CNS infections Flashcards
What happens grossly with pyogenic meningitis?
a thick layer of suppurative exudate which covers the meninges over the surfave of the brain esp. in basal and convex surfaces
What is seen micrsocopically in pyogenic meningitis?
neutrophils in the subarachnoid space
When is viral meningitis commonly seen?
late summer/autumn
What commonly causes viral meningitis?
enteroviruses eg ECHO
What investigations are done with viral meningitis?
viral stool culture; throat swab and CSF PCR
What is the treatment for viral meningitis?
supportive as self-limiting
What are the clinical features of encephalitis?
insidious onset; sometimes sudden; meningismus; stupor, coma; seizures; confusion; psychosis; speech and memory symptoms
What are the investigations for encephalitis?
LP; EEG and MRI
What treatment should be started immediately with encephalitiy?
aciclovir
What are the most common causes of bacterial meningitis in neonates?
listeria; group B strep; e.coli
What are the most common causes of bacterial meningitis in children?
H.influenza
What are the most common causes of bacterial meningitis in ages 10-21?
neisseria meningitidis
What are the most common causes of bacterial meningitis over 21s?
strep. pneumo > neisseria meningitidis
What are the most common causes of bacterial meningitis in over 65s?
strep. pneumo > listeria
What bugs do patients wti hdecreased cell mediated immunity tend to get?
listeria monocytogenes
What bugs do neurosurgery or head trauma pts get?
staph; gram negatvie bacilli; s.epidermidis
What bug do patients with cribiform plate #s get?
strep. pnuemo
What bugs do patients with a CSF shunt get?
s. epidermidis; s.aureus; aerobic GNR; propionibacterium acnes
What CNs are particularly vulnerable in purulent meningitis?
III and VI
What prevents meningitis becoming an abscess?
pia
What antibiotic is given for listeria?
amoxicillin
How does meningitis cause hydrocephalus?
flow of CSF blocked due to puss
What are the routes of pathogenesis of bacterial meningitis?
nasopharyngeal colonisation; direct extension of bacteria; from remote foci of infection
What causes symptoms of with neisseria meningitis?
endotoxin
Who is most susceptible to s.pneumoniae meningitis?
hospitalised pts; patients with CSF skull #s; dibaetics/alcoholic and young children
What CNS device is associated with S.pneumoniae?
cochlear implants
What type of bacteria is listerai monocytogenes?
gram positive bacilli
Who gets TB meningitis?
elderly
Who gets cryptococcal meningitis?
HIV CD4<100
What is the treatment for cryptococcal meningitis?
IV amphotericin
What is given empirically for suspected meningitis?
cefotaxime or ceftriaxone and dexamethosone
What are the signs of bacterial meningitis?
fever; stiff neck and alteration in conscousness; heache; vomiting; photophobia; rash
What is seen typically on LP with bacterial meningitis?
neutrophilic pleocytosis and low CSF glucose
What are causes of non-infectious meningitis?
chemical meningitis-contrast; behcet syndrome and drug-induced
What is aseptic meningitis?
meningitis that has has low number of WBC; minimally elevated protein and a normal glucose on LP
Who should have a CT before an LP?
immunocompromised; hx of CNS disease; new onset seizures; papilloedema; altered consciousness; focal neurologic deficits
What are warning signs with meningitis?
makred depressive conscious level; focal neurology; seizures; shock; bradycardia and HT; papilloedema
What is given for penicillin allergy empirically?
chloramphenicol with vancomycin
What is given penicillin allergy for listeria?
co-trimaxazole
What is given prophylactically for those been in contact with meningitis patient?
ciprofloxacin
How many groups of meningococcus are ther?
12
What capsular groups of meningococcus are more common in the UK?
B,C, W and Y
When is listeria cover required?
> 60 years; immunocompromised (inc DM and alcohol)
What bug should be considered in a pt with encephalitis and contact with fresh water?
leptospirosis
Give an example of an aerobic GNR?
Pseudomonas
What is given for penicillin resistant pneumococci?
vancomycin or rifampicin
what drugs can cause aseptic meningitis?
co-trimoxazole; IVIG; NSAIDs
What indicates a fluctuating conscious level?
> 2 fall in GCS
