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PathY5 > CNS infections and meningitis > Flashcards

CNS infections and meningitis Flashcards

1
Q

What are the four routes of entry?

A

Haematogenous spread
Direct implantation
Local extension
PNS into CNS

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2
Q

What are the signs and symptoms of meningitis?

A

Fever
Headache
Stiff neck
Disturbance of brain function

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3
Q

What are the causative organisms in meningitis?

A 
N. meningitidis
S. pneumoniae
H. influenzae
TB
Viruses
Fungus- cryptococcus neoformans
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4
Q

What does encephalitis cause?

A

Disturbance of brain function

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5
Q

What organisms are implicated in encephalitis?

A 
Rabies
Arboviruses
Trypanosoma species
Prions
Amoeba
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6
Q

What is myelitis?

A

Disturbance of nerve transmission

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7
Q

What causes myelitis?

A

Poliovirus (poliomyelitis)

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8
Q

What do neurotoxins cause?

A

Paralysis both rigid (tetanus) and flaccid (botulism)

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9
Q

What organism causes neurotoxin related paralysis?

A

Clostridium tetani

Clostridium botulinum

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10
Q

What is affected in meningitis?

A

inflammatory process of meninges and CSF

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11
Q

What is affected in meningoencephalitis?

A

inflammation of meninges and

brain parenchyma

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12
Q

What causes neurological damage in meningitis?

A

Direct bacterial toxicity.

Indirect inflammatory process and cytokine release and oedema.

Shock, seizures, and cerebral hypoperfusion.

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13
Q

What is the mortality of meningitis?

A

Mortality rate around 10%

In the UK, (Morbidity) ~ 5% of meningitis survivors have neurological sequelae, mainly sensorineural deafness.

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14
Q

How do you class meningitis?

A

Acute - bacterial
Chronic - TB, syphilis, cryptococcal (Immunodef)
Aseptic - Viral

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15
Q

What most commonly causes acute meningitis?

A
  1. Neisseria meningitidis
  2. Streptococcus pneumoniae
  3. Haemophilus influenzae

Less common:
Listeria monocytogenes
Group B Streptococcus
Escherichia coli

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16
Q

What is the aetiology/ pathological sequelae of meningitis through N. meningitidis?

A

Infectious cause of childhood death in all countries.

Transmission is person-to-person, from asymptomatic carriers.

Pathogenic strains are found in only 1% of carriers.

Through nasopharyngeal mucosa in a susceptible individual.

Cause infections in less than 10 days.

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17
Q

What type of rash is associated with meningococcal septicaemia?

A

A nonblanching rash (petechial or purpuric) develops in 80% of children.

A maculopapular rash remains in 13% of children, and no rash occurs in 7%.

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18
Q

How many people get septicaemia with N meningitidis?

A

50% of cases have meningitis
7-10% have septicemia
40% have septicemia AND meningitis

The clinical difference between septicemia and meningitis is important because patients who present with shock are treated
differently than patients who present primarily with increased intracranial pressure (ICP).

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19
Q

What 4 processes lead to the clinical spectrum associated with 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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20
Q 
What is the:
Epidemiology
Aetiology 
Histopathology 
of TB meningitis?
A

Incidence: 544 per 100,000 population in Africa.

More common in patients who are immunosuppressed.

Mortality was 5.5 deaths per 100,000 persons.

Involves the meninges and basal cisterns of the brain and spinal cord.

Can result in tuberculous granulomas, tuberculous abscesses, or cerebritis

21
Q 
What is the:
Epidemiology
Aetiology 
Histopathology 
of aseptic meningitis?
A

Aseptic meningitis is the most common infection of the CNS.

Patients with aseptic meningitis have headache, stiff neck, and photophobia.

A nonspecific rash can accompany these symptoms.

Coxsackievirus group B and echoviruses are responsible for 80-90% cases in which a causative organism of aseptic meningitis is identified.

It most frequently occurs in children younger than 1 year.

The clinical course of aseptic meningitis is self-limited and resolves in 1-2 weeks.

22
Q

What are the most important viral causes of CNS infection?

A

Enteroviruses (all ages- summer to autumn)
HSV 1/2 (adults summer - autumn)
Coxsackie Virus B

23
Q

Which viruses cause CNS infections in children/ YA?

A 
Mumps
Measles
Varicella-zoster
Epstein-Barr virus/ cytomegaloviruses
Other (myxoviruses, paramyxoviruses, adenoviruses)
24
Q

What is the typical mode of transmission in encephalitis?

