CNS infection Flashcards
Why are CNS infections an emergency? define the following: Encephalitis Meningitis Meningoencephalitis Encephalomyelitis
-brain and spinal do not regenerate
-might cause brain herniation and death
cord compression and necrosis with paralysis
-brain inflammation
inflamed meninges
inflamed meninges and cerebral tissue
inflammation of brain and spinal cord
define the following:
- acute pyogenic meningitis
- acute aseptic meningitis
- acute focal supportive infection
- chronic bacterial infection
- Acute encephalitis
- bacterial, rapidly developing inflammation of meninges & subarachnoid space
- viral
- brain abscess, subdural and extradural empyema
- TB
- infection of the brain parenchyma
acute pyogenic meningitis
-morphology? (3)
-thick layer supportive exudate covering leptomeninges over the surface of the brain
exudate in basal and convexity
microscopically: neutrophils in subarachnoid space
Viral meningitis
- causative organisms?
- presentation? (2)
- investigations? (3)
- treatment? (1)
-enteroviruses, e.g. cocksackie
-headache
photophobia
-viral stool culture, throat swab PCR CSF (lymphocytic)
-supportive (paracetamol, fluids, rest)
viral encephalitis
- causative organism?
- related to what?
- treatable?
- presentation?
- investigations?
- findings on MRI
-herpes simplex (RAPID RECOGNITION NEEDED, tx is high dose aciclovir)
also varicella zoster, CMV, HIV and measles
- travel
- only HS and VZ- high dose aciclovir
-insidious onset meningismus stupor, coma seizures, partial paralysis Confusion psychosis speech/memory symptoms
- LP, EEG, MRI
- generally see inflammation in the temporal lobes
Abscess
- appearance in MRI?
- routes if infection?
- presentation?
- treatment?
- ring enhancing lesion in parenchyma of the brain
- blood, heart, bronchiectasis
- headahces, focal neurological deficit, seizure
- surgery and drainage
bacterial meningitis
- causative organisms in following groups?
- neonates
- children
- 10-21
- 21+
- elderly
- immunocompromised
- basilar skull fracture
- head trauma/neurosurgery
- CSF shunt
- AIDS
- listeria, group B strep, E.coli
- H.influenza
- Meningococcal
- pneumococcal > meningococcal
- Pneumococcal > listeria
- S. pneumoniae, N. meningitidis, Listeria, aerobic GNR
- S. pneumoniae, H. influenzae, beta-hemolytic strep group A.
- S. aureus, S. epidermidis, aerobic GNR
- S. epidermidis, S. aureus, aerobic GNR, Propionibacterium acnes
- Cryptococcus neoformans
Meningococcal meningitis (Neisseria Meningitis)
- population group?
- pathway of infection?
- CSF signs?
- symptoms occur due to what?
- young children
- can be carries in throats of healthy individuals, gain access via blood stream
- bacteria found in leukocytes in CSF
- enterotoxin
Hemophilus influenza Meningitis
- population group?
- vaccine?
- part of normal throat microbiota, most common cause in children under 4 is H.influenzae type b
- vaccine available, against the capsular polysaccharide
-
Streptococcus pneumoniae Meningitis
- normally found where
- population groups?
- vaccines?
- nasopharynx
- hospitalised patients, CSF skull fractures, DM, alcoholics, young children
- yes, conjugated and fro pneumococcal pneumonia
Listeria monocytogenes
- gram stain?
- pathway of infection?
- population group?
- treatment?
- gram + bacilli
- bactereamic meanly
- noenates, >55, immunosuppressed
- IV ampicillin, amoxicillin
Tuberculous meningitis
- population group?
- symptoms?
- treatment?
- elderly with reactivated TB
- non specific, weight loss, anorexia, fever, sweats
- isoniazid + rifampicin
CRYPTOCOCCAL MENINGITIS
- organism type?
- in what population?
- presentation?
- CSF appearance?
- treatment?
