Microbiology of Opthamology Flashcards

1
Q

What is the term given to describe inflammation of the cornea?

A

Keratitis

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2
Q

What is the term to desribe entire globe inflammation?

A

Endophthalmitis

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3
Q

What are the main causes of bacterial conjunctivitis in neonates?

A
  1. S. aureus
  2. Neisseria gonorrhoea
  3. Chlamydia trachomatis
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4
Q

What are the main causes of bacterial conjunctivitis outwith the neonatal period and in the rest of life?

A
  1. S. aureus
  2. Streptococcus pneumonia
  3. Haemophilus influenzae
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5
Q

How is bacterial conjunctivitis normally treated?

A

Chloramphenical (topical antibiotic)

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6
Q

What are the two main reasons chloramphenicol may be avoided?

A
  1. History of aplastic anaemia
  2. Allergy
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7
Q

What is aplastic anaemia?

A

Disease causing damage to haematopoietic stem cells in marrow

There is deficiency of red cells, white cells and platelets

There is inability of the stem cells to generate mature blood cells

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8
Q

What are the main causes of viral conjunctivitis?

A
  1. Adenovirus
  2. Herpes simplex
  3. Herpes zoster
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9
Q

Why may antibiotics be prescribed in viral conjunctivitis?

A

Prevent secondary infection

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10
Q

Herpes zoster opthalmicus is a type of which disease?

A

Shingles

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11
Q

How can herpes zoster opthalmicus be identified clinically?

A
  1. Hutchison’s sign (involvement of tip, side, or root of the nose)
  2. Red eyes
  3. Crusting lesions in CN V dermatome
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12
Q

How should herpes zoster opthalmicus be treated?

A

Antivirals within 72 hours

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13
Q

Subsequent to having herpes zoster opthalmicus, patients often suffer from what?

A

Post herpetic neuralgia

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14
Q

Chlamydial conjunctivitis is often associated with which type of history?

A
  1. Chronic
  2. Unresponsive to previous treatments
  3. Bilateral conuunctivitis in the young
  4. Symptoms of urethritis or vaginitis
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15
Q

The inner eyelid in chlamydial conjunctivitis has what distinctive appearance?

A

Follicular “rice grain” conjunctivitis

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16
Q

Keratitis may be induced by which microbe types?

A
  1. Bacteria
  2. Viruses
  3. Fungi
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17
Q

Which type of history is associated with a bacterial keratitis?

A
  1. Short
  2. Painful
  3. Hypopyon in cornea
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18
Q

Which clinical sign is almost pathognomonic of bacterial keratitis?

A

Hypopyon

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19
Q

What is the treatment plan for someone with bacterial keratitis?

A
  1. Hospital admission
  2. Eyedrops every hour
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20
Q

Bacterial keratitis is usually seen in association with which other factors?

A
  1. Other corneal pathologies
  2. Contact lens wear
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21
Q

Which type of virus will normally induce keratitis?

A
  1. Herpes
  2. Adenovirus
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22
Q

Herpetic keratitis is associated with which almost pathognomonic clinical sign?

A

Dendritic ulcer

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23
Q

Herpetic keratitis is very painful

True or false?

A

True

Patients may not be able to open their eyes for examination

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24
Q

What often happens with herpetic keratitis recurrences?

