Meningitis and Encephalitis Flashcards
What is meningitis and encephalitis?
Meningitis = inflammation of meninges
Encephalitis = inflammation of branc parenchyma
What barriers exist to prevent CNS infection?
Physical barriers - skull, vertebrae, meninges
Blood brain barrier
How can pathogens cause CNS infection?
BArriers must be disrupted
- Capsule - neurotropic virulence factor
- Bloodstream infection combined with immature BBB
- Trauma - disruption in physical barriers
What is the classic triad of meningitis presentation?
- Fever
- Altered mental state (confusion, drowsiness)
- Neck stiffness
What three symptoms are seen in meningism?
Headache + photophobia + neck stiffness
Sequelae of meningitis?
- Raised ICP due to cerebral oedema → headache, nausea, vomiting
- Neurological signs → seizures, hemiparesis, nerve palsies
Is recovery common in meningitis?
Yes. complete recovery is very common
CLinical features of encephalitis?
Much the same as meningitis
- Headache, fever, nausea
- Altered mental status → confusion, drowsiness
- Seizures
- Focal neurological abnormalities → hemiparesis, herve palsies, speech/movement disorders
Which is more likely to cause permanent neurological sequelae - meningitis or encephalitis?
Encephalitis
Causes of meningitis: bacterial (3), viral (1), fungal (1)?
Bacterial:
- Neisseria meningitidis
- Streptococcus pneumoniae
- Listeria monocytogenes
Viral:
- Enteroviruses
Fungi:
- Cryptococcus
2 viral causes of encephalitis?
- Herpes simplex virus 1
- Arboviruses - JEV, West Nile, Murray valley
Majority of encephalitis is ____ and meningitis is _____
Encephalitis = viral
Meningitis = bacterial
Which bacteria are often asymptomatically carried in nasopharynx?
Neisseria meningitidis and streptococcus pneumoniae.
Neisseria meningitidis, streptococcus pneumoniae and listeria monocytogenes - Gram stain and treatment?
Neisseria meningitidis
- Gram neg - pink stain
- IV ceftriaxone
Streptococcus pneumoniae
- Gram positive - purple stain
- IV ceftriaxone
Listeria monocytogenes
- Gram positive - purple stain
- Not treatable by ceftriaxone
- Most common on ends of age spectrum - neonates and older adults
Is there a meningococcal vaccine?”
Yes - routine in Aus - serogroup A/C/W/Y
Prognosos of Neisseria and Streptococcus CNS infection with treatment
Still have 15-20% mortality with treatment of both.
Which bacterial CNS infectio may result in pregancy loss?
Listeria monocytogenes
Common causes of meningitis and neonate and why?
BActerial meningitis is most common in first month of life - underdeveloped immune system and BBB
Causes:
- Strep agalactiae
- E. coli
- Enterobacteriaceae
Commonest cause of viral meningitis and treatment?
Enteroviruses
No specific treatment.
Two subtypes of fungal cause of meningitis
Crytpcoccus neoformans and gattii
Which demographic is fungal meningitis most often seen
Immunocompromised
What is the most common cause of viral encephalitis?
HSV-1
What is the worst kinda of viral encephalitis?
Arboviral - Murray Valley, West Nile, JEV
Getting encephalitis from arboviruses is rare, but is really bad if you do get it
- 33% mortality
- Permanently neurological abnormalities
Treatment for HSV-1 encephalitis?
Antivirals - aciclovir
Still 10%-30% mortality
Sequelae of HSV-1 encephalitis?
- Disseminated infection
- Cognitive impairment
Gold standard of meningitis and encephalitis diagnosis?
Lumbar puncture with CSF analysis.
CSF tested for:
- protein and glucose
- Microscopy, culture and sensitivities (MC&S)
- PCR
ROle of CT and MRI in meningitis/encephalitis diagnosis?
CT
- Looks normal in both conditions
- Used to exclude other conditions
MRI
- More sensitive
What can a gram stain tell you about causes of meningitis?
Gram negative diplococci - Neisseria meningitis
Gram positive diplococci - Streptococcus pneumoniae
Gram postivie bacilli - Listeria monocytogenes
Findings of MC&S?
Normal CSF is clear, high WCC will make it turbid.
Raised WCC = pleiocytosis
Neutrophilic pleiocytosis = bacterial cause
Mononuclear pleiocytosis = viral cause
What is the definitive way to diagnose viral meningitis/encephalitis?
PCR