A

Person to person or vector (lice, mosquito, ticks)

25
Q

What are the viral causes of encephalitis?

A 
Arboviruses
Western equine encephalitis
St. Louis encephalitis 
California encephalitis 
Eastern equine encephalitis
Rabies
26
Q

What is most likely to cause bacterial encephalitis?

A

Listeria monocytogenes

27
Q

What organisms cause amoebic encephalitis?

A

Naegleria fowleri

Habitat – warm water

Acanthamoeba species, and Balamuthia mandrillaris,
brain abscess, aseptic or chronic meningitis.

28
Q

What is toxoplasmosis?

A

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

29
Q

What may cause a brain abscess?

A

otitis media/mastoiditis/paranasal sinuses

endocarditis/haematogenously

30
Q

Which organisms are associated with brain abscesses?

A

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

31
Q

Why are spinal infections bad?

A

Pyogenic vertebral osteomyelitis common form of vertebral infection.

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

Left untreated, it can lead to permanent neurologic deficits, significant spinal deformity, or death.

32
Q

What are the RFs for spinal infections?

A 
Advanced age
Intravenous drug use
Long-term systemic steroids
Diabetes mellitus
Organ transplantation
Malnutrition
Cancer
33
Q

Which diagnostic modality would be useful in diagnosis?

A

MRI > CT if soft tissue issue (like abscesses and infarctions)

CNS infection = CSF sampling and biopsy

34
Q

What can you order with CSF?

A 
Color/Clarity
Cell counts
Chemistry			(Protein/ Glucose)
Stains	 			(Gram/ Auramine/ India Ink)
Cultures 
\+/- Antigen screens
PCR
35
Q 
Describe the 
1. appearance 
2. cells present 
3. gram stain/ Ag test 
4. protein 
5. glucose 
in a normal CSF sample
A
  1. Clear
  2. 0-5 leukocytes
  3. negative staining/Ag
  4. 0.15-0.4 g/L
  5. 2.2 -3.3 mmol/l (60% blood glucose level)
36
Q 
Describe the 
1. appearance 
2. cells present 
3. gram stain/ Ag test 
4. protein 
5. glucose 
in purulent meningitis (e.g. bacterial)
A
  1. Turbid
  2. 100 - 200 polymorphs
  3. positive
  4. 0.5-3.0 g/l
  5. 0-2.2
37
Q 
Describe the 
1. appearance 
2. cells present 
3. gram stain/ Ag test 
4. protein 
5. glucose 
in Aseptic meningitis
A
  1. clear or slightly turbid
  2. 15 - 500 lymphocytes
  3. Negative
  4. 0.5-1.0 g/l
  5. normal
38
Q 
Describe the 
1. appearance 
2. cells present 
3. gram stain/ Ag test 
4. protein 
5. glucose 
in TB meningitis
A
  1. clear or slightly turbid
  2. 30 - 500 lymphocytes / polymorphs
  3. Negative - scantly AF bacilli
  4. 1.0-6.0 g/l
  5. 0-2.2
39
Q

What are the limitations of 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.

40
Q

What drugs do you give meningitis pts?

A

Ceftriaxone 2g iv bd

If >50yrs or immunocompromised add:
Amoxicillin 2g iv 4hourly

41
Q

What drugs do you give meningoencephalitis pts (generically)?

A

Aciclovir 10mg/kg iv tds

Ceftriaxone 2g iv bd

If >50yrs or immunocompromised add:
Amoxicillin 2g iv 4hourly

42
Q

What is the recommended therapy for S pneumoniae or N meningitidis meningitis?

A

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

43
Q

What is the treatment for H influenzae and G-ve bacilli?

A

Cefotaxime 12 g/d or Ceftriaxone 4g/d

44
Q

What is the treatment for listeria meningitis?

A

Ampicillin 12 g/d or Pen G 18-24 mu/d

[plus aminoglycoside]

45
Q

What is the treatment for Gp B strep meningitis?

A

Pen G 18-24 mu/d or Ampicillin 12 g/d

[plus aminoglycoside]

46
Q

What is the treatment for pseudomonas meningitis?

A

Meropenem 6g/d or Ceftazidime 6g/d

47
Q

What adjunct therapy is available?

A

Level of care

Corticosteroids

? Repeat lumbar puncture

Public health

48
Q

What class of meningitis is meningococcal meningitis?

A

Acute

49
Q

Which pathogen is revealed by india ink?

A

Cryptococcus (neoformans)

PathY5 (98 decks)

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