CNS infections* Flashcards
What type of meningitis shows a thick layer of suppurative exudate that covers the leptomeninges over the surface of the brain
pyogenic (bacterial)
microscopically what does pyogenic meningitis show
neutrophils in the subarachnoid space
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
how to treat viral encephalitis caused by herpex simplex
high dose IV aciclovir
how to treat viral encephalitis caused by varicella zoster and who does it occur in
history of shingles
high dose acyclovir
what other viruses can cause viral encephalitis
CMB, HIV, measles
what are some travel related causes of viral encephalitis
west nile, japanese B encephalitis, tick borne encephalitis
what are some occupational related causes of encephalitis
rabies
clinical features of encephalitis (9)
insidious onset, sometimes sudden stupor coma meningismus seizures partial paralysis confusion psychosis speech &memory problems
investigations for encephalitis and what should be done if there is a delay
LP, EEG, MRI
start acicilovir pre emptive
how do cerebral abscesses arise
spread from intracranial infection such as mastoiditis but usually via blood stream
common causes of cerebral abscesses
congenital HD, pulmonary AV fistulas, bronchiectasis, lung abscess, bacterial endocarditis
common organisms in cerebral abscesses and which is the commonest
strep viridian’s (commonest)
SA, haemolytic strep, enterbacteriacie, bacteroids and other anaerobes
what are the organisms in immunosuppressed for cerebral abscesses
fungal or toxoplasmic gondii abscesses may occur
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
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
organisms in bacterial meningitis
neonates - listeria, group b strep, EColi children - HI 10-21-meningococcal 21 onwards - pneumococcal>meningococcal elderly - pneumococcal>listeria
risk factors for listers, staph GNR and pneumococcal acquired bacteria meningitis
decreased CMI
neurosurgery/open head trauma
fracture of the cribriform plate
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
bm
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
