CNS Infections Flashcards by Joanne McEwan

important microbes to know about?

pneumococci

meningococci

How well did you know this?

Not at all

Perfectly

untreated CNS infection has what risks?

brain herniation and death

cord compression and necrosis and subsequent permanent paralysis

How well did you know this?

Not at all

Perfectly

classification of meningitis?

acute pyogenic (bacterial)
acute aseptic (e.g viral) meningitis
acute focal suppurative infection (abscess, subdural and extradural empyema)
chronic bacterial infection (tuberculosis)
acute encephalitis (infection in brain parenchyma)

How well did you know this?

Not at all

Perfectly

aseptic meningitis?

no bacteria involved but same symptoms as meningitis

can be viral

How well did you know this?

Not at all

Perfectly

pyogenic meningitis shows what?

“pus forming”
shows thick layer of suppurative exudate over leptomeninges on surface of brain
exudate in basal and convexity surface

How well did you know this?

Not at all

Perfectly

microscopic features of pyogenic meningitis?

lots of neutrophils in subarachnoid space

How well did you know this?

Not at all

Perfectly

general rule for meningitis antibiotics?

always very high doses IV (never oral)
ceftriaxone 2g IV (or chloramphenicol if penicillin allergic)
- add vancomycin in places where it is known there are resistant meningococcus

How well did you know this?

Not at all

Perfectly

when does viral meningitis usually occur during the year?

late summer/autumn

How well did you know this?

Not at all

Perfectly

what causes viral meningitis?

enteroviruses (e.g ECHO virus)

other microbes and other non-infectious causes as well

How well did you know this?

Not at all

Perfectly

how is viral meningitis diagnosed?

viral stool culture
throat swab
CSF PCR

How well did you know this?

Not at all

Perfectly

how is viral meningitis managed?

supportive (self limiting)

How well did you know this?

Not at all

Perfectly

encephalitis features?

cerebral cortex is diffusely involved
mental status change
confusion
obtundation, stupor or coma
behavioural, memory and speech disturbance
focal or diffuse
insidious onset
meningismus (neck stiffness)
seizures, partial paralysis

How well did you know this?

Not at all

Perfectly

important differential for encephalitis?

herpes simplex virus

How well did you know this?

Not at all

Perfectly

look at flow charts for meningitis management

…

How well did you know this?

Not at all

Perfectly

encephalitis findings on MRI?

shows as diffuse white areas

- HSV encephalitis usually in temporal lobe

How well did you know this?

Not at all

Perfectly

main features of bacterial meningitis?

fever
rash
photophobia
change in mental state
nausea and vomiting

How well did you know this?

Not at all

Perfectly

main causes of bacterial meningitis depending on age?

neonates = listeria group B strep, E.coli
children = H influenzae
10-21 = Neisseria meningitidis
21+ = strep pneumoniae > Neisseria meningitidis
65+ = strep pneumoniae

How well did you know this?

Not at all

Perfectly

risk factors for bacterial meningitis?

immunocompromised
basilar skull fracture or fracture or cribiform plate
head trauma or post neurosurgery
CSF shunt

How well did you know this?

Not at all

Perfectly

impact of meningitis after infection/

can cause death

25% of people have life changing after-affects (limb loss, blindness, paralysis, cerebral palsy etc)

complications?

purulence (pus collects at base of brain and around nerves and in sulci)
invasion
cerebral oedema
ventriculitis/hydrocephalus

3 main routes of infection in bacterial meningitis?

nasopharyngeal colonization
direct extension of bacteria (brain abscess, across skull fracture etc)
from remote foci of infection (endocarditis, pneumonia etc)

principles of lumbar puncture?

only perform in clinically feasible
be cautious if increased ICP possible
use sitting position if needed
measure opening pressure if fast flow
be careful in delirium
treat with antibiotics first
CSF pleocytosis not bacterial meningitis

what tests are performed on lumbar puncture sample?

haematology (cell count etc)
microbiology (gram stain, culture)
chemistry (glucose, protein)

microbiological diagnosis of meningitis?

microscopy
biochemistry
culture
antigen detection
PCR

bacterial meningitis can be culture negative, true or false?

true | 10-15% are negative due to pre-lumbar puncture antibiotics

acute bacterial meningitis findings?

``` +ve gram stain +ve antigen detection high protein low glucose raised WBC and neutrophils ```

features of Neisseria meningitidis (meningococcal meningitis)?

``` found in throat gains access to meninges via blood stream may be found in leukocytes in CSF symptoms arise due to endotoxin most common in young kids ```

describe haemophilus influenzae meningitis?

part of normal throat microbiota requires blood factors for growth type B = most common cause of meningitis in kids <4 has a vaccine

strep pneumoniae meningitis?

found in nasopharynx common in hospitalized, skull fractures, diabetics/alcoholics and young children can be 2ndary to pneumococcal pneumonia in some cases

common causes of meningitis in immunocompromised?

listeria monocytogenes mycobacterium tuberculosis nocardia asteroids Cryptococcus neoformans (HIV with CD4<100)

listeria is resistant to what antibiotic? how is it managed instead?

ceftriaxone | management = IV ampicillin/amoxicillin

describe listeria monocytogenes?

gram +ve bacillus sporadic but becoming more common neonatal, over 55s or immunosuppressed

describe tuberous meningitis?

``` often due to reactivation in the elderly non-specific ill health previous TB on CXR poor yield from CSF high morbidity if untreated ```

how is tuberous meningitis managed?

Isoniazid + rifampicin key | add pyrazinamide + ethambutol

cryptococcal meningitis features and management?

fungal mainly in HIV CD4 < 100 subtle presentation and aseptic CSF picture management = IV amphotericin B/flucytosine, fluconazole

what is aseptic meningitis?

``` term used to describe non-pyogenic meningitis spinal fluid formula typically has - low WBC - minimally elevated protein - normal glucose ```

infectious causes of aseptic meningitis/encephalitis syndrome?

``` HSV 1 and 2 syphilis listeria tuberculosis Cryptococcus ```

non-infectious causes of aseptic meningitis?

``` carcinomatous sarcoidosis vasculitis dural venous sinus thrombosis migraine drugs ```

contact prophylaxis regimes to prevent meningitis if you've come into contact with someone?

600mg rifampicin orally every 12 hours for 4 doses (age 12+) 10mg/kg rifampicin every 12 hrs for 4 doses (3-11 months) or 500mg ciprofloxacin orally as single dose or 250mg ceftriaxone intramuscularly as single dose

how are secondary cases of meningitis prevented?

phone public health | keep GP records of all close contact to people with meningitis

indications for hospital admission?

``` signs of meningeal irritation impaired conscious level petechial rash febrile/unwell and has a recent fit illness after contact with someone with meningitis ```

what action should be taken on admission to hospital?

blood cultures give treatment take a throat swab disrupt and swab or aspirate any petechial or purpuric skin lesions for microscopy and culture

who should receive a lumbar puncture?

all adult patients with suspected meningitis except when there is a clear contraindication or if there is a clear clinical diagnosis

are antibiotics given before or after lumbar puncture?

before

empirical antibiotic therapy?

2g IV ceftriaxone bd - add IV ampicillin/amoxicillin 2g if listeria suspected - penicillin allergy = chloramphenicol IV + vancomycin IV - listeria + penicillin allergy = co-trimoxazole

how are steroids used in meningitis?

give to all patients with suspected bacterial meningitis before or with first dose of antibiotics - don't give in post-surgical, immunocompromised or septic shock

which causes of meningitis have vaccines?

Neisseria meningitidis (YWCA) haemophilus influenzae strep pneumoniae