ID: Meningitis & Encephalitis Flashcards
What are the classic traid of clinical features of meningitis?
Fever
Neck stiffness
Altered mental state (confusion or drowsiness)
What are the sequelae of meningitis?
- Raised intracranial pressure
- Due to cerebral oedema
- headache, nausea, vomiting, papilloedema
- Seizures
- Cranial nerve palsies
- Sensorineural hearing closs
What are the clinical features of encephalitis?
- Headache
- Fever
- Nause and vomiting
- Altered mental ste
- Seizures
-
Focal neurological abnormalities (depends on site of brain involvement)
- Weakness
- Nerve palsies
- Hemiparesis
- Speech or movement disorders
- Abnormal reflexes
- Personality changes
What are the common causes of bacterial meningitis by age group?
- Neonates:
- Group B Strep
- E. coli
- Gram negative bacilli
- Listeria
- Children:
- N. meningiditis
- S. pneumoniae
- H. influenzae serotype B
- Young adults
- N. meningiditis
- S. pneumoniae
- Older adults
- S. pneumoniae
- N. meningitidis
- Listeria
What is therapy for neisseria meningitidis (and same for streptococcus pneumoniae)?
- Benzylpenicillin
If allergic:
- Ceftriaxone
What is treatment for Listeria monocytogenes?
Listeria is intrinsically resistant to cephalosporins so use benzylpenicillin or amoxycillin
Why are neonates susceptible to meningitis? Which pathogens most common?
Immune system and blood-brain barrier both immature
Common causes:
- Streptococcus agalctiae (group B strep)
- E. coli
- Klebsiella, Serratia, Citrobacter (other Enterobacteriaciae)
What are the causative agents of meningitis following taruma or neurosurgical procedures?
- Skin organisms
- staph aureus
- coagulase-netative staphylococci
- Commensals and environmental gram-negs
- e. coli, klepsiella, enterobacter
- Oropharyngeal organisms
- step pneumoniae
- Commensal or environmental fungi
- Candida spp
What are the 2 modes of pathogenetic spread that willd cause brain abscesses?
1) Direct spread (from de novo infection)
- otitismedia
- sinusitis
- dental infection
2) Haematogenous spread
- endocarditis
- respiratory, intra-abdominal, skin infections
What sort of lesions would we expect to see in a brain abscess on CT scan?
Ring enhancing lesion - very little blood going into abscess full of dead cells
What are some rare causes of bacterial CNS infection?
- Mycoplasma pneumoniae
- Syphilis (Treponema pallidum)
- tertiary syphilis
- Lyme disease (Borrelia burgdorferi)
- Rickettsia
- Q fever
- Bartonella (cat scratch)
What is by far the most common cause of viral meningitis?
Enterovirus (85-95%)
Numerous serotypes:
- Enterovirus 68-71
- Echovirus 1-33
- Coxsackievirus 1-24
- Poliovirus 1-3
Most infections cause a mild, self-limiting viral illness
In children, see hand,foot, and mouth disease.
What are other common causes of viral meningitis?
- Herpesvirus
- HSV2 - selflimiting - usually with primary genital infection
- VZV - may cause mild meningitis during reactivation
- Mumps
- occurs in 10-30% of mumps patients
What is the most common cause of viral encephalitis?
HSV1 - may occur with primary infection or reactivation
Directe dtherapy is IV aciclovir
Treated morality is 10-30%
May cause permanent cognitive impairment
What are the different arboviruses that causes encephalitis (with mosquito vector)?
- Flaviviruses
- Aus
- MVE
- Kunjin
- Southern Asia
- Japanese encephalitis
- Widespread
- West nile
- Dengue
- Zika - in utero
- Aus
- Alphaviruses
- “old world” are arthritogenic - RRV, BFV
- “new world” are neurotropic
