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Biomed > Tasos CNS and Eye infections > Flashcards

Tasos CNS and Eye infections Flashcards

1
Q

What does the CNS consist of?

A

Brain and spinal cord

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2
Q

What are the meninges?

A 
Protective membranes of CNS
Dura mater (2 layers)
- outermost membranes
Arachnoid membrane
- middle layer
Pia mater
- Inner membrance closest to brain and spinal cord
Between pia mater and arachnoid membrane in subarachnoid space filled with CSF
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3
Q

What are the 2 forms of meningitis?

A

Acute and chronic

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4
Q

Next questions concerned with acute meningitis

A

okay sir

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5
Q

How does viral meningitis compare with bacterial?

A

Viral meningitis more common than bacterial but generally less serious

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6
Q

How is viral meningitis spread and what is its incubation period?

A

Spread between people by coughing or sneezing, through poor hygiene or in sewage polluted water
- Incubation period can be up to 3 weeks

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7
Q

What are the symptoms of viral meningitis?

A

Similar to bacterial form but severe meningitis will result in hospital admittance
- Diarrhea can occur with mild viral meningitis

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8
Q

What virus is the most common cause of viral hepititis?

A

Coxsackie

  • found in intestines of humans, therefore present in faeces and sewage polluted water
  • Most cases occur in summer months
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9
Q

What are common signs and symptoms of bacterial meningitis?

A 
- In persons over 2
Main symptoms:
> high fever
> stiff neck
> headache
Other symptoms include:
> nausea
> vomiting
> photophobia
> confusion
In newborns and infants
High fever, stiff neck and headaches may be hard to detect
Other signs are:
> inactivity
> Irritability
> Vomiting
> Poor feeding

Patients of any age can have seizures

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10
Q

What is the cause of bacterial meningitis and what are the common infective agents?

A
  • Serious infection of the CNS around the brain and SC and meninges
  • Common agents:
    > Haemophilus influenzae (Pitmans type B strain)
    > Neisseria meningitidis
    > Streptococcus pneumoniae
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11
Q

How is bacterial meningitis spread and how is it treated?

A

Spread from person to person by contact with discharges from nose or throat of infected individual
- Treated with antibiotics

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12
Q

What age of people is Haemophilus influenzae type B (Hib) meningitis found in?

A

Infants

- very rare after age of 4

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13
Q

What is the structure of Haemophilus species and where are they normally found?

A

Small Gram Negative Rods

Component of normal throat flora and is often associated with lower respiratory tract infections

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14
Q

How is Hib tested for?

A

Satellite phenomenon test

  • Hib will only grow in presence of Haematin and NAD
  • This phenomenon is known as satellitism
  • Hib gets its haematin from blood agar and NAD from Staphylococcus streaked across the culture
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15
Q

What is Neisseria meningitidis?

A
  • One of the most common causes of meningitis worldwide

- Intracellular gram negative coccus - often in pairs

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16
Q

What 2 diseases can Neisseria meningitidis cause and which is most severe?

A

Meningitis - inflammation of meninges
Septicaemia - blood poisoning form of the disease
Both can kill in hours
Septicaemic form most severe

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17
Q

Where is Neisseria meningitidis common and when do outbreaks usually occur?

A
  • Common in sub Saharan Africa (called the meningitis belt)
  • Outbreaks occur mainly when groups from different areas get together for first time and share their microbial flora i.e first week of uni
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18
Q

What are the symptoms of Neisseria meningitidis?

A
  • Pinpoint red spots
  • High fever
  • Headches
  • Severe malaise (feeling very unwell)
  • Nausea and vomiting
  • Stiff neck
  • Photophobia
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19
Q

What causes red spots and rashes in Neisseria meningitidis patients?

A

Caused by bleeding from bloodstream pooling under the skin

- Bleeding occurs when blood vessels are damaged by the release of endotoxin in large amounts

20
Q

What is another effect of blood leaking in Neisseria meningitidis?

A

Blood pressure falls dramatically

  • reduces circulation to extremities
  • In some cases gangrene will occur
21
Q

What is used in prevention of Neisseria meningitidis?

A

Meningococcal vaccine available against four most common strains (A, C, Y, W-135)

  • can be used in humans older than 2
  • 85-100% effective in treating A and C
  • No vaccine against type B strain
22
Q

What is Naegleria fowleri and what does it cause?

A
  • Unicellular parasite
  • Ability to transform from an amoeba to a flagellate to a cyst form
  • Causes primary amoebic meningoencephalitis
23
Q

What is chronic meningitis?

A

Forms of meningitis where organisms invade the meninges and fluid surrounding the brain or there is damage to the skull and organisms leak in

  • Develops over weeks (acute strikes suddenly)
  • Rare
  • Symptoms similar to acute
24
Q

How do brain abscesses cause meningitis?

