CNS infections* Flashcards by Aisha Mujahid

What type of meningitis shows a thick layer of suppurative exudate that covers the leptomeninges over the surface of the brain

pyogenic (bacterial)

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microscopically what does pyogenic meningitis show

neutrophils in the subarachnoid space

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when does viral meningitis occur
causes
dx
rx

late summer/autumn
enteroviruses (ECHO), other microbes and non-infectious causes also
viral stool culture, throat swab and CSF PCR
supportive as self limiting

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how to treat viral encephalitis caused by herpex simplex

high dose IV aciclovir

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how to treat viral encephalitis caused by varicella zoster and who does it occur in

history of shingles

high dose acyclovir

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what other viruses can cause viral encephalitis

CMB, HIV, measles

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what are some travel related causes of viral encephalitis

west nile, japanese B encephalitis, tick borne encephalitis

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what are some occupational related causes of encephalitis

rabies

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clinical features of encephalitis (9)

insidious onset, sometimes sudden
stupor
coma
meningismus
seizures
partial paralysis 
confusion 
psychosis 
speech &amp;memory problems

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investigations for encephalitis and what should be done if there is a delay

LP, EEG, MRI

start acicilovir pre emptive

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how do cerebral abscesses arise

spread from intracranial infection such as mastoiditis but usually via blood stream

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common causes of cerebral abscesses

congenital HD, pulmonary AV fistulas, bronchiectasis, lung abscess, bacterial endocarditis

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common organisms in cerebral abscesses and which is the commonest

strep viridian’s (commonest)

SA, haemolytic strep, enterbacteriacie, bacteroids and other anaerobes

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what are the organisms in immunosuppressed for cerebral abscesses

fungal or toxoplasmic gondii abscesses may occur

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symptoms and signs of cerebral abscess (4 and one negative)

headache
focal neurological deficits
papilloedema
nausea and vom

fever, chills and other signs of infections do not occur

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diagnosis of abscesses

contrast enhanced CT/MRI
if dx in doubt then do a stereotaxic brain biopsy which will confirm the lesion is an abscess
cultures
empiric treatment

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organisms in bacterial meningitis

neonates - listeria, group b strep, EColi
children - HI
10-21-meningococcal 
21 onwards - pneumococcal>meningococcal 
elderly - pneumococcal>listeria

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risk factors for listers, staph GNR and pneumococcal acquired bacteria meningitis

decreased CMI
neurosurgery/open head trauma
fracture of the cribriform plate

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organisms in BM in immunocomprimised state
basically skull fracture
head trauma or neurosurgery
CSF shunt

S pneumonia, N meningitis, listeria, aerobic GNR, mycobacterium tuberculosis, cryptococcus neofromans

S pneumonia, HI, beta haemolytic strep group A

SA, S epidermis, aerobic GNR

SE, SA, aerobic GNR, propionibacterium acnes

3 types pf pathogenesis of BM

nasopharyngeal colonisation
direct extension of bacteria
from remote foci of infection (endocarditis, UTI, pneumonia)

Meningococcal meningitis 
found where in healthy people?
how does it get to meninges?
where is the bacteria found?
what are the symptoms due to?
who is the disease commonly in?
vaccination in who?

throats 
bloodstream
leukocytes in CSF
endotoxin 
young children 
military recruits

HI meningitis
part of what normally?
what does it require for growth?
how many different types?

part of normal throat microbiota
required blood factors
6 types, HI b commonest in under 4s

Pneumococcal meningitis
where is it commonly found?
who is more susceptible to this?
what implants is it linked to

nasopharynx
hospitalised patients, CSF skull fractures, diabetics/alcoholics and young children
cochlear implants - rare but high mortality

Listeria monocytogenes 
gram what?
who?
antibiotic? 
what antibiotic has no value

gram positive bacilli
neonatal, >55s, immunosuppressed
IV ampicillin/amox
ceftriaxone is intrinsically resistant

``` Tuberculous meningitis who? symptoms? CSF what? rx? ```

elderly non specific ill health poor yield form CSF I & R (add P and E)

``` cryptococcal meningitis what? where mainly? CD4? presentation? culture? antigen? rx? ```

``` fungal mainly in HIV disease CD4 <100 subtle neurological presentation aseptic picture on CSF serum and CSF cryptococcal antigen IV amphotericin B/flucytosine. fluconazole ```

clinical signs of BM (3)

fever stiff neck alteration in consciousness

signs and symptoms of BM (8)

``` headache vomiting pyrexia neck stiffness photophobia lethargy confusion rash ```

who are the signs of BM absent or atypical?

the very young the very old the immunocompromised

Principles of LP

only if clinically feasible measure opening pressure if flow fast treat with antibiotics first

what are CSF pleocytosis not

``` tubes for CSF interpretation 1 2 3 4 ```

1 - haem: cell count, differential 2 - micro: gram stain, cultures 3-chemistry: glucose, protein 4- haem

microbiology diagnosis of BM

blood cultures throat swab (meningococcal) blood ADTA for PCR (meningococcal) CSF - micro, biochem, culture, antigen detection, PCR

when is bm culture negative

pre LP use of AB lowers gram stain positivity by 20% and culture positivity in children in 90-100% of px within 24-36 hours of AB treatment CSF becomes culture negative and there is no significant change in cell count/chemistry

CSF in BM

``` WBC >2000 neutrophils >1180 protein >220 Glucose <34 Glucose (CSF/serum) <0.23 ```

what is aseptic meningitis | CSF?

non-pyogenic BM | low number of WBC, minimally elevated protein, normal glucose

indications for hospital admission

signs of meninges irritation impaired conscious level petechial rash any illness esp headache and in contact with meningococcal infected px even if they have had prophylaxis

On arrival into hospital

bloods and coag screen initial treatment throat swab disrupt and swab any rash

indication for CT scan

all patients with papilloedema or focal neurological signs, immunocompromised, history of CNs disease, new onset seizure, abnormal level of consciousness

warning signs in BM

``` marked depressive conscious level GCS <12 or fluctuating focal neurology seizure before or at presentation shock bradycardia and hypertension papilloedema ```

LP indications | what should be given first

suspected meningitis or clinical dx or meningococcal infection with typical meningococcal rash ABs

rx for BM

IV ceftriaxone (IV ampicillin/amox for listeria) PA - chloramphenicol IV 25mg/kg 6hourly and vanc IV 500mg 6 hourly or 1g 12 hourly. If listeria - co-tramoxazole Dexomethason before or with the first dose of AB 10mg IV

when should steroids not be given

post surgical meningits severe immunocomprimised meningococcal or septic shock

meningococcal disease on admission assessing prognosis

``` haemorrhagic diatheses deteriorating conscioussness multi organ failure rapidly developing rash >60 ```

meningitis all types on admission

``` tachycardia GCS<12 on admission Low GCS, cranial nerve palsy seizures within 24 hours hypotension >60 ```

management of low GCS or fluctuating consciousness level

secure airway and start high flow oxygen IV 3g ceftriaxone (add amox if over 55 to cover listeria) IV corticosteroids

prophylaxis for BM

600mg rifampicin PO 12 hourly 4 doses in adults and over 12s, 10mg/kg IV 12 hourly 4 doses for 3-11 months OR 500mg cipro PO for adults and >12s OR 250mg ceftriaxone IM single dose in adults and 125mg IV as a single dose in under 12s