- fungus
- HIV, CD4< 100
- nuerological presentation
- aseptic picture, do serum and CSF cryptococcal antigen
-IV amphotericin B/lfucytosine
fluconazole
clinical signs of bacterial meningitis? (3)
-symptoms? (8)
fever
stiff neck
Altered level of consciousness
-headache vomiting pyrexia neck stiffness photophobia lethargy confusion non-blanching purpuric rash
signs might be atypical in the very young or very old
LP- principles
- when should it be performed?
- contraindicated in?
- what tests should be done on collected CSF?
- needs to be done promptly, If prolonged wait then start antibiotics
- raised ICP, coning (brain herniation) might occur
-Tube 1: haematology- cell count, differential
Tube 2: Microbiology- gram stain, cultures
Tube 3: chemistry- glucose, protein
Microbial Dx of meningitis
- investigations? (4, 5)
- complications?
blood cultures throat swab Blood EDTA for PCR LP- CSF \+ microscopy biochemistry culture antigen detection PCR
-10-15% of bacterial meningitis culture neg
as can be lowered by Pre-LP use of oral antibiotics
Describe the CSF findings for the following infections:
Viral
Bacterial
TB
(include: cells, gram stain, bacterial antigen detection, protein, glucose)
Viral lymphocytes negative negative normal/slightly high usually normal
Bacterial polymorphs positive positive high less than 70% blood glucose
TB lymphocytes positive or negative negative high or very high protein less than 60% blood glucose
Other causes for neutrophilic pleocytosis & low CSF glucose? (bar bacterial meningitis)
early viral meningitis parameningeal foci/ cerebritis leakage of brain abscess amoebic meningoencephalitis TB meningitis Chemical meningitis Behcet syndrome Drug induced (NSAIDs)
Aseptic meningitis
- what is it?
- CSF findings? (3)
- DDx? (infections 9, non-infectious 6)
- non-pyogenic bacterial meningitis
- low WBC, minimally elevated protein, normal glucose
-HSV 1 and 2 Syphilis Listeria (occasionally) Tuberculosis Cryptococcus Leptospirosis Cerebral malaria African tick typhus Lyme disease
Carcinomatous Sarcoidosis Vasculitis Dural venous sinus thrombosis Migraine Drug (Co-trimoxazole, IVIG, NSAIDS)
Acute adult bacterial meningitis
- prehospital management? (1)
- initial management? (6)
- When is CT indicated? (6)
- poor prognostic indicators? (7)
- empirical antibiotic therapy?
-pre-hopsital antibiotics: Penicillin
-After ABCDE:
If LP cannot be done in the first hour, antibiotics must be given immediately after blood cultures have been taken
Blood cultures & coag screen
Lumbar puncture
Dexamethasone 10mg IV
Ceftriaxone OR Cefotaxime 2g IV immediately following LP
CT scan normally not indicated
Careful fluid resuscitation (avoid fluid overload)
+ throat swab & swab purpuric lesions
-urgent CT prior to LP in papilloedema, immunocompromised, new onset seizure, hx CNS disease, abnormal consciousness level or focal neurological signs
-marked depressed consciousness focal neurology seizure shock bradycardia & hypertension Papilloedema
-IV ceftriaxone 2g bd
+ IV ampicillin/amoxicillin 2g ads if listeria suspected
penicillin allergy:
chloramphenicol iv 25 mg/kg 6-hourly with vancomycin iv 500 mg 6-hourly or 1g 12-hourly.
listeria- Co-trimoxazole
Why do we use dexamethasone
-dose?
both the infection and the antibiotics (fragmented cell wall contents) cause oedema so want to reduce the cytokine inflammatory response and try to keep ICP from raising
-10mg IV 15-20 mins before first dose antibiotics
then every 6 hours, stop after 24 hrs
How is secondary meningitis prevented?
Telephone reporting to Public Health or Health Protection all clinically suspected cases as soon as possible after admission will ensure that appropriate measures to minimise the chance of secondary cases are put in place
inform GPs
contact prophylaxis: give rifampicin
(600mg orally 12-hourly for 4 doses if ever 12, 10mg/kg if 3-11 months)
OR
500mg ciprofloxacin if over 12
OR
250mg ceftriaxone in adults, 125mg in under 12s IV
What organisms can be vaccinated against?
3
Neisseria meningitides (groups A and C)
H.influenzae
Strep pneumoniae
