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Ophthalmology > Microbiology > Flashcards

Microbiology Flashcards

1
Q

Give two examples of gram positive cocci

A

Strep

Staph

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2
Q

Give an example of gram negative

  • Cocci
  • Cocci-bacilli
  • Bacilli
A

Gram negative

  • Cocci – Neisseria
  • Cocci-bacilli – H. influenze
  • Bacilli – pseudomonas
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3
Q

Which pathogens should you suspect in neonatal conjunctivitis?

A 
Most likely from the birth canal, i.e. STIs
- Staph aureus
- Neisseria gonorrhoeae
- Chlamydia trachomatis
Refer all cases to ophthalmology.
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4
Q

Which pathogen should you think of in children with conjunctivitis?

A

H. influenzae

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5
Q

How should you treat bacterial conjunctivitis?

What if theres corneal abrasion?

A

Chloramphenicol eye drops

If corneal abrasion, ointment can be quite soothing

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6
Q

When should you avoid chloramphenicol?

A

History of aplastic anaemia or allergy

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7
Q

What should you consider in a patient with worsening bacterial conjunctivitis despite treatment?

A

Chloramphenicol allergy - may become more itchy as well

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8
Q

What is viral conjunctivitis commonly preceded by?

How does it present?

A

URTI

Very, very red eyes

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9
Q

Which three pathogens should you consider in viral conjunctivitis?

A

Adenovirus
Herpes simplex – looks like small white pustules around the eye
Herpes zoster

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10
Q

Which nerve is affected in herpes zoster of the eye?

A

CN V1 - ophthalmic division of trigeminal nerve

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11
Q

If the tip of the nose is affected by herpes zoster infection, what else is likely to be involved?
Which nerve has been affected?

A

Eye - refer to ophthalmology

Nasociliary nerve

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12
Q

Treatment of herpes zoster infection?

A

Oral acyclovir asap

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13
Q

Chronic history of conjunctivitis which isn’t too bad - which pathogen?
What might be seen on examination?

A

Chlamydia

Exaggerated lymphatic response - looks like rice grains on the inside of the lid

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14
Q

Why does corneal infection need urgent treatment?

A

If you have infection on cornea it can work its way straight through to the back of the eye – very difficult to treat.

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15
Q

What does microbial keratitis look like on examination?

A

Big white lesion on eye – shine cobalt blue on it.
White line along the bottom = white cells within the anterior chamber – inflammatory process is so severe that there is intra-ocular inflammation.

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16
Q

What is a hypopyon and which condition is it associated with?

A

Hypopyon = presence of leukocytes in the anterior chamber of the eye.
Microbial keratitis

17
Q

Investigation of microbial keratitis?

A

Put local anaesthetic eye drops in, take scalpel and scrape surface of eye – send it off for

  • Microscopy
  • Culture
18
Q

Treatment of bacterial keratitis?

A

Admit patient – antibiotic eye drops every hour for 48 hours at least.

19
Q

What does herpes simplex keratitis cause on the cornea?

A

Dendritic type ulcer

This is very painful and can result in reduced corneal sensation

20
Q

What should you not treat viral keratitis with?

A

Steroids - can cause a corneal melt and perforation of the cornea

21
Q

How should viral keratitis be treated?

A

Topical acyclovir 5x per day

22
Q

What can you see on examination of adenoviral keratitis?

A

Subepithelial infiltrates - looks like little white dots on the cornea

23
Q

Treatment of adenoviral keratitis?

A
  • Contagious – tell patient to use different towels from others in the house etc
  • Can give topical AB to prevent secondary infection
  • Patients often have slightly reduced vision
  • Can require steroids to speed up recovery if becomes chronic
24
Q

Give some features of fungal keratitis

A
  • More indolent course than microbial keratitis
  • Usually a history of trauma from vegetation
  • Takes a long time to heal
  • Can get hypopyon
25
Q

Give some clinical features of orbital cellulitis

Which syndrome is a risk and what is the first clinical feature of this?

A
  • Painful – especially on eye movements
  • Proptosis
  • Often associated with paranasal sinusitis
  • Pyrexial
    It is sight threatening and can lead to orbital compartment syndrome. One of the first things to go is colour vision.
26
Q

Investigation of orbital cellulitis?

A

CT scan

27
Q

What is endophthalmitis?

  • What is the most common preceding event?
  • Symptoms?
A

Devastating infection inside of the eye

  • Post surgical
  • Painful +++, with decreasing vision
  • Very red eye
  • Sight threatening
28
Q

What is the most common pathogen in endophthalmitis?

A

Staph epidermis

29
Q

How is endophthalmitis treated?

A

In theatre suck out some of the gel of the eye and inject intravitreal amikacin and vancomycin and topical antibiotics. Send the gel off to the microbiology lab.

30
Q

Which pathogen is associated with endophthalmitis in HIV?

A

Cytomegalovirus

31
Q

Which microbiology infections are done in:

  • Bacterial keratitis
  • Endophthalmitis
  • Acanthomoeba
  • Toxoplasma/toxocara
A
  • Corneal scrapes in bacterial keratitis – only done by microbiologist
  • Aqueous/vitreous for culture in endophthalmitis
  • Microscopy/culture for acanthamoeba – tell patient to bring their contact lens case
  • Serology for toxoplasma and toxocara
32
Q

How does chloamphenicol work?

A
  • Inhibits peptidyl transferase enzyme (therefore stops bacterial protein being made)
  • Bacterocidal for strep and haemophilus
  • Bacterostatic for staph
33
Q

Give three side effects of chloramphenicol

A
  • Allergy
  • Irreversible aplastic anaemia (rare : 1 in 40,000)
  • Grey baby syndrome
34
Q

What is dacrocystitis?

A

Infection of the lacrimal sac, secondary to obstruction of the nasolacrimal duct at the junction of lacrimal sac.

35
Q

Antibiotic for corneal ulcers?

A

Ofloxacin

36
Q

Which bacteria does chloramphenicol not treat?

A

Pseudomonas aeruginosa

37
Q

Which drug is used for staph aureus?

A

Fusidic acid

38
Q

Which pathogens does gentamicin treat?

A

Gentamicin treats most Gram negative bacteria including coliforms, Pseudomonas aeruginosa.

39
Q

How is chlamydial conjunctivitis treated?

A

Topical oxytetracycline

but adults may also need oral azithromycin treatment for genital chlamydia infection

Ophthalmology (9 decks)

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