Meningitis

• Causes
  • 0-2 months – Group B strep, E Coli, Listeria
  • Age > 2 months – S.pneumoniae, N.meningitidis, HiB ( unimmunised children). Occasionaly Group B strep, E Coli
  • bimodal age distribution
    • 0-4 year olds and
    • 15-25 year olds

• Neisseria meningitidis
  • significant decline since 2004 
  • Serogroup C Meningococcal vaccination programme
  • serogroup B now comprises 78% of bacterial isolates
  • case fatality rate 11.6%
• Consider other pathogens in those who have anatomical abnormalities of the CNS, ventricular shunts, immunosuppressed children and those who have a history of travel. 
• Encephalitis can be caused by:
  • Enterovirus
  • HSV
  • Other herpes viruses (EBV, CMV, HHV6, VZV)
  • Arboviruses.
  • Less commonly, encephalitis can be caused by bacteria, fungi or parasites.
• 33% long-term complications
  • learning academic difficulties
  • hearing impairment (7%)
  • neurologic (12.2%)
  • behavioral (14.8%) and motor (10.4%) deficits
• vaccines covering Serotype B now in Phase 1 trials

Differentials for Headache and fever:

• Intracranial infections:
  • Meningitis 
  • Encephalitis 
  • Sinusitis 
• Systemic infections / other organs
  • Influenza 
  • LRTI & sepsis
  • UTI sepsis 
  • EBV 
  • Infectious endocarditis 
• Exotic infections from her travel
  • Dengue 
  • Malaria 
  • Typhoid 
• Regional Australia infections
  • Q fever 
  • Barmah forest virus 
• Noninfections
  • Subarachnoid haemorrhage 
  • Giant cell arteritis in the elderly adult 

History

• may mimic common viral infections in early phase 
• Fever
• Immunisation history
• Recent antibiotic exposure
• Infant:
  • minimal or non-specific symptoms
  • irritability
  • lethargy or drowsiness
  • poor feeding
  • hyper or hypotonia
  • vomiting and diarrhoea
  • temperature instability
• Child, any of the above and/or:
  • headache
  • pholophobia
  • nausea
  • altered conscious state
• Preceding URTI may be present
• Encephalitis -> Features of altered mental slate can be subtle and depend on the affected region of the brain:
  • unusual behaviour
  • confusion
  • personality change
  • emotional !ability
• Seizures
• Medical condition that may predispose child to meningitis
  • CNS anatomical abnormality or shunt
  • Immunosuppression
  • immunodeficiency

Examination

• Febrile, irritable, lethargy, poor feeding
• Fontanelle in children- bulging
• Neck stiffness
  • may or may not be present (not a reliable sign in young children)
• Kernig sign:
  • Child is supine
  • One hip and knee are flexed to 90 degrees by the examiner
  • The examiner then attempts to passively extend child’s knee
  • Positive if there is pain along spinal cord, and/or resistance to knee extension
• Brudzinski sign:
  • Child is supine with legs extended
  • The examiner grasps child’s occiput and attempts neck flexion
  • Positive if there is reflex flexion of child’s hips and knees with neck flexion  
• Petechial or purpuric rash
  • any part of body
  • early stage may resemble viral exanthema
  • may progress rapidly
  • do not rely on the presence of purpura to make the diagnosis
  • frequently absent in early stages of overwhelming sepsis
  • Purpuric rash is a late sign suggestive of meningococcal sepsis

Red flag features in Red

Meningitis	Encephalitis
History Fever Immunisation history Recent antibiotic exposure Infant:  = minimal or non-specific symptoms = irritability l= ethargy or drowsiness = poor feeding = hyper or hypotonia = vomiting and diarrhoea = temperature instability Child, any of the above and/or: = headache = photophobia = nausea = altered conscious state   Preceding URTI may be present Seizures Medical condition that may predispose child to meningitis (eg CNS anatomical abnormality or shunt, immunosuppression, immunodeficiency)	History Fever Features of altered mental state can be subtle and depend on the affected region of the brain: = unusual behaviour = confusion = personality change = emotional lability Seizures (common) Headache Nausea and vomiting Consider other causes of encephalopathy eg ADEM, toxins or metabolic
Examination Full fontanelle High-pitched cry  Fever or hypothermia Apnoea Neck stiffness (may be absent in infants) Focal neurological signs  Purpuric rash is a late sign suggestive of meningococcal sepsis Pain and involuntary effort to reduce meningeal “stretch” eg Kernig and Brudzinski signs	Examination Focal neurological signs

