CNS Infections Flashcards
What is meningitis?
Inflammation of the pia and arachnoid mater
What is meningism?
Stiffness of the neck, photophobia, severe headache
What are general symptoms of bacterial/viral meningitis?
Fever, feel unwell, rash
In what type of meningitis is the rash haemorrhagic?
Meningococcal meningitis
What are the main viruses that can cause meningitis?
Enteroviruses, HSV, Mumps, Lymphocytic choriomeningitis virus
What is the main bacteria that can cause meningitis in neonates?
E.coli
What are the main bacteria that can cause meningitis in infants, young adults and the elderly?
Neisseria meningitidis, Streptococcus pneumoniae
What is encephalitits?
Inflammation of the cerebral cortex
What are the symptoms of encephalitis?
Lethargy and fatigue, decreased level of consciousness, fever, occasionally there may be fits
What’s it called if a patient has encephalitis and meningism?
Meningo-encephalitis
What are the viruses that can cause encephalitis?
HSV, VZV, Paroviruses, HIV, Mumps, Measles
What does normal CSF look like?
Gin-clear with a pressure of <15 cm of H2O
What analysis can you perform on CSF?
Cell count, gram film, protein, glucose, culture on blood/chocolate agar, PCR
What blood tests can you do?
Blood cultures and PCR
What nose/throat swab tests can you do?
Blood/chocolate agar and PCR
What stool test can you do?
PCR
What CSF changes are consistent with a bacterial infection?
Neutrophil dominant leucocytosis, raised protein, reduced CSF glucose to serum glucose ratio
What pathogen is it if gram stain shows gram negative cocco-bacilli, chocolate agar grows small white colonies and growth only occurs around the X&V disc on nutrient agar?
Haemophilus influenzae
How should you treat empirically in a 9 month old with suspected meningitis?
IV cefotaxime or ceftriaxone
Why should you also give IV dexamethasone be started in some meningitis cases?
It reduces the risk of long term neurological complications from some bacterial causes of meningitis
When should IV dexamethasone be started?
As soon as diagnosis is considered
What bacteria is it if gram stain shows gram positive diplococci and blood agar shows alpha-haemolytic colonies that are sensitive to optochin?
S.pneumoniae
What drugs should you start empirically in a 1 day old baby who’s become floppy and blue?
Cefotaxime and amoxicillin
What bacteria is it if gram stain shows gram positive cocci in chains, blood agar shows beta-haemolytic colonies and latex agglutination test shows Lancefield group B?
Group B streptococcus
What is the most likely source of Group B streptococcus?
Maternal genital tract
What % of people who can child-bear may be asymptomatically carry Group B strep in their genital tract?
Up to 25%
What is the likely pathogen if the patient is immunosuppressed, gram stain shows gram positive bacilli and blood agar shows pinpoint/small semi-transparent colonies with narrow haemolytic zone?
Listeria monocytogenes
Who is at risk of meningitis from L.monocytogenes?
Anyone immunocompromised, pregnant women, neonates, older individuals, immunosuppressive conditions, chronic glucocorticosteroid use, DM
How should you manage meningitis caused by L.monocytogenes?
IV amoxicillin at a high dose and high frequency. You can also add IV gentamicin
What bacteria is it if the history is classic meningitis in a university student?
Neisseria meningitidis
How can Neisseria meningitidis be confirmed?
Peripheral blood culture/molecular testing, lumbar puncture isn’t necessary
What does N.meningitidis look like on a gram film?
Gram negative diplococci
What should you do when someone is diagnosed with meningitis?
Inform PHE and give close contacts antibiotic prophylaxis, a single dose of oral ciprofloxacin
What CSF changes indicate viral encephalitis or meningitis?
Predominantly lymphocytic response, moderately raised protein, glucose more than 50% of the level in the paired serum sample
What should you start when HSV encephalitis is probable?
IV acyclovir
What investigation should you do to confirm HSV encephalitis?
PCR
