meningitis Flashcards
what is meningitis
disease caused by inflammation of the meninges
what is meningism
clinical signs and symptoms suggestive of meningeal irritation
signs and symptoms of meningitis in older children
- fever
- headache
- photophobia
- neck stiffness - nuchal rigidity
raised ICP:
- N+V
- reduced GCS
- seizures
- focal neurological deficits
signs and symptoms of meningitis in young infants
- fever/hypothermia
- poor feeding
- vomiting
- lethargy
- irritability
- resp distress
- apnoea - pause in breathing for at least 20s, signs of significant resp distress and reduced resp drive
- bulging fontanelle - raised ICP
signs and symptoms of meningitis in young infants
- fever/hypothermia
- poor feeding
- vomiting
- lethargy
- irritability
- resp distress
- apnoea - pause in breathing for at least 20s, signs of significant resp distress and reduced resp drive
- bulging fontanelle - raised ICP
clinical signs of meningitis
- nuchal rigidity - palpable resistance to neck flexion
- Brudzinski’s sign - hips and knees flex on passive flexion of the neck
- Kernig’s signs - flex hip and knee to 90 degrees, pain of passive extension of the knee
causes of child meningitis
- bacterial - 4-18%
- viral - mainly enterovirus, 54-88%
- fungal - neonates, immunocompromised
- unknown/aseptic - 40-76%
bacterial meningitis - causative organisms in neonates (<1m)
group B streptococcus
Escherichia coli
Listeria monocytogenes
bacterial meningitis - causative organisms in older infants and children
Streptococcus pneumoniae
Neisseria meningitidis
Haemophilus influenzae type B- uncommon now following vaccination
what type of bacterial is Haemophilus influenzae
small
non-motile
gram -ve
coccobacillus
where is H influenzae carried
nasopharyngeal carriage
what is encapsulated H. influenzae and why is it important
- resist phagocytosis and complement mediated lysis
- 6 serotypes (a-f)
- Hib - main cause of invasive H. influenzae infection
- bacteraemia, meningitis, epiglottitis, pneumonia
- RF - asplenia, sickle cell disease, antibody deficiency
non-encapsulated H. influenzae
- what does it lead to
aka non typeable H. influenzae (NTHI)
- otitis media and sinusitis
- invasive infection is rare
what meningococcal serotype causes the majority of invasive meningococcal disease
B
what type of bacteria is Neisseria meningitidis
gram -ve diplococcus
carriage and transmission of Neisseria meningitidis
humans are the only natural host
nasopharyngeal carriage
transmission via resp secretions
infection often follows URTI
structure of Neisseria meningitidis
polysaccharide capsules
- capsule composition determines serogroup e.g. A, B, C, W, Y
endotoxin production (LPS) - this is why it can leading to overwhelming sepsis
risk factors for invasive meningococcal disease
- <1y, 15-24y/o
- unimmunised
- crowded living conditions
- household or kissing contact
- cigarette smoking (active or passive)
- recent viral/mycoplasma infection
- complement deficiency
features of invasive meningococcal disease
- meningitis
- sepsis
- 15% have isolated featrues of meningitis
- 25% isolated sepsis
- 60% have features of both
rash in invasive meningococal infection
starts off as a blanching maculopapular rash
progresses to petichiae or purpura
purpura fulminans - purpura coaslesce together to form bruise like lesions (poor tissues perfusion and can lead to necrosis)
prognosis of meningococal disease - mortality and significant long term sequelae
rapidly progressive
case fatality 5-15%
- 50% of deaths in 1st 12h
- 80% of deaths in 1st 48h
significant long term sequelae
- amputation 14%
- scarring 48%
- hearing loss
- cognitive impairment/epilepsy
what type of bacteria is streptococcus pneumoniae (pneumococcus)
gram +ve
lancet shaped
diplococcus
facultative anaerobe
capsule in streptococcus pnuemoniae
polysaccharide capsule
- inhibits neutrophil phagocytosis
- inhibits complement mediated cell lysis