A
  • Bacteria or fungi infect brain causing inflammatory reponse
  • Infected brain cells, white blood cells and microorganisms collect in limited area
  • This is enclosed by membrane that forms around to create a mass
  • Imflammation causes swelling, which puts pressure on delicate brain tissue, causing damage
  • Mass can cause blockage of blood vessels causing hypoxia and further damage
25
Q

What are the eyelids and how are they useful in pathogen protection?

A
  • Upper and lower eyelids are folds of skin that can cover the eye
  • Blink to form mechanical barrier from light, wind, dust and foreign objects (very quick reflex)
  • Eyelids help to spread moisture (tears) over surface of eye
26
Q

How are tears produced and why are they important?

A
  • Tear fluid formed in the tear gland and then transported via number of ducts to eye surface
  • Fluid is drained through the tear canal into the lacrimal sac, which then is connected with nose
  • Tear film important for moisture and to wash away particles
  • Film mostly composed of tear fluid i.e salt and water and other things
27
Q

What is the main constituents of tear fluid?

A 
Tear fluid contains:
- Water
- lipids
- lysosome
- Igs
- glucose
- Urea
- Sodium
- Potassium
Some of these substances fight against bacterial infection
28
Q

Why is the conjunctiva susceptible to infection?

A

Epithelial outer surface of eye - exposued to environment

Covered by eyelids - creates a warm, moist, enclosed environment in which organism can establish infection

29
Q

What is conjunctivitis?

A
  • Referred to as pink eye
  • Inflammation of the conjunctiva (membrane that covers the sclera)
  • Common
30
Q

What are the 3 main types of conjunctivitis?

A

1) Infective
2) Allergic
3) Irritant (shampoo, chlorinated water etc)

31
Q

What are the symptoms of conjunctivitis?

A
  • Redness of eye
  • Watering of eye
  • Yellow sticky coating on eyelashes
  • Itchiness
32
Q

What are the most common organisms that causes infective conjunctivitis?

A
  • Staphylococcus aureus
  • haemophilus influenzae
  • Streptococcus pneumoniae
  • Pseudomonas aeruginosa
33
Q

What are the main modes of conjunctivitis transmission?

A
  • Discharge from the conjunctivae or upper respiratory tract of infected persons (e.g droplets from coughing and sneezing): Primary transmittance
  • Contaminated objects
  • Infected mothers during vaginal delivery
34
Q

What occurs in Ophthalmia neonatorum (neonatal jaundice)?

A
  • Contracted during delivery by an infant whose mother is infected with gonorrhoea or chlamydia
  • Can cause blindness if not promptly treated
  • Usually appears 1 to 2 days post delivery
35
Q

What is keratitis?

A

Inflammation or irritation of the cornea

  • Characterised by cloudiness
  • Infections generally occur after the cornea has been injured, allowing bacteria to enter
  • Deeper the infection, more severe its symptoms and complications
36
Q

What causes keratitis?

A

Bacterial infections

  • Improper care or cleaning of contacts
  • contaminated eye make up (usually aggressive infections, characterised by waking up with eyelids stuck together)
37
Q

What is Acanthamoeba and what does it cause?

A

Acanthamoeba is a free-living amoeba
Found in bodies of water, soil and air
- Causes Acanthamoeba keratitis

38
Q

What is Acanthamoeba keratitis and what are the symptoms?

A
  • Infection of the cornea
  • Can cause permanent visual impairment or blindness
    Symptoms:
    > Pain
    > Redness
    > Blurred vision
    > Photophobia
    > Excessive tearing
39
Q

What are some risks of infection of Acanthamoeba keratitis?

A
  • Storing and handling lenses improperly
    > Disinfecting lenses improperly
    > Swimming, showering while wearing contacts
    > Contact with contaminated water
    > History of cornea trauma
40
Q

What is Endophthalmitis? What is the most common type?

A
  • Intraocular infection
  • Most common type is post-operative endophthalmitis
  • This condition is common after cataract surgery (1 in every 1000 patients)
  • Around 3 to 12 days post op
41
Q

Next questions concern periocular diseases (around the eye)

A

lets go

42
Q

What is Blepharitis?

A

Refers to chronic inflammation of the eyelids

- Symptoms are normal eye conditions symptoms (redness, tearing, itching, photophobia etc) plus sandy, gritty sensation

43
Q

What are the 3 forms of blepharitis?

A

1) Staphylococcal
2) Seborrheic
3) Meibomian gland dysfunction (MGD)

44
Q

What occurs in Staphylococcal Blepharitis?

A
  • Edge of eye becomes inflamed

- Ulcers may form because of secondary infection

45
Q

What occurs in Seborrheic blepharitis?

A
  • Redness of the lids
  • Scales and flaking of eyelashes
  • Often associated with dandruff of scalp
46
Q

What occurs in Meibomian gland dysfunction blepharitis?

A
  • Produces lipid like secretions that coat the tear layer to prevent evaporation
  • Defects cause tears to evaporate more quickly
  • —> dryness
  • Gland dysfunction due to clogging of oil
47
Q

What is Canaliculitis?

A

Imflammation of the canaliculus

- Occurs in adults and causes a secondary conjunctivitis

Biomed (18 decks)

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