Infections Of The CNS Flashcards

1
Q

List the possible route of infection for meningitis

A

Blood-borne
Parameningeal suppuration e.g. otitis media, sinusitis
Direct spread through defect in the duration e.g. trauma
Direct spread through cribriform plate (rare)

CSF stile, immune system can’t cope

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2
Q

List the complications alongside meningitis

A
death
subdural collection
cerebral vein thrombosis
hydrocephalus 
9-15% deafness (Hib)
convulsions
visual/motor/sensory deficit
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3
Q

Below are the common organisms that cause meningitis, what group are they commonly found in?

Neisseria meningitidis
Streptococcus pneumoniae
Hib
Escherichia coli
Listeria monocytogenes
A

neisseria meningitidis - children/young adults

strep pneumoniae - elderly and children <2 yrs
Hib - children <5yrs
e.coli - neonates
listeria - neonates/immunocompromised

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4
Q

What are the levels of protein
IgG
lymphatics in cerebrospinal fluid?

A

LOW

and no lymphatics

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5
Q

Describe the inflammatory process in meningitis

A

Release inflammatory mediators - TNF, IL-1&8, PAF and NO

neutrophils migrate to the CSF, release proteolytic products and toxic O radicals

vascular endothelium is damages, BBB is reduced = alteration of CSF and blood supply dynamics

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6
Q

What symptoms arise in meningitis

where else can these symptoms occur?

A

global headache
neck and back stiffness
nausea and vomiting
photophobia

infections, SAH, malignancy, NSAIDs

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7
Q

What symptoms are found in infants with meningitis (typical signs aren’t present in <18/12)

A
flaccid- later opisthotonus (muscle spasms)
bulging fontanelle due to increased ICP 
fever and vomiting 
strange cry
convulsions
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8
Q

List the physical symptoms of meningitis

A

fever
rash - petechial/purpuric (meningococcal usually)
irritation - photophobia, Kernig’s positive, neck stiffness, Brudzinski’s sign

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9
Q

Why have a lumbar puncture in meningitis?

A

most rapid diagnostic test
distinguish between bacterial and viral

risk of herniation

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10
Q

How does the CSF change in meningitis for bacterial, tuberculous and viral?

leucocytes
neutrophiles
lymphocytes
protein
glucose
A

increase in leucocytes and lymphocytes and neutrophiles

decrease in glucose

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11
Q

What organisms are common in community acquired meningitis?

A

51% s.pneumoniae
37%n.meningitidis
4% l.monocytogenes

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12
Q

What complications are associated with meningococcal disease

A
death 
necrotic lesions
reactive arthritis (young adults)
serositis 
neurological sequelae (rare)
abscess formation (rare)
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13
Q

List the risk factors of a poor outcome with meningococcal disease

A
advanced age
presence of otitis media or sinusitis 
absence of rash
tachycardia
low GCS
positive blood culture 
thrombocytopenia 
low CSF fluid - white cell count
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14
Q

Give the general management of meningitis

A
antibiotics
adequate oxygenation
prevention of hypoglycaemia and hypotraemia 
anticonvulsants 
decrease intracranial hypertension
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15
Q

What makes a good antibiotic for meningitis

A

bactericidal
sufficient penetration into CSF at non-toxic doses

low levels of endotoxin release when organisms killed?

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16
Q

What are the differences between the BBB and the B-CSF barrier

A

BBB - no fenestrations in the endothelium, thick basement membrane, has astrocytes

B-CSF - fenestrated, thin basement membrane, has choroid plexus

17
Q

Penetration of antibiotics into CSF is enhanced by…?

A
high lipid solubility 
low molecular weight 
low degree of ionisation 
high serum concentration 
low degree of protein binding 
meningeal inflammation
18
Q

There are three groups of CSF penetration:
1 penetrate inflamed and non-inflamed at standard dose
2 penetrate inflamed/high dose
3 penetrate poorly

give an example of each

A

1 metronidazole, trimethoprim, sulphonamides

2 benzylpenicillin, cephalosporins, rifampicin, vancomycin, amB

3 gentamicin, cephalosporins, erythromycin, tetracycline

19
Q

What is chloramphenicol used for

A

reserve agen for allergic patients with meningitis

resistance in Hib and pneumococci

20
Q

What is cefotaxime/ceftriaxone used for

A

first line treatment for meningitis in adults and children, NOT for listeria

can be used if someone has a penicillin allergy

21
Q

What is benzylpenicillin used for

A

Best for pneumococcal meningitis
high levels can lower threshold for epileptic fits
not for haemophilus influenze

22
Q

What are the penetration of antibiotics into the brain/blood ratio for

chloramphenicol
cefotaxime/ceftriaxone
benzylpenicillin G

A

9: 1
1: 10
1: 23

23
Q

Roughly how to treat meningitis with antibiotics

A

meningococcus 7
pneumococcus 14
haemophilus 7
listeria 21

if organism is not isolated this should be IV 7-14 days

24
Q

what is the link between meningitis and steroids

A

give steroids prior to antibiotics for beneficial effect

25
Q

What antibiotics are used in phrophylatic for meningitis

A

rifampicin (liver effect)
or
ciprofloxacin (for pregnant women)

26
Q

What vaccines are there for meningitis

A

MenB and MenC

27
Q

What are the presentations for a brain abscess

A
focal neurological signs
raised intracranial pressure
headache
fever
CRP and ESR raised 
(CSF pleocytosis)
28
Q

Name the three ways brain abscess can occur

A

direct spread via venous connections
haematogenous spread
direct implantation

29
Q

Name the three ways a brain abscess can form

A

cerebritis with central inflammation
ring of cerebritis with necrotic centre
capsule formation

30
Q

List some of the bacterial aetiology of a brain abscess

A
strep. milleri
anaerobes
enterobacteriaceae
staph.aureus
polymicrobial
31
Q

Describe the general treatment options for a brain abscess

A

drainage (crainiotomy)
excision via craniotomy
antibiotics

32
Q

List the antibiotic treatments by source:

likely dental, sinus, haematogenous source

likely otogenic source

post-operative/ traumatic

A

1 ceftriaxone and metronidazole (narrow down to benzylpenicillin and met.azole is anaerobic)

2 ceftazidime, benzylpenicillin and metronidazole or
meropenem

3 vancomycin and meropenem

33
Q

How long should brain abscess antibiotic treatment last?

A

high dose
6-8 weeks
IV first then oral