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Year 5 😊✌🏼 > CNS infection > Flashcards

CNS infection Flashcards

1
Q

Routes of entry for a CNS infection

A

haematogenous spread (commonest)
direct implantation
local extension
PNS into CNS

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2
Q

Types of CNS infection

A

meningitis
encephalitis
myelitis (spinal cord)
Neurotoxin (CNS?PNSS)

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3
Q

Commonest way to get CNS infection

A

haematogenous spread

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4
Q

what causes neurological damage in meningitis?

A
  • direct bacterial toxicity
  • indirect inflammatory process and cytokine release and oedema
  • stick, seizures, and cerebral hypo perfusion
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5
Q

mortality of meningitis

A

10%

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6
Q

What % of poeple who have meningitis are left with neurological sequelae?

A

5%

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7
Q

Pathogens causing meningitis

A

Descending common:

neisseria meningitidis (meningococcus - gram negative diplococci)
streptococcus pneumonia (gram + diplococci)
haemophilus influenzae

listeria monocytogenes (gram-positive rods)
GBS
E coli

staphylococcus aureus
TB
treponema pallidum
cryptococcus neoformans
candida
coccidioidess immitis
histoplassma capsulatum
blastomycosis dermatiiidis

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8
Q

three commonest causes of meningitis

A

neisseria meningitides (meningococcus)
streptococcus pneumonia
haemophilus influenzae

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9
Q

N. meningitidis

A
  • 50% meningitis
  • infectious cause of childhood death in all countries
  • pathogenic strains are found in 1% carriers, transmitted from person to person from asymptomatic carriers
  • septicaemia - non-blanching petechial rash (develops in 80% children)

meningitis in 50%
septicaemia in 7-10%
septicaemia and meningitis 40%

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10
Q

Ix of choice for meningitis?

A

LP

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11
Q

What causes the clinical spectrum in septicaemia?

A

Capillary leak -> albumin and other plasma proteins leads to hypovolemia.

Coagulopathy -> leads to bleeding and thrombosis.
- Endothelial injury results in platelet-release reactions
- The protein C pathway.
- Plasma anticoagulants.

Metabolic derangement -> particularly acidosis

Myocardial failure….multi-organ failure.

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12
Q

acute meningitis sx

A

fever
reduces GCS
neck stiffness
photophobia
N&V
lethargy
+ve Kernig +/- Brudzinski sign

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13
Q

chronic meningitis - common pathogen and presentation

A
  • TB
  • gradual manifestation, intermittent fever
  • involves the meninges and basal cisterns of the brain and spinal cord.
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14
Q

when is chronic meningitis more common?

A

in immunosuppressed

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15
Q

aseptic meningitis - what is it?

A

meningitis in the absence of bacteria

-> most likely viral

causes headache, stiff neck and photophobia (and can have a nonspecific rash)

self limiting and resolves in 1-2 weeks

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16
Q

Most common cause of viral meningitis?

A

enterovirus (coxsackievirus group B, echoviruses, polio) - 80-90%

HSV 1&2
mumps
measles
EBV/CMV
VZV

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17
Q

What is encephalitis?

A

inflammation of the brain parenchyma

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18
Q

Commonest cause of encephalitis

A

flaviridae e.g. western nile virus are becoming the leading cause of encephalitis internationally

togavirus family
flavivirus family
bunyavirus family

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19
Q

Commonest causes of encephalitis

A

VIRAL (flaviviridae e.g. west nile virus, toga- and bunyaviriuses.)

bacterial: listeria monocytogenes

amoebic encephalitis: naegleria fowleri (warm water) Acanthamoeba species, and Balamuthia mandrillaris (brain abscess, aseptic or chronic meningitis)

Toxoplasmosis (kittens)

Viral: flaviridae

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20
Q

Mx of brain abscess

A

drain it (neurosurgery)

antibiotics (xxx)

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21
Q

what causes brain abscesses? (routes)

A

direct extension form otitis media/mastoiditis/paranasal sinuses

endocarditis/ haematogenously

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22
Q

Pathogens causing abscesses

A

Streptococci (both aerobic and anaerobic)
Staphylococci,
Gram-negative organisms. (particularly in neonates)
Mycobacterium tuberculosis
fungi
parasites
Actinomyces and Nocardia species

different to meningitis and encephalitis because of different route of infection

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23
Q

spinal infections - causes

A

Direct open spinal trauma, from infections in adjacent structures, from hematogenous spread of bacteria to a vertebra.

24
Q

spinal infecitons - mangement

A
25
Q

RFs for spinal infection

A

Advanced age
Intravenous drug use
Long-term systemic steroids
Diabetes mellitus
Organ transplantation
Malnutrition
Cancer

26
Q

Ix for CNS infection

A

MRI > CT (better at detecting parenchymal abnormalities such as abscesses and infarctions)

CSF samaple
brain tissue

27
Q

why is MRI superior to CT in

A

In CT scan you cannot comment on the meninges at all

better at detecting parenchymal abnormalities such as abscesses and infarctions

28
Q

Why would you do a CT in CNS infections?

