CNS infections Flashcards

1
Q

What are the 2 main infections of the CNS?

A

Meningitis
Encephalitis

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2
Q

What is meningitis?

A

Serious infection of the meninges, the outer membranes covering the brain and spinal cord

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3
Q

What are some of the classifications of meningitis?

A

Acute pyogenic (Bacterial)
Acute aseptic
Acute focal suppurative
Chronic bacterial

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4
Q

Main bacteria in neonatal bacterial meningitis?

A

Listeria monocytogenes
Group B Streptococci
E. coli

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5
Q

Main bacteria in bacterial meningitis of infants

A

H. influenza

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6
Q

Main bacteria in bacterial meningitis of those 10-21

A

Neisseria meningitidis (Meningococcal)
Streptococcus pneumoniae (Pneumococcal)

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7
Q

Main bacteria in bacterial meningitis of those 21-65

A

Streptococcus pneumoniae
Neisseria meningitidis

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8
Q

Main bacteria in bacterial meningitis in those over 65

A

Streptococcus pneumoniae
Listeria monocytogenes

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9
Q

Main bacteria in bacterial meningitis in immunosuppressed patients

A

Listeria monocytogenes

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10
Q

Main bacteria in bacterial meningitis in those who have undergone neurosurgery or head trauma

A

Staphylococcus
Gram negative bacilli (Klebsiella pneumoniae, E.coli, Pseudomonas aeruginosa)

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11
Q

Main bacteria in bacterial meningitis in those who have had a fracture of the cribriform plate?

A

Streptococcus pneumoniae

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12
Q

What is the most common form of meningitis?

A

Viral meningitis

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13
Q

What are the most common viruses in meningitis?

A

Enteroviruses (echovirus, Coxsackievirus)
Mumps
HSV
Herpes zoster virus
HIV
Measles
Influenza
Arboviruses

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14
Q

What is meant by aseptic meningitis?

A

Meningitis in which the CSF contains cells but no bacteria

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15
Q

What are some causes of aseptic meningitis?

A

Viral infection
Fungal infection
Parasitic infection
Atypical TB
Lyme disease
Kawasaki disease

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16
Q

How does meningitis occur

A

Microorganisms reach the meninges either by direct extension from the ears, nasopharynx, cranial injury or congenital meningeal defect, or by bloodstream spread

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17
Q

Describe the pathology of acute bacterial meningitis

A
  • The pia-arachnoid is congested with polymorphs
  • A layer of pus forms
  • This may organize to form adhesions, causing cranial nerve palsies and hydrocephalus
  • Cerebral oedema occurs in any bacterial meningitis
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18
Q

Give the characteristics of meningococcal meningitis (Neusseria meningitidis)

A
  • Found in the throats of healthy carriers
  • Symptoms are caused by endotoxins
  • Occurs mostly in young children
  • Can cause local disease or septicaemia
  • 12 capsular groups of meningococcus
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19
Q

Give the characteristics of H.influenza meningitis?

A
  • Part of the normal throat microbiota
  • Requires blood factor for growth
  • 6 sub-types (b is most common and is vaccinated against)
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20
Q

Give the characteristics of pneumococcal meningitis (Streptococcus pneumonia)

A
  • Commonly found in the nasopharynx
  • Most common in hospitalised patients, CSF fractures, diabetics, alcoholics and children
  • Rare but high mortality
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21
Q

Give the characteristics of listeria monocytogenes meningitis

A
  • Gram +ve bacilli
  • Commonly bacteraemic
  • More common in neonates and immunosuppressed patients
22
Q

What is the antibiotic of choice against listeria monocytogenes meningitis?

A

IV ampicillin/amoxicillin

23
Q

Give the characteristics of tuberculous meningitis

A
  • Usually caused by a reactivation of TB in the elderly
  • Poor yield in CSF
  • High morbidity
  • Treated with RIPE
24
Q

Give the characteristics of cryptococcal meningitis

A
  • Fungal
  • Mainly seen in HIV
  • Subtle neurological presentation
25
Q

How is cryptococcal meningitis managed?

