meningococcal vaccination programme
      3. serogroup B now comprises 78% of bacterial isolates
      4. case fatality rate 11.6%
   8. Consider other pathogens in those who have anatomical abnormalities of the CNS, ventricular shunts, immunosuppressed children and those who have a history of travel. 
   9. Encephalitis can be caused by:
      1. Enterovirus
      2. HSV
      3. Other herpes viruses (EBV, CMV, HHV6, VZV)
      4. Arboviruses.
      5. Less commonly, encephalitis can be caused by bacteria, fungi or parasites.
   10. 33% long term complications
       1. Learningac ademic difficulties
       2. hearing impairment (7%)
       3. neurologic (12.2%)
       4. behavioural (14.8%) and motor (10.4%) deficits
   11. vaccines covering Serotype B now in Phase 1 trials

2. Risk factors
   1. Neonates:
      1. Prematurity
      2. ↓ Birth weight 
      3. Delivery complications 
      4. Maternal group B streptococcal
      5. colonization
      6. Maternal infections such as HSV
   2. Older children:
      1. ↓ Family income
      2. Daycare
      3. Head trauma
      4. Splenectomy
      5. Chronic disease, e.g. HIV. Other Infections

3. Assessment
   1. Clinical presentation
      1. may mimic common viral infections in early phase
      2. symptoms progress rapidly
      3. Infants with meningitis frequently present with non-specific symptoms such as fever, irritability, lethargy, poor feeding, vomiting and diarrhoea
      4. Older children may complain of headache or photophobia
      5. Seizures
      6. Prior antibiotics – clinical presentation may be altered by prior use of antibiotics.
      7. in babies
         1. fever
         2. tachypnoea
         3. rash
         4. vomiting
         5. irritability
         6. poor feeding
         7. drowsiness
         8. pallor
         9. Neck stiffness may or may not be present (not a reliable sign in young children)
         10. Kernig’s sign: hip flexion with an extended knee causes pain in the back and legs
      8. in children
         1. fever
         2. chills
         3. rash
         4. headache
         5. neck stiffness
         6. vomiting
         7. muscle aches and pains
         8. abdominal pain
      9. characteristic rash
         1. purpuric
         2. any part of body
         3. early stage may resemble viral exanthema
         4. may progress rapidly
         5. do not rely on the presence of purpura to make the diagnosis
         6. frequently absent in early stages of overwhelming sepsis
      10. prehospital presentation with leg pain and cool peripheries early symptom before classic rash, fever

Kernig sign:

1. Child is supine
2. One hip and knee are flexed to 90 degrees by the examiner
3. The examiner then attempts to passively extend child’s knee
4. Positive if there is pain along spinal cord, and/or resistance to knee extension

Brudzinski sign:

1. Child is supine with legs extended
2. The examiner grasps child’s occiput and attempts neck flexion
3. Positive if there is reflex flexion of child’s hips and knees with neck flexion  

4. Investigations
   1. Lumbar puncture (LP)
      1. Sterilisation of the CSF can occur within 2 hours after a dose of Ceftriaxone 50 mg/kg/dose (2g) iv 12H /Ceftriaxone for N. meningitidis and within 4 hours for S. pneumoniae
   2. Full blood count/differential
   3. Glucose, urea and electrolytes
   4. Blood cultures nasopharyngeal swab
5. other possible investigations:
   1. coagulation screen
   2. blood gases
   3. joint or rash aspirate

6. Management
   1. Antimicrobials

Antibiotics must not be delayed for more than 30 minutes after the decision to treat is made
Antimicrobial recommendations may vary according to local antimicrobial susceptibility patterns; please refer to local guidelines

Age group	Common organisms	Empiric antibiotic	Dexamethasone
Meningitis
0–2 months	Group B streptococci (GBS), Escherichia coli, Listeria monocytogenes (rare)	Benzylpenicillin 60 mg/kg IV 12H (week 1 of life) 6–8H (week 2–4 of life) 4H (>week 4 of life) and  Cefotaxime 50 mg/kg (max 2 g) IV 12H (week 1 of life) 6–8H (week 2–4 of life) 6H (>week 4 of life)	Not advised
≥2 months	N meningitidis, HiB, S pneumoniae	Ceftriaxone 50 mg/kg (max 2 g) IV BD or  Cefotaxime 50 mg/kg (max 2 g) IV QID Add Vancomycin if Gram-positive cocci on Gram stain	0.15 mg/kg (max 10 mg) IV 6H for 4 days
Encephalitis
	Mycoplasma pneumoniae HSV EBV CMV HHV6 Influenza Arboviruses	Aciclovir <30 weeks gestation= BD =20 mg/kg IV >30 weeks gestation to <3 months corrected age = TDS = 20 mg/kg IV 3 months–12 years = TDS = 20 mg/kg IV >12 years = TDS = 10 mg/kg IV 8H Consider adding azithromycin	Not advised

