CNS infections Flashcards
What are the 2 main infections of the CNS?
Meningitis
Encephalitis
What is meningitis?
Serious infection of the meninges, the outer membranes covering the brain and spinal cord
What are some of the classifications of meningitis?
Acute pyogenic (Bacterial)
Acute aseptic
Acute focal suppurative
Chronic bacterial
Main bacteria in neonatal bacterial meningitis?
Listeria monocytogenes
Group B Streptococci
E. coli
Main bacteria in bacterial meningitis of infants
H. influenza
Main bacteria in bacterial meningitis of those 10-21
Neisseria meningitidis (Meningococcal)
Streptococcus pneumoniae (Pneumococcal)
Main bacteria in bacterial meningitis of those 21-65
Streptococcus pneumoniae
Neisseria meningitidis
Main bacteria in bacterial meningitis in those over 65
Streptococcus pneumoniae
Listeria monocytogenes
Main bacteria in bacterial meningitis in immunosuppressed patients
Listeria monocytogenes
Main bacteria in bacterial meningitis in those who have undergone neurosurgery or head trauma
Staphylococcus
Gram negative bacilli (Klebsiella pneumoniae, E.coli, Pseudomonas aeruginosa)
Main bacteria in bacterial meningitis in those who have had a fracture of the cribriform plate?
Streptococcus pneumoniae
What is the most common form of meningitis?
Viral meningitis
What are the most common viruses in meningitis?
Enteroviruses (echovirus, Coxsackievirus)
Mumps
HSV
Herpes zoster virus
HIV
Measles
Influenza
Arboviruses
What is meant by aseptic meningitis?
Meningitis in which the CSF contains cells but no bacteria
What are some causes of aseptic meningitis?
Viral infection
Fungal infection
Parasitic infection
Atypical TB
Lyme disease
Kawasaki disease
How does meningitis occur
Microorganisms reach the meninges either by direct extension from the ears, nasopharynx, cranial injury or congenital meningeal defect, or by bloodstream spread
Describe the pathology of acute bacterial meningitis
- The pia-arachnoid is congested with polymorphs
- A layer of pus forms
- This may organize to form adhesions, causing cranial nerve palsies and hydrocephalus
- Cerebral oedema occurs in any bacterial meningitis
Give the characteristics of meningococcal meningitis (Neusseria meningitidis)
- Found in the throats of healthy carriers
- Symptoms are caused by endotoxins
- Occurs mostly in young children
- Can cause local disease or septicaemia
- 12 capsular groups of meningococcus
Give the characteristics of H.influenza meningitis?
- Part of the normal throat microbiota
- Requires blood factor for growth
- 6 sub-types (b is most common and is vaccinated against)
Give the characteristics of pneumococcal meningitis (Streptococcus pneumonia)
- Commonly found in the nasopharynx
- Most common in hospitalised patients, CSF fractures, diabetics, alcoholics and children
- Rare but high mortality