Meningitis/Encephalitis Flashcards
What type of haemolysis is seen with streptococcus pneumoniae and group b streptococci respectively?
Strep pneumoniae is alpha-haemolytic (partial haemolysis)
Group B streptococci is beta-haemolytic (complete haemolysis)
What are the usual habitats of streptococcus pneumoniae and group b streptococci respectively?
Strep pneumoniae - normal flora of the upper respiratory tract, can be asymptomatically carried in the nasopharynx
Group B streptococci - colonises genital tract and recutum of women, transiently colonise neonates during birth
List major causes of bacterial meningitis according to age group.
Neonates: Group B streptococci, Listeria monocytogenes, E. coli
Infants & Young Children: Haemophilus Influenza
Teenager & Adult: Streptococci pneumoniae, Neisseria meningitidis
Elderly (>65): Streptococcus pneumoniae, Listeria monocytogenes
List major causes of bacterial meningitis according to patient factors.
Decreased cell-mediated immunity (eg in neonates/elderly) - Listeria monocytogenes
Neurosurgery or head trauma - staphylococcus, gram -ve bacilli (Klebsiella pneumoniae, E.coli, pseudomonas aeruginosa)
Fracture of cribriform plate (thinnest part of base of skull) - Streptococci pnaemoniae
Viral meningitis is the most common cause of meningitis. Out of this subgroup, which type of virus is the most common cause in immunocompetent adults?
Enteroviruses
Characteristics of acute bacterial meningitis?
- The pia-arachnoid is congested with polymorphs
- A layer of pus forms
- This may organise to form adhesions, causing cranial nerve palsies and hydrocephalus
- Cerebral oedema occurs in any bacterial meningitis
Characteristics of bacterial meningitis due to chronic infection?
- The brain is covered in a viscous grey-green exudate with numerous meningeal tubercles
- Adhesions are invariable
- Cerebral oedema occurs in any bacterial meningitis
Characteristics of viral meningitis?
- There is a predominantly lymphocytic inflammatory cerebrospinal fluid (CSF) reaction without pus formation, polymorphs or adhesions
- There is little or no cerebral oedema unless encephalitis develops
Clinical features of meningitis?
Triad of fever, neck stiffness and headache
Photophobia, vomitting
Clinical features of acute bacterial meningitis?
Typically sudden-onset
Rigors
High fever
Meningoccocal septicaemia would present with purpuric non-blanching rash
Investigations for meningitis?
Bloods, ABG, Blood culture, CT head
Lumbar puncture for CSF analysis (LP should be set up ideally within an hour on arrival at hospital, and treatment commenced immediately)
CSF characteristics in bacterial and viral meningitis?
How to manage viral meningitis?
- Treatment is generally supportive - self-limiting condition lasting 4–10 days
- Acyclovir can be used to treat suspected or confirmed HSV or VZV infection
When meningococcal meningitis is diagnosed clinically by the petechial rash, should IV antibiotics be given before blood culture returns?
Yes, it should be given immediately
How to manage bacterial meningitis in adults?
How to manage bacterial meningitis in children?
