CNS Infections Flashcards
Why are CNS infections so important to diagnose quickly?
Untreated can cause brain herniation and death or permanent paralysis, as brain and spinal cord do not regenerate
Describe pyogenic meningitis morphologically
Thick layer of suppurative exudate covering the leptomeninges over the surface of the brain
Describe pyogenic meningitis microscopically
Neutrophils in the subarachnoid space
Which types of viruses cause viral meningitis?
Enteroviruses
How is viral meningitis diagnosed?
Viral stool culture
Throat swab
CSF PCR
Examples of viruses that cause viral encephalitis and treatment
Herpes simplex- Rapid high dose aciclovir
Varicella zoster- high dose aciclovir
CMV, HIV, Measles, West Nile, Rabies
Clinical features of encephalitis
Meningismus Stupor/coma Seizures, paralysis Confusion, psychosis Speech and memory symptoms
Examples of meningitis complications
Limb loss Deafness Blindness Cerebral palsy Quadriplegia Mental impairment
Pathogenesis of bacterial meningitis
1) Nasopharyngeal colonisation
2) Direct extension of bacteria eg from sinusitis, Mastoiditis or brain abcess across skull defect or fracture
3) From remote foci of infection eg endocarditis, pneumonia, UTI
What bacteria causes meningococcal meningitis, how does it gain access to the meninges, and what causes the symptoms it causes?
Neisseria meningitis
Accesses meninges through blood stream
Symptoms due to endotoxin
Which patients are most susceptible to Strep pneumoniae meningitis
Hospital, CSF skull fractures, diabetics and alocholics, young children
Which patients are most susceptible to listeria monocytogenes and what is the treatment of choice
Neonates, >55 years, Immuno suppressed
IV ampicillin/amoxicillin
Which patients are most susceptible to cryptococcal meningitis (also what kind of infection is it+treatment)
HIV patients
Fungal infection
IV amphotericin B/Flucytosine + Fluconazole
Clinical signs of bacterial meningitis
Fever
Neck stiffness
Altered conciousness
How can meningitis be diagnosed from a microbiology POV
Blood culture
Throat swab
Blood EDTA for PCR
CSF fluid (Lumbar Puncture)
What is aseptic meningitis?
A term used to mean non pyogenic meningitis
CSF has low WBC, normal glucose, slightly elevated protein
When is a CT scan indicated?
When patients have papilloedema or focal neurological signs
ABx should not be delayed for investigations
Empiric ABx therapy
IV Ceftriaxone 2g bd
+ IV ampicillin/ amoxicillin 2g qds if listeria suspected
Penicillin allergy
Chloramphenicol with vancomycin
Co-trimoxazole has been used succesfully on own.
What role do steroids play?
All patients with suspected bac meningitis should get before or with first dose of ABx, reduces mortality
Don’t give in immunocmpromised
