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MD4001 - Disease > Infections of the CNS > Flashcards

Infections of the CNS Flashcards

1
Q

What are the clinical features of menigitis?

A
  • Headache, sore throat, drowsiness
  • Rapid onset fever, photophobia, neck stiffness
  • Level of consciousness progressively falls
  • Petechial or purpuric rash
  • Intravascular coagulation, endotoxaemia, shock, multi-organ failure, raised intracranial pressure.
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2
Q

What are the other symptoms of meningitis that occur in babies?

A

– Tense or bulging soft spot on their head

– Refusing to feed

– Irritable when picked up, with a high pitched or moaning cry

– A stiff body with jerky movements, or else floppy and lifeless

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3
Q

Define meningitis

A

Inflammation of the meninges

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4
Q

Define encephalitis

A

inflammation of the brain

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5
Q

Define sepsis

A

whole body inflammation

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6
Q

What is the blood brain barrier and how do microbes invade it?

A
  • Blood-brain barrier (BBB)
    • Created by tightly packed endothelial cells lining the blood vessels in the brain.
    • Endothelial cells mechanically supported by thin basement membrane.
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7
Q

What does a breach of the BBB caus?

A

Breach by infectious agents causes encephalitis.

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8
Q

Describe the Blood-CSF barrier

A

– Similar barrier at arachnoid membrane and in ventricles.

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9
Q

What does a breach of the blood-CSF barrier cause?

A

– Breach by infectious agents causes meningitis.

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10
Q

What are the mechanisms of direct spread that result in microbes entering the CNS?

A
  • Sinuses
  • Otitis media
  • Skull fracture
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11
Q

What blood tests should be taken to confirm a diagnosis of meningitis?

A
  • Blood
    • Culture
    • NAAT
    • Glucose
    • FBC
    • UandE
    • Clotting
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12
Q

What CSF tests should be taken to confirm a diagnosis of meningitis?

A
  • CSF
    • WCC
    • gram stain
    • NAAT
    • India Ink
    • Ziehl-Neelsen stain
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13
Q

What are the main bacterial causes of menigits?

A
  • Neisseria meningitidis
  • Haemophilus influenzae
  • Streptococcus pneumoniae
  • Mycobacterium tuberculosis
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14
Q

What are the main viral causes of meningitis?

A
  • Enteroviruses:
    • Echovirus
    • Coxsackie viruses A & B
    • poliovirus
  • Herpes viruses:
    • Herpes simplex 1 & 2
  • Paramyxovirus:
    • Complication of mumps
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15
Q

What are the fungal causes of meningitis?

A

Cryptococcus neoformans

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16
Q

What are the protozoa causes of meningitis?

A
  • Amoebae
  • Naegleria
  • Acanthamoeba
17
Q

What are the main methods used by pathogens to breach the barriers in the body?

A

– Growing across & infecting cells comprising barrier

– Passive transfer in intracellular vacuoles

– Carriage across in infected white blood cells

18
Q

Describe the features of meningitis caused by N. Menungitidis

A
  • Meningococcal disease
  • Gram negative
  • Intracellular diplococus
  • Only infects humans
  • Exists as normal microbiota in nasopharynx
  • Distinct pathogenic serogroups
  • Transmission by droplet spread or direct contact from carriers 5 strains – A, B, C, W135, Y
19
Q

Describe the main features of H. Influenzae meningitis

A
  • Gram-negative
  • Coccobacilli
  • Six capsular serotypes (a-f) known to cause disease
  • Most virulent strain is H. influenzae type b (Hib)
20
Q

What are the main virulence factors of bacteria that cause meningitis?

A
  • Anti-phagocytic polysaccharide capsule
  • Endotoxin
  • IgA protease
  • Outer membrane proteins (OMPs)
  • Pili (fimbriae)
21
Q

What are the main features of Strep. pneumoniae meningitis?

A
  • Pneumococcal disease
  • Chains of cocci
  • Gram positive
  • Exists as normal microbiota in nasopharynx
  • Also causes pneumonia, otitis media
22
Q

What are the main causes of meningitis in neonates?

A
  • Escherichia coli
  • Group B Streptococcus
  • Listeria monocytogenes
23
Q

What are the main causes of meningitis in children under 5?

A

Neisseria meningitidis

Haemophilus influenzae

24
Q

What are the main causes of meningitis in young adults?

A

Neisseria meningitidis

25
Q

What are the main causes of meningitis in older people?

A

Streptococcus pneumoniae

Listeria monocytogenes

26
Q

What are the main causes of meningitis in those who are immunosuppressed?

A

Mycobacterium tuberculosis

Cryptococcus neoformans

27
Q

What are the main complications of bacterial meningitis?

A
  • sepsis
  • intellectual deficit
  • deafness
  • arthritis
  • skin necrosis
28
Q

What are the main vaccines assoicated with bacterial meningitis?

A
  • MenC (meningococcal group C)
  • Hib (Haemophilus influenzae type B)
  • BCG (Mycobacterium tuberculosis)
  • Strep. Pneumoniae (pneumonococcal)
  • MenB (meningococcal group B)
  • Men ACWY (quadrivalent)
29
Q

What is a notifable disease? And why are they important?

A
  • Any disease that is required by law to be reported to government authorities
  • Allows the authorities to monitor the disease
  • Provides early warning of possible outbreaks
30
Q

What are the main features of viral meningitis?

A
  • Milder disease than bacterial but more common
  • NAAT is a valuable diagnostic tool
  • Identify in faeces, urine, CSF, serology
  • No specific treatment
  • Aciclovir (herpes)
  • Use of vaccination (polio)
31
Q

What are the main features of tuberculosis meningitis?

A
  • Frequently associated with miliary TB
  • Usually develops when Rich focus discharges contents in sub-arachnoid space
  • Acid-fast bacilli in CSF smear
  • NAAT and culture from CSF
  • Treated with rifampicin, isonazid, pyrazinamide, ethambutol
  • Vaccination with BCG
32
Q

What are the main features of encephalitis?

A
  • Usually viral in origin
  • Viruses gain access to CNS via blood or neurons
  • Primary encephalitis – First exposure to virus results in virus directly affecting brain / spinal cord
  • Secondary encephalitis – Virus first infects another part of body, then affects CNS when reactivated
33
Q

What are the main causes of encephalitis?

A
  • Cerebral malaria (Plasmodium sp.)
  • Toxoplasma gondii
  • Rabies
  • Herpes simplex virus
  • Prions
  • Mumps virus
  • Polio virus
  • Candida albicans
  • Arboviruses
  • Lyme disease (Borrelia burgdorferi)
  • Japanese encephalitis virus
  • West Nile virus
34
Q

What are the main signs of cerebral dysfunction?

A
  • abnormal behaviour
  • seizures
  • altered consciousness
  • nausea
  • vomiting
  • fever
35
Q

What are the main features of a brain abscess?

A
  • Begin as diffuse inflammation of brain matter progressing to focal lesion
  • Arise from pia mater suppuration
  • Visualised by MRI or CT scans
  • Diagnosed by culture from aspirated pus
36
Q

What are the main causes of brain abscess?

A
  • Predisposing factors
    • Otitis media
    • Mastoiditis
    • Sinusitis
  • Oral-nasopharyngeal microbiota
    • Aerobic (S. aureus, Strep. milleri)
    • Anaerobic (Bacteroides sp., Fusobacterium sp.)
  • Immunocompromised (eg. HIV, transplantation)
    • Protozoa (Toxoplasma gondii)
    • Fungi (Candida sp., Nocardia sp., Aspergillus sp.)

MD4001 - Disease (7 decks)

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