Investigations

• Febrile unwell infant should have – FBC, BSL, lactate, CRP, blood culture, urine MCS
• Depending on age/symptoms – LP or CXR
• CSF – high WCC, possibly RBCs, glucose < 60% of serum, incresed protein
• MCS of CSF
• Lumbar puncture
  • Contraindicated if there’s
    • focal neurological signs 
    • new or prolonged seizures 
    • rapidly decreasing GCS (which could be argued in the this patient) 
    • papilloedema 
    • on anticoagulants 
    • known to be immune deficient 
• CT brain
  • Do BEFORE LP if there’s signs of raised intracranial pressure (ICP)
  • Also CT Head first if:
    • (1) new onset seizures
    • (2) immunocompromised
    • (3) GCS < 10
    • (4) focal neurological signs in keeping with a space occupying lesion.
    • (5) encephalitis
    • (6) focal neurological signs
    • (6) diagnostic uncertainty (eg to look for a mass)
  • Is not routine in meningitis but is used to look for complications eg abscess, thrombosis
  • Normal head CT does not exclude raised ICP and should not influence the decision to perform an LP
  • MRI will provide more detailed information to guide diagnosis, but may require general anaesthetic

Treatment

• Pre-hospital antiboitics if transfer will de delayed or if developing purpura suggestive of meningococcal sepsis
• Pre-hospital – ceftriaxone 50mg/kg or Benxylpenicillin
• IV ceftriaxone 50mg/kg BD
• Neonate – cover Listeria
• Children > 2 months – consider dexamethasone 0.15mg/kg
• If encephalitis is suspected on examination then give : Aciclovir 

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 12H or cefotaxime 50 mg/kg (max 2 g) IV 6H Add Vancomycin if Gram-positive cocci on Gram stain	0.15 mg/kg (max 10 mg) IV 6H for 4 days
Encephalitis
	HSV  Mycoplasma pneumoniae Other viruses: EBV, CMV, HHV6, Influenza Arboviruses	Aciclovir 20 mg/kg IV 12H (<30 weeks gestation), 8H (>30 weeks gestation to <3 months corrected age) 500 mg/m2  or 20 mg/kg IV 8H (3 months–12 years) 10 mg/kg IV 8H (>12 years)Consider adding azithromycin	Not advised

Complications

• Subdural effusion, empyema, cerebral abscess – consider MRI
• Hearing impairment
• Neurodevelopmental impairment
• Multi-organ involvement – due to pathogen or secondary to septic shock
• Venous sinus thrombosis
• Seizures, epilepsy
• Permanent neurological defect
• Hydrocephalus

Follow up

• Should have formal audiology assessment 6-8 weeks
• Monitor development

PUBLIC HEALTH CONSIDERATIONS

• Neiserria meningitides – requires droplet precautions
• post-exposure prophylaxis needed for close contacts if <24h treatment with appropriate antibiotics
• Notification
  • All cases of presumed or confirmed Neisseria meningitidis disease should be urgently notified to the Department of Human Services by telephone
  • Haemophilus influenzae type b, and Streptococcus pneumoniae are also notifiable diseases.
• Contact chemoprophylaxis  

Organism	Those requiring prophylaxis	Antibiotic
N.meningitidis	Index Case (if treated only with penicillin) and all intimate, household or daycare 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.	Rifampicin 10 mg/kg po 12 hourly (600 mg) for 2 days
		Infants < 1 month of ageRifampicin 5 mg/kg po 12 hourly for 2 days
		Pregnancy / contraindication to RifampicinCeftriaxone 125 mg (<12 y) / 250 mg (>12 y) mg im as a single dose or Ciprofloxacin 500 mg po as a single dose
S.pneumoniae	No increased risks to contacts	Nil
H influenzae type b	Index Case and all household contacts if household includes other children < 4 years of age who are not fully immunised. Index Case and all household contacts in households with any infants <12 months of age, regardless of immunisation statusIndex Case and all household contacts in households with a child 1 to 5 years of age who is inadequately immunised Index Case and all room contacts including staff in a child care group if Index Case attends > 18 hours / week and any contacts < 2 years of age who are inadequately immunised. (NB. Inadequately immunised children should be immunised.)	Rifampicin 20 mg/kg po as a single daily dose (600 mg) for 4 days
		Infants < 1 month of ageRifampicin 10 mg/kg po daily for 4 days
		Pregnancy / contraindication to RifampicinCeftriaxone 125 mg (<12 y) / 250 mg (>12 y) mg im as a single dose

Prevention

• Vaccination  – ACWY and Bexero
• Address risk factors
  • Living in dormitory or military barracks
  • Tobacco use or passive Tobacco exposure
  • Recent Upper Respiratory Infection/splenectomy/HIV