CNS Infections Flashcards
What may untreated infection cause?
- Brain herniation and death
* Cord compression and necrosis, with subsequent permanent paralysis
What is meant by the term ‘aseptic’? What may it be?
The bacterial cultures are negative
May be virus
What is acute encephalitis an infection of?
Brain parenchymal
What does pyogenic meningitis show?
A thick layer of suppurative exudate, covering the leptomeninges over the surface of the brain
i.e this is bacterial meningitis
Basically, pus in the subarachnoid space
Leptomeninges - only the arachnoid and pia
Where is exudate found in pyogenic meningitis?
In the basal and convexity surface
Microscopically, what is seen in pyogenic meningitis?
Neutrophils in the subarachnoid space
Is viral meningitis common?
YES
At what time of year does viral meningitis become an issue?
Late summer - Autumn
Suggest causes of viral meningitis.
ENTEROVIRUSES like ECHO virus
(will have bit of a flu, photophobia)
But also other microbes and non-infectious causes
How is the diagnosis of viral meningitis made?
- Viral stool culture
- Throat swab
- CSF PCR
What is the treatment of viral meningitis?
Supportive
usually self limiting
What investigation should be done in suspected encephalitis?
MRI
What questions particularly helps differentiate between meningitis and encephalitis? Explain
Is there any altered behaviour or cognition, personality change or altered consciousness?
** Encephalitis tends to present more with changes in behaviour, compared to meningitis.
What are the clinical features of encephalitis?
- Insidious onset, although sometimes sudden.
- Meningismus (a triad of headache, photophobia and nuchal rigidity)
- Stupor, coma.
- Seizures, partial paralysis.
- Confusion, psychosis.
- Speech, memory symptoms
What is meningismus?
A triad of headache, photophobia and nuchal rigidity (back of neck stiffness)
What investigations should always be carried out?
- Lumbar puncture
- EEG
- MRI
What should be done if Ix’s are delayed?
Start pre-emptive acyclovir as prompt therapy improves outcomes (death)
List the most common signs + symptoms of meningitis.
Fever + Cold Vomiting Drowsiness Muscle pain Headache Photophobia Confusion Stiff neck Rash Convulsions/seizures
What organism usually causes CAM in neonates?
Listeria
Group B strep
E. coli
What organism usually causes CAM in children?
H. influenza
What organism usually causes CAM in ages 10-21?
Neisseria meningitidis (freshers)
think ‘N’ for notty lol
What organism usually causes CAM aged over 21?
Streptococcus pneumoniae > Neisseria meningitidis
What organism usually causes CAM in those over 65?
Streptococcus pneumoniae > Listeria
What bacteria is decreased cell mediated immunity most often associated with
Listeria monocytogenes
What bacteria is neurosurgery/head trauma most often associated with?
Staphylococcus, Gram negative bacilli
What bacteria is fracture of the cribriform plate associated with?
Streptococcus pneumoniae
think in nose travels to brain through # in cribriform plate
What is the ‘alcohol triad’?
Strep pneumoniae endocarditis, bacterial pneumonia, meningitis
(think pneumonia if lying on ground drunk)
Where are clusters found?
At the base of the brain
What nerves are especially vulnerable when there is an infection?
CN’s III and VI
What prevents meningitis becoming an abscess?
Pia
What can brain abscesses cause?
Secondary ventriculitis, and hence meningitis
Name 3 sources/ways that bacterial meningitis can develop.
- Nasopharyngeal colonization
- Direct extension of bacteria -parameningeal foci (sinusitis, mastoiditis, brain abscess) OR across skull defects/fracture
- From remote foci of infection (ie. endocarditis, pneumonia, UTI)
Listeria monocytogenase likes?
FRIDGES
TB meningitis is
‘slow and grumbling’
What does neisseria meningitis cause?
Meningococcal meningitis
Where is neisseria meningitis found?
In the throats of healthy carriers
think reason why vaccination is given just before uni
How does bacteria gain access to the meninges?
Via the blood
Where may bacteria be found?
In leukocytes in the CSF
What are the symptoms of meningitis due to?
ENDOTOXIN
H. influenza is part of the normal what?
Throat microbiota
What does H. influenza require for growth?
Blood
What is the most common cause of meningitis in children under 4?
H. influenza type B
Where is S. pneumonia commonly found?
Nasopharynx
Who is most susceptible to S. pneumonia meningitis?
Hospital pts.
Pts with CSF skull fractures.
Diabetics/alcoholics.
Young children
Describe listeria monocytogenes?
gram +ve bacilli
Who is most susceptible to listeria monocytogenes?
Neonates.
>55y/o’s.
Immunosuppressed patients, especially in the context of malignancy
What is the best antibiotics for mistrial monocytogenes?
IV Ampicillin/Amoxicillin
What does someone with TB meningitis have?
TB on CXR
The CSF yield in TB meningitis is weak. What should therefore be done?
PCR and culture are important here due to the poor yield from CSF
How is TB meningitis treated?
Isoniazid + Rifampicin (add pyrazinamide + ethambutol
What type of infection is Cryptococcal Meningitis?
FUNGAL
What people get cryptococcal meningitis?
People with HIV
What kind of infection is cryptococcal meningitis?
