CNS infections Flashcards
What is the difference between meningitis and encephalitis?
meningitis - infection of the meninges
encephalitis - infection of the brain itself
Bacterial meningitis - what is it also known as
Pyogenic meningitis
Bacterial meningitis - where is the inflammation
Inflammation of the leptomeninges and CSF within the subarachnoid space
Bacterial meningitis. Thick layer of suppurative exudate covers the surface of the brain. True or false?
True
- think of injecting pus into the CSF and the pus gets everywhere and gets matted
Bacterial meningitis - patient with CNS devices (e.g. cochlear implants) - what is the likely causative organism?
Strep pneumoniae (pneumococcal meningitis)
Where is strep pneumoniae commonly found?
Nasopharynx
Bacterial meningitis - patient with CSF skull fracture - what is the likely causative organism?
Strep pneumoniae
Bacterial meningitis - what is the likely causative organism in adolescents?
Neisseria meningitidies (meningococcal meningitis)
Neisseria meningitides is intracellular/extracellular?
Intracellular
Neisseria meningitides likely gains access to the meninges through _______
The bloodstream
Bacterial meningitis - in the past what was the likely causative organism in childhood but incidence has decreased now due to introduction of vaccine?
Haemophilus influenzae
Bacterial meningitis - extremes of age (over 60 and neonates) - what is the likely causative organism?
Listeria monocytogenes
Bacterial meningitis - immunocompromised patients - what is the likely causative organism?
Listeria monocytogenes
Bacterial meningitis - E coli affects
Neonates
Bacterial meningitis - H influenzae affects
Infants and children
Bacterial meningitis - neisseria meningitides affects
Young adults
Bacterial meningitis - listeria monocytogenes affects
Elderly
and neonates
Bacterial meningitis - strep pneumoniae affects
Over 21 year olds (roughly)
Bacterial meningitis - from head trauma/neurosurgery - what is the likely causative organism (2)
Staph aureus
Staph epidermidis
Bacterial meningitis - microscopically, there will be an abundance of _____ in the subarachnoid space?
Polymorphs (neutrophils)
Bacterial meningitis - clinical features
Crescendo headache Fever Change in mental state Neck stiffness N+V Photophobia Confusion Slowness in responding to questions Non blanching ash
Bacterial meningitis - what are the 5 warning features
Marked decline in conscious level Focal neurology Seizure before or at presentation Bradycardia + hypertension Papilloedema
Bacterial meningitis - investigations
Bloods
Throat swab
CSF lumbar puncture
What is the best way to determine aetiology (viral vs bacterial) meningitis?
CSF lumbar puncture
Bacterial meningitis - CSF lumbar puncture findings
Increased neutrophils (abundant polymorphs)
Low CSF glucose
Bacterial meningitis - antibiotics should not be given until CSF lumbar puncture has been carried out. True or false?
False
- antibiotics should be given before lumbar puncture
Bacterial meningitis - which patients should undergo CT prior to lumbar puncture?
Immunocompromised patients Pts with Hx of CNS disease Papilloedema Focal neurological deficit New onset seizure
Management of suspected bacterial meningitis
High doses of antibiotics because you need to get into the CNS which is matted with pus
Bacterial meningitis - which antibiotics are used?
Ceftriaxone IV 2g bd
Cefotaxime 2g qds
Bacterial meningitis - which antibiotics are used if penicilin allergic ?
Chloraphenicol IV 25mg/kg qds
+ Vancomycin
Bacterial meningitis - aside from antibiotics, what is also administered to the patient
Dexamethasone IV 10mg qds
Bacterial meningitis - when is dexamethasone given in relation to antibiotics?
This is started with or just before first dose of antibiotics
Bacterial meningitis - why is dexamethasone administered?
Required if the causative organism is strep pneumonia.
If the causative organism is strep pneumoniae, dexamethasone should be continues for 4 days
If the causative organism is not strep pneumoniae, dexamethasone should be stopped
Bacterial meningitis management - if patient is over 60 which additional antibiotic should be administered
2mg amoxicillin
Why is amoxicillin given in over 60 year olds?
As the likely organism may be listeria
Bacterial meningitis - when organism is confirmed to be listeria, what is the management?
Ceftriaxone +
Dexamethasone +
Amoxicillin
Bacterial meningitis - if the patient has recently travelled to a country with high rates of penicillin resistant pneumococci then what should be added to management?
Rifampicin
If a patient has suspected meningitis, public health must be informed. True or false?
True
What are the prophylactic regimes if you have been in contact with a patient with meningitis?
600mg rifampicin
Bacterial meningitis - complications
Cerebral oedema
Hydrocephalus
Bacterial meningitis - vaccinations
Haemophilus influenzae B
Neisseria meningitides
Pneumococcal vaccines
Aseptic meningitis - definition
In patients where there is no bacteria found on investigation but you think there is some form of meningococcal infection
Aseptic meningitis - CSF results
Low number of WBC
Normal glucose
No bacteria
Aseptic meningitis - causes
Viruses (most common)
Fungi
Spirochetes
Viral meningitis - cause
Enterovirus (ECHO virus)
Travel related viruses
Viral meningitis - investigations
Viral stool culture
Throat swab
CSF PCR
Lumbar puncture
Viral meningitis - lumbar puncture findings
Lots of lymphocytes
Viral meningitis - management
Self limiting
Encephalitis - causative organism
Herpes simplex virus (HSV)
Encephalitis has a sudden onset. True or false?
False
- gradual onset
Encephalitis - clinical features
Mental state change Seizures Partial paralysis Confusion Speech problems Behavioural disturbances Meningismus - stiffness in the head
Encephalitis - always do a lumbar puncture. True or false?
False
- try to do a lumbar puncture but if unsafe then do a CT scan
Encephalitis - most useful investigation
MRI scan
Encephalitis - management
IV aciclovir
Which antibiotic is first line for most cases of meningitis? IV vancomycin IV amoxicillin IV ceftriaxone IV chloramphenicol IV co-trimoxazole
IV ceftriaxone