A

Corneal sensation is reduced with each recurrence

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25
Why must steroids be used extremely carefully when treating herpetic keratitis?
They may induce a corneal melt and perforation
26
Adenoviral keratites are associated with which clinical sign?
Subepithelial infiltrates
27
Adenoviral keratitis will usually come on following what?
1. URTI 2. Adenoviral conjunctivitis
28
Usually adenoviral keratitis is self-limiting, but when chronic, which treatment may be given?
Low dose steroids
29
Which bacteria can induce keratitis?
Pseudomonas aeruginosa
30
Which type of history is classical for fungal keratitis?
1. Chronic non-severe history 2. Farm worker who gets something in eye
31
Fungal keratitis may be associated with which clinical sign?
Hypopyon | (much rarer than bacterial keratitis)
32
Which clinical signs are most notable for orbital cellulitis?
1. Pain on eye movements 2. Proptosis 3. Paranasal sinusitis 4. Sight threatening
33
Orbital cellulitis often results from where?
Nasal compartments e.g. paranasal sinusitis (post operation and insect bites rarely induce)
34
In a patient with orbital cellulitis, what is the first thing they might notice?
Red vision disappears
35
Which extra-ocular muscle will often fail during orbital cellulitis?
Medial rectus (patients need to turn their head rather than move their eyes)
36
Which organisms often cause orbital cellulitis?
1. Staphylococci 2. Streptococci 3. Coliforms 4. Haemophilus influenzae 5. Anaerobes
37
Muscle or optic nerve dysfunction warrants what in orbital cellulitis?
CT scan
38
What are the main treatment options for orbital cellultitis?
1. Broad spectrum antibiotic 2. Abscess drainage (if severe)
39
Endophthalmitis is relatively mild True or false?
False This can be devastating and result in **loss of vision**
40
How ca endophthalmitis be induced?
1. Post-surgical 2. Endogenous
41
What is the classical history for endophthalmitis?
1. Extreme pain 2. Decreasing vision 3. **Very short history** 4. Very red eye
42
Which microbes will often induce endophthalmitis
Conjunctival commensals Staph epidermidis is the most common
43
How should endophthalmitis be treated?
1. Intravitreal amikacin/ceftazidime/vancomycin and topical antibiotics 2. Systemic antibiotics (4th gen quinolones work fastest) 3. Pars Plana Vitrectomy (removal of vireous fluid from eye) 4. Corticosteroids (controversial, but may be required to minimise damage from inflammatory response)
44
What are the main causes of chorioetinitis?
1. CMV in AIDS 2. Toxoplasma gondii 3. Toxocara canis
45
What is the characteristic sign of haemorrhagic CMV retinitis in AIDS?
Pizza pie fundus
46
Toxoplasmosis is which type of infection?
Protozoan
47
Toxoplasmosis gondii infection often comes from whcih sources?
1. Cats 2. Raw meat
48
Toxoplasmosis gondii infection often causes what in patients?
1. Mild flu-like illness 2. Cysts may form in the eye (can be sight threatenign)
49
What is Toxocara canis?
Nematode
50
Where can Toxocara canis infection commonly be obtained?
1. Cats 2. Dogs
51
Toxocara canis can cause what which may result in sight loss?
Granulomas (however it is often a self limiting condition as larvae cannot replicate in humans)
52
How are different eye conditions diagnosed?
1. Swabs - Bacterial, viral 2. Corneal scrapes - Bacterial keratitis 3. Aqueous/vitreous culture - endophthalmitis 4. Microscopy/culture - Acanthamoeba 5. Serology - Toxoplasma and Toxocara
53
What are the three main ways in which antibiotics can function?
1. Inhibit protein synthesis 2. Inhibit cell wall synthesis 3. Inhibit nucleic acid synthesis
54
How does chloramphenicol work?
Inhibits peptidyl transferase enzyme | (prevents protein production)
55
Chloramphenicol can causes which syndrome in infants?
Grey baby syndrome (caused by accumulation of chloramphenicol due to **abscence of liver enzymes** to break it down, and **lack of renal excretion**)
56
What is dacrocystitis?
Infection of lacrimal sac as a result of a blocked nasolacrimal duct
57
When should ofloxacin be used?
Only in bacterial keratitis
58
How do quinolones function?
Inhibition of DNA gyrase | (unwinding DNA and cell death)
59
What is the issue with keeping eye bottles long term?
After around 4 weeks they will become contaminated (usually with pseudomonas) This will cause infection (bacterial conjunctivitis) if used
60
Chloramphenical will not treat which bacteria associated with which bacteria?
Pseudomonas aeruginosa
61
Which treatment is ideal for S. aureus bacterial conjunctivitis?
Fusidic acid
62
What will gentamicin treat?
Most gram negative bacteria | (including Pseudomonas aeruginosa)
63
Dendritic ulcers of the cornea are treated with what?
Antivirals e.g. aciclovir **NO** steroid drops
64
Which treatment is required for chlamydial conjunctivitis?
1. Topical oxytetracycline 2. Oral azithromycin may also be required in adults for genital manifestations
65
In terms of treating bacterial keratitis, 4th generation quinolones e.g. ofloxacin are not active against which bacteria?
Strep. pneumoniae
66
The combination of which two antibiotics will treat most gram positive and negative organisms in bacterial keratitis?
Gentamicin and cefuroxime
67
Keratitis can be caused by which protozoa most commonly?
Acanthamoeba