Disseminated
How does cryptococcal meningitis appear on CSF?
Aseptic
How is cryptococcal meningitis treated?
With IV amphotericin B/flucytosine.
Fluconazole
What bloods should be done in someone with suspected meningitis?
- FBC
- Urea, creatinine, electrolytes
- LFT’s
- Clotting screen
- Procalcitonin
- PCR
- Serology
- Glucose
What are the clinical signs of bacterial meningitis?
Fever
Stiff neck
Altered level of consciousness
List signs + symptoms of bacterial meningitis.
- Headache
- Vomiting
- Pyrexia
- Neck stiffness
- Photophobia
- Lethargy
- Confusion
- Rash
When should you be cautious about doing a lumbar puncture?
If raised ICP
What position should be utilised while doing a lumbar puncture?
Sitting
If flow of CSF in a lumbar puncture is fast, what should you measure?
Opening pressure
Describe H. influenza.
Gram -ve rods
Describe S pneumonia.
Gram +ve diplococci
Describe N. meningiditis.
Gram -ve diplococci
In partially treated bacterial meningitis, what may predominate? What, however, allows this to be differentiated from viral meningitis?
Lymphocytes may predominate.
- but the protein is often high
Neutrophilic Pleocytosis + Low CSF Glucose can sometimes mean?
Bacterial meningitis
What is aseptic meningitis?
Non-pyogenic bacterial meningitis
Describe the spinal fluid in aseptic meningitis?
- A low number of WBC.
- A minimally elevated protein.
- A normal glucose
What are the indications for hospital admission?
- Signs of meningeal irritation.
- An impaired conscious level.
- A petechial rash.
- Pt is febrile or unwell, and has had a recent fit.
- Any illness, especially headache, and are close contacts of patients with meningococcal infection, even if they have received a prophylactic antibiotic
What type of swab should be taken in someone with suspected meningitis?
Throat
What should be done to petechial or purpuric skin rashes?
Disrupt and swab or aspirate
Who should get a CT before doing a lumbar puncture?
- Immunocompromised
- History of CNS disease
- New onset seizure
- Papilloedema
- Focal neurological deficit
- Altered level of consciousness
What are the key WARNING SIGNS to look for in someone with bacterial meningitis?
- Marked depressive conscious level (GCS <12) or a fluctuating conscious level (fall in GCS >2).
- Focal neurology.
- Seizure before or at presentation.
- Shock.
- Bradycardia and hypertension.
- Papilloedema
What are the indications for lumbar puncture in early inpatient management? What should be done before LP?
All adult patients with suspected meningitis, except when a clear contraindication exists
(III) or of there is a confident clinical diagnosis of meningococcal infection with a typical meningococcal rash (III)
Outline the standard management of a patient with bacterial meningitis. State what is done in penicillin allergy.
IV Ceftriaxone 2g bd.
- ADD IV Ampicillin/Amoxicillin 2g qds IF LISTERIA IS SUSPECTED.
What is given in penicillin allergy (rash or anaphylaxis)?
Chloramphenicol IV (25mg/kg 6-hourly) with Vancomycin IV (500mg 6-houtly or 1g 12-hourly) if clear hx of anaphylaxis to beta-lactams.
Co-trimoxazole alone if Listeria suspected and allergic to penicillin.
Who should steroids be given to?
ALL patients with suspected bacterial meningitis
When should steroids be given?
10mg iv 15-20 min before or with the first dose of antibiotic and then every 6 hours for 4d
When should steroids NEVER be given?
Post-surgical meningitis.
Severe immunocompromise.
Meningococcal or septic shock.
Steroid hypersensitivity
Outline option 1 of prophylaxis regimens.
Adults + Children >12yrs: Rifampicin (600mg, 12-hourly for 4 doses).
Ages 3-11: Rifampicin (10mg/kg orally, 12 hourly for 4 doses).
JUST REMEMBER RIFAMPICIN
When Rifampicin is given, what should the patient be warned of?
- Reduced efficacy of oral contraceptives.
- Red colouration of urine.
- Staining of contact lenses
Outline option 2 of prophylaxis regimens.
Adults + Children >12yrs: Ciprofloxacin (500mg orally as single dose).
- use of ciprofloxacin in younger children is NOT recommended
Outline option 3 of prophylaxis regimens.
Adults: Ceftriaxone (250mg IM as single dose).
Children <12y/o: Ceftriaxone (125mg IV as single dose).
CEFTRIAXONE
Outline option 4 of prophylaxis regimens.
Vaccines
What should be noted when taking an LP from someone with meningitis?
- Cell count
- Glucose
- Protein
- RBC’s
What cell type would be high in an LP from a patient with viral meningitis?
Neutrophils (polymorphs)
What cell type would be high in an LP from a patient with bacterial meningitis?
Lymphocytes
What are examples of what you should look for when trying to figure out the route by which someone has got viral meningitis?
Ear infection
Sinusitis
Laceration to face/head
What symptoms should ALERT you that someone has meningitis
- Crescendo headaches
- Nausea
- Fever
- Slowness
What is Kernig sign? What should you worry about?
Neck Stiffness
- Meningitis
When is imaging mandate in meningitis?
If focal neurological signs or papilloedema