A

to check for any raised ICP (GMC risk if someone has coning without CT scan) - pre LP

29
Q

What % people carry strep pneumoniae in their nassopharynx?

A

1 in 5

30
Q

What % people carry meningococcus in their nasopharynx?

A

1 in 10

31
Q

Mx of meningitis

A

ceftriaxone 2g IV BD

if older/immunocompromised: add amoxicillin 2g IV 4-hourly (to cover for listeria)

32
Q

Mx of encephalitis

A
33
Q

Meningoencephalitis

A

inflammation of meninges and
brain parenchyma

34
Q

What can chronic TB meningitis progress to

A

Can result in tuberculous granulomas, tuberculous abscesses, or cerebritis

35
Q

Incidence of chronic Tb meningitis in Africa + mortality of chronic Tb meningitis

A

544 per 100,000

mortality: 5.5 deaths per 100,000 persons

36
Q

Commonest infection of the CNS

A

aseptic meningitis

37
Q

What age group does aseptic meningitis most commonly occur in?

A

children younger than 1 year

38
Q

commonest causes of aseptic meningitis

A

Enteroviruses
- coxsackievirus B
- echoviruses

39
Q

How is encephalitis transmitted?

A

Commonly person to person

Via vectors:
- mosquitoes
- lice
- ticks

40
Q

Toxoplasmosis

A

Can cause infectious encephalitis

An obligate intracellular protozoal parasite, Toxoplasma gondii.

Via the oral, transplacental route or organ transplantation.

Severe infection in immunocompromised
patients.

Affected organs include the gray and
white matter of the brain, retinas,
alveolar lining of the lungs, heart,
and skeletal muscle.

41
Q

Common form of vertebral infection

A

Pyogenic vertebral osteomyelitis common form of vertebral infection.

42
Q

What can happen if spinal infections are left untreated?

A
  • permanent neurologic deficits
  • significant spinal deformity
  • death.
43
Q

CSF studies - what do you look at>

A

color/clarity
cell counts
chemistry (protein, glucose)
stains (gram/auramine (ZN), india ink)
culture (bacterial, fungal, TB)
PCR

44
Q

Normal CSF - CSF studies

A

Appearance: clear
Cells x 10^6/L: 0-5 leukocytes
Gram stain: -ve
Protein g/L: 0.15 - 0.4
Glucose mmol/L: >60% blood glucose level

45
Q

Purulent meningitis CSF studies + ddx

A

Appearance: turbid
Cells x 10^6/L: 100-10,000 polymorphs (raised)
Gram stain: +ve
Protein g/L: 0.5-4.0 (high)
Glucose mmol/L: <60% blood glucose (low)

ddx bacterial meningitis (?meningococcus, ?pneumococcus, ?listeria)

46
Q

Aseptic meningitis CSF studies

A

Appearance: clear or slightly turbid
Cells x 10^6/L: 15-1000 lymphocytes
Gram stain: -ve
Protein g/L: 0.5-1.0
Glucose mmol/L: >60% blood glucose level

ddx
viral meningitis
partially abx treated meningitis
encephalitis
brain abscess
TB/fungal meningitis

47
Q

TB meningitis CSF studies

A

Appearance: clear or slightly turbid
Cels x 10^6/L: 30 - 1000 lymphocytes or some polymorphs
Gram stain: -ve (scanty acid fast bacilli)
Protein g/L: 1.0 - 6.0
Glucose mmol/L: <60% blood glucose

ddx
TB meningitis
brain abscess
cryptococcal meningitis

48
Q

Limitations of CNS infection diagnostics

A

MRI oedema pattern and moderate mass effect cannot be differentiated from tumor or stroke or vasculitis in some patients.

Infections in early stages and serological tests.

Amount of CSF.

PCR techniques.

Methods to detect amoebic infections.

Availability of good laboratory technique.

49
Q

Mx of meningo-encephalitis (generic therapy)

A

Aciclovir 10 mg/kg IV TDS

Ceftriaxone 2g IV BD

If >50yo or immunocompromised add amoxicillin 2g IV 4 hourly

50
Q

ABx for listeria meningitis?

A

amoxicillin 12 g (2g IV 4 hourly)

plus aminoglycoside

51
Q

ABx for H influenzae meningitis/CNS infection

A

cefotaxime 12g/d

OR

ceftriaxone 4g/d

52
Q

abx for pseudomonas CNS infection

A

meropenem 6g/d

OR

ceftazidime 6g/d

53
Q

gram -ve bacilli abx in CNS infection

A

Cefotaxime 12 g/d
or
Ceftriaxone 4g/d

54
Q

ABx for GBS CNS infection

A

Pen G
or
Amoxicillin

[plus aminoglycoside]

55
Q

ABC for S.pneumoniae/N.meningitidis CNS infection

A

Pen G 18-24 mu/d
or
Amoxicillin 12 g/d
or
Ceftriaxone 4 g/d
or
Chloro 75-100 mg/kg/d

Year 5 😊✌🏼 (53 decks)

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