What are consequences of untreated CNS infections?
Brain herniation (Monro Kellie)
Cord compression and necrosis
What is the difference between meningitis and encephalitis?
Meningitis - meninges affected only
Encephalitis - diffuse infection of brain tissue
What is the difference between encephalitis and encephalopathy?
Encephalopathy - broader term meaning any disease of the brain
What does aseptic meningitis mean?
No bacteria isolated from culture after two days
Could mean inflammation has viral/other origin
Chronic CNS infections are common in people who are ___.
What is an example?
immunosuppressed
TB
Why are brain abscesses particularly dangerous?
Focal area of pus in the brain
causing FOCAL SYMPTOMS
What is pyogenic meningitis?
Meningitis caused by purulent bacteria
What does Strep. pneumoniae look like on a Gram film?
Gram positive cocci in chains
What does Meningococcus look like on a Gram film?
Encapsulated Gram -ve cocci
What does Listeria monocytogenes look like on a Gram film?
Gram positive bacilli
What does H influenzae look like on a Gram film?
Gram negative bacillus
What is the second most common type of meningitis after bacterial?
Viral meningitis
When in the year does viral meningitis tend to present?
Late summer
How is viral meningitis investigated?
Pharyngeal swab for viral PCR
Stool sample (for enterococcus)
What are the important viruses which cause meningitis?
Enterococcus
HSV
Mumps (in countries which aren’t vaccinated for it)
How does meningitis tend to present?
Fever
Headache
Neck stiffness
+/- meningococcal rash
What is the difference between the presentations of meningitis and encephalitis?
Meningitis - classic triad of headache, fever and neck stiffness
Encephalitis - diffuse infection, so widespread mental state changes +/- sepsis
Neck stiffness tends to be a feature of (meningitis / encephalitis).
meningitis
What virus should you worry about in people presenting with encephalitis?
HSV
Which treatment is given for suspected encephalitis?
Aciclovir IV
Which imaging modality is helpful in diagnosing encephalitis?
MRI brain
Which organisms should you strongly suspect in patients with bacterial meningitis?
Neisseria meningitidis / Meningococcus - most common, accompanied by a rash
Strep. pneumoniae - next most common
Listeria monocytogenes - in those > 60, immunosuppressed
H. influenzae - in children who haven’t been vaccinated
How do most cases of bacterial meningitis start?
Colonisation of nasopharynx by meningococcus
What is the gold standard investigation for bacterial meningitis?
Lumbar puncture –> CSF culture
In bacterial meningitis, CSF white blood count is raised.
Which value is typical of bacterial meningitis?
>2000
In bacterial meningitis, CSF glucose conc. will be (more than / less than) that of blood glucose.
less than
because the bugs are munching it
Which investigation amplifies the amount of bug present and helps you to identify the causal agent of a meningitis?
PCR
Where does meningococcus colonise?
Nasopharynx
What is a cutaneous sign of meningococcal septicaemia?
Widespread, non-blanching purpuric rash
Why is H influenzae meningitis much less common nowadays?
Vaccination
Who tends to get Strep meningitis?
Kids
Hospitalised patients
Patients with cochlear implants
Who tends to get Listeria meningitis?
Older patients (>60)
Immunosuppressed
What is the antibiotic of choice for
a) meningococcal / Strep
b) Listeria
meningitis?
a) Ceftriaxone
b) Ceftriaxone + Amoxicilin (latter is the effective one, keep cef until you eliminate the others)
What are some causes of aseptic meningitis?
Viral infection
Irritation of meninges by infection elsewhere
Amoebic meningitis
Chemical-induced
Behcets syndrome
Drugs
What is the antibiotic of choice for bacterial meningitis?
Ceftriaxone
(Chloramphenicol if allergic)
What is given alongside Ceftriaxone for most cases of bacterial meningitis?
Dexamethasone
proven to help in Strep infection, if confirmed not Strep, stop it
Which antibiotic is ADDED in suspected Listeria infection?
Amoxicillin
Meningitis is a ___ disease, meaning any new cases must be reported to ___ ___.
notifiable
Public Health
What is given as prophylaxis for bacterial meningitis?
Vaccination
How do bacteria reach the meninges?
Direct spread from nasopharynx
Invasion from other sites of trauma/infection e.g sinuses, fractures
Invasion via bloodstream
What are the symptoms of meningitis?
Fever
Headache
Neck stiffness
(In meningococcal infections there may be a widespread purpuric rash)
What is Kernig’s sign?
If patient is lying supine and asked to extend knee from 90 degree flexion, they won’t be able to
Physically demonstrable sign of meningitis
As meningitis progresses, patients experience ___ symptoms like photophobia and a reduced conscious level.
neurological symptoms
What biochemical patterns will you see on lumbar puncture of someone with acute bacterial meningitis?
Raised WBC and neutrophils
Raised protein
Low CSF glucose
What biochemical patterns will you see on lumbar puncture of someone with viral meningitis?
No Gram results (not bacteria)
Normal glucose
What biochemical patterns would you see on lumbar puncture of a patient with chronic tuberculous meningitis?
Raised WBC and lymphocytes (chronic inflammation)
Raised protein
Reduced CSF glucose (because the bugs are using it)
Which antibiotic is given first line for bacterial meningitis?
Ceftriaxone IV
2g BD
Which antibiotic is given first line for suspected bacterial meningitis if a patient is allergic to beta lactams?
Chloramphenicol
What drug is given to every patient with bacterial meningitis in addition to ceftriaxone?
Why?
Dexamethasone
Proven to improve outcomes in Strep. pnuemoniae infection, if another bug cultured you would stop it
For bacterial meningitis, which drug is added to ceftriaxone + dexamethasone if a patient is > 60 or immunocompromised?
Why?
Amoxicillin
Ceftriaxone isn’t effective on Listeria
Which drug is given first line for suspected viral meningitis?
Aciclovir IV