A

IV amphoteracinB
Fluconazole

26
Q

Give the pathology of chronic meningitis

A
  • The brain is covered in a viscous grey–green exudate with numerous meningeal tubercles
  • Adhesions are invariable
  • Cerebral oedema occurs in any bacterial meningitis
27
Q

Give the pathology of viral meningitis

A
  • In viral meningitis there is a predominantly lymphocytic inflammatory cerebrospinal fluid (CSF) reaction without pus formation, polymorphs or adhesions
  • There is little or no cerebral oedema unless encephalitis develops
28
Q

How does meningitis present

A

Triad:
- Headache
- Neck stiffness
- fever
Also:
- Photophobia
- Vomiting

29
Q

What are some special features of acute bacterial meningitis?

A

Sudden onset of symptoms with rigours and high fever
Also non-blanching rash

30
Q

What is meningoencephalitis?

A

Meningitis with encephalitis

31
Q

What is the main test used in meningitis?

A

Lumbar puncture

32
Q

What tests are performed on lumbar puncture in meningitis?

A
  • Tube 1 - Haematology - Cell count, differential
  • Tube 2 - Microbiology - Gram stain, cultures
  • Tube 3 - Chemistry - Glucose, protein
  • Tube 4 - Haematology - Cell count, differential

White blood cell count and differential, Gram stain, glucose, protein, lactate, culture, and meningococcal and pneumococcal polymerase chain reaction (PCR)

33
Q

What are some of the markers which are highly predictive of meningitis?

A
34
Q

What is the management of viral meningitis?

A

Treatment is generally supportive - self-limiting condition lasting 4–10 days

35
Q

Treatment of bacterial meningitis in adults

A

IV Ceftrioxone 2g BD
+
IV Dexamethasone 10mg QDS (with 1st Cef dose for 4 days)

36
Q

Treatment of bacterial encephalomeningitis in adults?

A

IV Ceftrioxone 2g BD
+
IV Dexamethasone 10mg QDS (with 1st Cef dose for 4 days)
+
IV Aciclovir 10mg/kg TDS

37
Q

Treatment of bacterial meningitis in those over 60 or those who are immunocompromised

A

IV Ceftrioxone 2g BD
+
IV Dexamethasone 10mg QDS (with 1st Cef dose for 4 days)
+
IV Amoxicillin 2g every 4 hours

38
Q

Who should not be given steroids in bacterial meningitis?

A

Post-surgical meningitis
Severe immunocompromise
Meningococcal or septic shock
Those hypersensitive to steroids

39
Q

Treatment of bacterial meningitis in children <3 months

A

Cefotaxime + Amoxicillin

40
Q

Treatment of bacterial meningitis in children >3 months

A
  • > 3 months 1st dose Cefotaxime followed 6 hours later with once daily Ceftriaxone
  • +/- Dexamethasone IV starting before or with first dose of antibiotic
41
Q

What are some possible complications of meningitis?

A

Purulence (At brain base or around nerves)
Invasion (Erosion of pia)
Cerebral oedema
Ventriculitis
Hydrocephalus
Limb loss
Deafness
Blindness
Cerebral palsy
Quadriplegia

42
Q

What is encephalitis?

A

Acute inflammation of the brain parenchyma

43
Q

What are the most common bugs of encephalitis?

A

Usually viral - usually HSV, VZV and other herpes group viruses, HHV-6, 7, enteroviruses and adenovirus

44
Q

What is limbic encephalitis?

A

A form of antibody-mediated encephalitis which may be associated with underlying malignancy or autoimmune disorder

45
Q

How does encephalitis present?

A
  • Fever (90%)
  • Meningism
  • Personality and behavioural change, which progresses to a reduced level of consciousness and even coma
  • Seizures (focal and generalised)
  • Focal neurological deficits, such as speech disturbance
46
Q

What investigations are required in encephalitis?

A
  • MRI - bilateral medial temporal lobe involvement
  • EEG
  • CSF
    • Viral - elevated lymphocytes, viral detection by CSF PCR
    • Limbic - antibodies may be identifiable
47
Q

How is suspected HSV and VZV encephalitis managed?

A

Immediate IV Acyclovir

48
Q

How may limbic encephalitis be managed?

A

Treat tumour
Immunsuppression

49
Q

What are the options for contact prophylaxis for meningitis?

A
  • Rifampicin PO
  • Ciprofloxacin PO
  • Ceftrioxone IM
50
Q
A