Infections of the nervous system Flashcards
What is brain parenchyma?
Functional tissue in the brain
The involvement of what structure is hallmark of encephalitis?
In encephalitis the brain parenchyma is inflamed
What are the classifications of meningitis?
- Acute pyogenic (bacterial) meningitis
- Acute aseptic (e.g. viral, non-infectious) meningitis
- Acute focal suppurative infection (brain abscess, subdural/extradural empyema)
- Chronic bacterial infection (TB)
- Acute encephalitis (brain parenchyma)
How does pyogenic meningitis appear under a microscope?
Neutrophils in subarachnoid space
What antibiotics are given for pyogenic meningitis?
Ceftriaxone + Dexamethasone
If listeria add Amoxicillin 4 hourly
When do you give steroids in pyogenic meningitis?
10mg IV 15-20 mins before or with first dose of antibiotics and then every 6 hours for 4 days
What is a contra-indication for giving steroids to a patient with meningitis?
- post-surgical meningitis
- Meningococcal
- Septic shock
- Patients hypersensitive to steroids
What type of pyogenic meningitis benefits most from steroid treatment?
Pneumococcal meningitis
When is viral meningitis most often seen?
Late summer / autumn
What aspect of a patients history gives a big clue to viral meningitis?
Travel history
What organisms cause viral meningitis?
Enteroviruses e.g. ECHO virus
How is viral meningitis diagnosed?
Viral stool PCR + culture, throat swab & CSF PCR
What is the treatment for viral meningitis?
Supportive as the condition tends to be self limiting
What are some symptoms of encephalitis?
- Mental status change
- Confusion
- Obtundation or coma
- Seizure
- Behavioral & speech disturbance
- Focal or diffuse neurological signs
What are some symptoms of Meningo-encephalitis?
- Headache
- fever
- Neck stiffness
+
encephalitis features
Is the cerebral cortex affected by encephalitis?
Yes
Does encephalitis tend to have a insidious or sudden onset?
Most likely insidious
What investigations are done for encephalitis?
- Lumbar puncture (1st line)
- EEG
- MRI
If there’s a delay in encephalitis investigation what do you do?
Give aciclovir
What are some general symptoms of CNS infections?
- Headache
- Vomiting
- Pyrexia
- Neck stiffness
- Photophobia
- Lethargy
- Confusion
- Rash
What organisms are most likely to cause community acquired pyogenic meningitis in neonates?
Listeria
Group B strep
E.coli
What organism is most likely to cause community acquired pyogenic meningitis in children?
H. Influenza
What organisms are most likely to cause community acquired pyogenic meningitis in over 65s?
- Strep pneumoniae
- Listeria
If a patient has decreased cell mediated immunity what organism is most likely to cause community acquired pyogenic meningitis?
Listeria
If a patient has a fractured cribriform plate what organism is most likely to cause community acquired pyogenic meningitis?
Strep pneumoniae
If a patient has had neurosurgery or head trauma what organism is most likely to cause community acquired pyogenic meningitis?
- Staphylococcus
- G-ve bacili
What patients with meningitis should undergo a CT before lumbar puncture?
- Immunocompromised
- History of CNS disease
- New onset seizure
- Papillodema
- Abnormal level of consciousness
- Focal neurological deficit
CSF 99% predictive of bacterial meningitis if what readings are seen?
- WBC >200
- Neutrophils >1180
- Protein >220mg/dl
- Glucose <34mg/dl
- Glucose (CSF/serum) <0.23
What viruses commonly cause viral meningitis in immunosuppressed patients?
EBV
CMV
What viruses commonly cause meningitis in regular patients?
- Enteroviruses
- HSV 1&2
- M. tuberculosis
- Pneumococci
- Meningococci
- H. influenzae
What organism causes meningococcal meningitis?
N. Meningitidus
What group of patients is meningococcal meningitis most common in?
young kids
What is the mortality rate of localized meningitis?
5%
What is the mortality rate of meningitis with septicemia?
15%
What is the mortality rate of fulminant (severe) septicaemia?
15-40%
Which of the 12 capsular groups of meningococcus are most common in the UK?
B, C, W & Y
What medication is first line for meningitis?
Ceftriaxone (not useful for listeria infections) + dexamethasone
What is the most common cause of meningitis in children under 6 years old?
H. Influenzae type b
Who’s is most at risk of strep pneumoniae meningitis?
- Hospitalized patients
- Patients with CSF skull fractures
- Diabetics/alcoholics
- Young children
What antibiotic is given for listeria infection meningitis?
IV ampicillin/amoxicillin
What medication is given for tuberculous meningitis?
Isonazid + rifampicin
Add pyrazinamide + ethambutol
What medication is given for cryptococcal meningitis?
Fluconazole
If a patient has meningitis and is over 60 what medication do you add
Amoxicillin
If patient is pen allergic and has meningitis what do you give?
chloramphenicol + dexamethasone
If a meningitis patient is pen allergic and is over 6o what medication do you add?
co-trimoxazole
What drugs can be used for meningitis prophylaxis?
- Rifampicin
- Ciprofloxacin
- Ceftriaxone
What drug is given to close contacts of meningitis patients?
ciprofloxacin
