CNS Infections Flashcards
What is acute encephalitis?
infection and inflammation of the brain parenchyma
what conditions are covered by the term focal suppurative infection?
abscess
subdural empyema
extradural empyema
What viruses typically cause viral meningitis?
enterovirus - ECHO
How is viral meningitis diagnosed?
viral stool culture
throat swab
CSF PCR
How is viral meningitis treated?
supportive treatment - self-limiting
What virus typically cause viral encephalitis?
HSV1 Varicella zoster CMV HIV Measles
What is important about HSV encephalitis treatment?
rapid treatment within 6 hours
What is used to treat HSV encephalitis?
aciclovir IV high dose
What are common travel related encephalitis’?
West nile
Japanese B
Tick borne
What are the clinical features of encephalitis?
insidious onset meningismus stupor, coma seizures/paralysis confusion, psychosis speech and memory problems
What investigations are done in encephalitis?
LP
EEG
MRI
What findings are seen on MRI in encephalitis?
inflamed temporal lobe involving uncut and parahippocampal gyrus (WHITE ON MRI)
What are common causative organisms of bacterial meningitis in neonates?
listeria
group B strep
E coli
What are common causative organisms of bacterial meningitis in children?
Hib
What are common causative organisms of bacterial meningitis in 10-21yo?
meningococcal
What are common causative organisms of bacterial meningitis in 21 onwards?
pneumococcal > meningococcal
What are common causative organisms of bacterial meningitis in elderly patients?
pneumococcal > listeria
Which bacteria is likely to cause a meningitis with a history of cribriform plate fracture?
pneumococcal
Which bacteria is likely to cause a meningitis with a history of neurosurgery or open head trauma?
staph aureus/epidermidis
gram negative rods
Which bacteria is likely to cause a meningitis with a history of immunocompromisation?
s. pneumoniae
n. meningitidis
listeria
pseudomonas
Which bacteria is likely to cause a meningitis with a history of CSF shunt?
staph epidermidis
staph aureus
aerobic GNR
propionibacterium acnes
What are the pathogeneses behind bacterial meningitis?
nasopharyngeal colonisation leading to direct extension of bacteria from sinusitis, mastoiditis or abscess.
from remote foci - endocarditis, pneumonia, UTI
What percentage of pre-school children carry pneumococcus?
60%
What causes symptoms in N. meningitidis meningitis?
endotoxin
How are people vaccinated against N. meningitis?
purified capsular polysaccharide
Where is H. influenza normally found?
normal throat microbiota
Is there a vaccine available against HiB?
yes - conjugated vaccine against capsular polysaccharide is available
Where is strep pneumoniae normally found?
nasopharynx
What is significant about strep pneumoniae infection?
rare and has a high mortality rate
What is listeria monocytogenes?
gram positive bacilli
What antibiotic is used against listeria?
IV ampicillin/amoxicillin
Why is ceftriaxone not used in listeria?
bacteria are intrinsically resistant
What population is TB meningitis seen in?
elderly - reactivation
foreign travel
how is TB meningitis treated?
isoniazid + rifampicin
What kind of organism causes cryptococcal meningitis?
fungus
What disease is cryptococcal meningitis seen in?
HIV - CD4<100
What is the treatment for cryptococcal meningitis?
IV Amphotericin B/flucytosine
fluconazole
Where can the cryptococcal antigen be found in patients suffering cryptococcal meningitis?
serum and CSF
What are the differential diagnoses of meningitis?
meningitis encephalitis cerebral abscess severe sepsis from other source SAH cerebral tumour
What can happen if ABX are given before LP?
gram stains of CSF may be negative
What type of white cells are high in viral meningitis?
lymphocytes
What type of white cells are high in bacterial meningitis?
neutrophils
What type of white cells are seen in TB meningitis?
lymphocytes
Which type of meningitis typically exhibits a very high protein count?
TB meningitis
Which types of meningitis cause a reduction in CSF glucose?
bacterial
TB
What is aseptic meningitis?
non-pyogenic bacterial meningitis
What CSF make up is typically seen in aseptic meningitis?
low WBC
minimally elevated protein
normal glucose
You should always wait until culture results come back before beginning any antibiotic treatment - T/F?
False - never delay Abx
What are the indications for a CT scan in meningitis patients?
focal neurology
papilloedema
What are the main serious warning signs in a patient with meningitis?
decreased consciousness level focal neurology seizure at or before presentation shock bradycardia hypertension papilloedema
What is the correct empirical antibiotic therapy for a patient with meningitis?
IV Ceftriaxone 2g BD
add ampicillin/amoxicilin 2mg qds if listeria suspected
What treatment should be given in patients allergic to penicillin?
chloramphenicol 25mg/kg 6 hourly + vancomycin 500mg 6 hourly
What medication should be given to all patients suspected of bacterial meningitis before or with the first dose of antibiotics and then 6 hourly for 4 days?
steroids - dex
When should steroids not be given?
post-op meningitis
septic shock
steroid hypersensitivity
What antibiotic is used in contact prophylaxis of meningitis in adults and children over 12 years old?
rifampicin 600mg orally every 12 hours
what are common side-effects of rifampicin?
red colouration of bodily fluids
reduced OCP efficacy