2. Steroids
   1. Current evidence suggests that steroids may reduce the risk of hearing loss in bacterial meningitis.
   2. Consider giving Dexamethasone to children > 2 months of age 15 minutes prior to parenteral antibiotics or, if this is not possible, within one hour of receiving their first dose of antibiotics: 0.15mg/kg IV. 
   3. Consider giving steroids at the time of lumbar puncture if the clinical suspicion of meningitis is high.
   4. Steroids should be ceased if a decision is made to cease antibiotic treatment for meningitis before 4 days (eg CSF microscopy not suggestive, CSF cultures negative at 48 hours).
   5. Steroids are not recommended in neonates due to concern regarding effects on neurodevelopment

3. fluid resuscitation
   1. Careful management of fluid and electrolyte balance is important in the treatment of meningitis. 
   2. Over or under hydration are associated with adverse outcomes. 
   3. Many children have increased antidiuretic hormone secretion, and some will have dehydration due to vomiting, poor fluid intake or septic shock. 
   4. Hyponatramia occurs in about one third of children with meningitis, and may be due to increased ADH secretion, increased urine sodium losses, and excessive electrolyte-free water intake or administration
   5. Fluid should be isonatraemic
   6. Correct Hypovolemia with 20 mL/kg boluses 0/9%
   7. Maintenance
      1. Plasma-Lyte 148 + 5% Glucose
      2. 0.9% sodium chloride + 5% Glucose
   8. consider ICU admission

(https://www.rch.org.au/clinicalguide/guideline_index/Fluid_management_in_meningitis/)

Complications

• Persistent fever after 4–6 days of treatment consider:
  • nosocomial infection
  • subdural effusion or empyema
  • cerebral abscess or parameningeal foci of ongoing infection
  • inadequate treatment
• Hearing impairment
• Neurodevelopmental impairment
• Multi-organ involvement due to primary pathogen or secondary to septic shock (eg hepatic or cardiac)
• Venous sinus thrombosis
• Seizures, subsequent epilepsy
• Permanent focal neurological deficit
• Hydrocephalus

Chemoprophylaxis for contacts

• Index case (if treated only with penicillin) and all intimate household or day care contacts who have been exposed to index case within 10 days of onset.
• Any person who gave mouth-to-mouth resuscitation to the index case
• 3 choices:
  • Rifampicin – 2 day course, contraindicated in pregnancy and liver disease
  • Ciprofloxacin > 12years old, single dose
  • Ceftriaxone IM – drug of choice in pregnant women

Lumbar Puncture

1. It is preferable to obtain a CSF specimen prior to antibiotic administration, however this should not be unduly delayed in a child with signs of meningitis or sepsis
2. Do not do a lumbar puncture if the child is so sick that you will give antibiotics for meningitis even if the CSF is normal on microscopy.
3. Indications
   1. Suspected meningitis or encephalitis
   2. Suspected Sub-arachnoid haemorrhage with a normal CT
4. Contraindications
   1. The clinical findings that suggest you should give dexamethasone and  antibiotics  immediately, and delay lumbar puncture for 1-2 days until the child is improving are:
      1. Coma: absent or non-purposeful response to painful stimulus – squeeze ear-lobe firmly for up to 10 seconds. A child over 3 months of age should push you away and seek a parent. 
      2. Signs of raised intracranial pressure: eg drowsy, diplopia, abnormal pupillary responses, unilateral or bilateral motor posturing or papilloedema (NB papilloedema is an unreliable and late sign of raised ICP in meningitis; a bulging fontanelle in the absence of other signs of raised ICP, is not a contraindication). 
      3. Cardiovascular compromise/ shock 
      4. Respiratory compromise 
      5. Focal neurological signs or seizures 
      6. Recent seizures (within 30 minutes or not regained normal conscious level afterwards). 
      7. Coagulopathy/thrombocytopenia 
      8. Local infection (in the area where an LP would be performed) 
      9. The febrile child with purpura where meningococcal infection is suspected
   2. Assessment prior to LP for contraindications?
      1. CT Scans if focal neurological signs
      2. CT Scans are not helpful in most children with meningitis.
      3. A normal CT scan does not tell you that the patient does not have raised ICP.
      4. Herniation may occur even in the presence of a normal scan.
      5. Don’t delay antibiotics whilst waiting for a CT
5. Complications
   1. Failure to obtain a specimen / need to repeat LP/ Traumatic tap (common)
   2. Post-dural puncture headache (fairly common) – up to 5-15%
   3. Transient/persistent paresthesiae/numbness (very uncommon)
   4. Respiratory arrest from positioning (rare)
   5. Spinal haematoma or abscess (very rare)
   6. Tonsillar herniation (extremely rare in the absence of contraindications above)