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Year 2 Microbiology > Ophthalmology Microbiology > Flashcards

Ophthalmology Microbiology Flashcards

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Biology 101 flashcards
1
Q

Examples of a gram -ve cocci?

A

Neisseria

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2
Q

Example of a gram -ve cocci-bacilli?

A

H. influenzae

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3
Q

Example of a gram -ve bacilli?

A

Pseudomonas

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4
Q

Types of infections that can affect the eye?

A

Conjunctivitis

Keratitis (cornea)

Endophthalmitis (entire globe)

Cellulitis

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5
Q

Causes of a bacterial conjunctivitis in neonates?

A

Staph. aureus

Neisseria gonorrhoea

Chlaymdia trachomatis

Often contracted from the birth canal and may be due to an STI

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6
Q

Necessary action for neonatal cases of bacterial conjunctivitis?

A

REFER all cases to ophthalmology

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7
Q

Causes of bacterial conjunctivitis in other age groups?

A

Staph. aureus

Strep. pneumoniae

H. influenzae (esp. in children)

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8
Q

Presentation of bacterial conjunctivitis?

A

Red

Sticky with mucopurulent discharge

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9
Q

Ix for bacterial conjunctivitis?

A

Swab

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10
Q

Treatment of bacterial conjunctivitis?

A

Topical antibiotic (usually chloramphenical QDS)

There is a choice between drops OR ointment; drops must be storied in the fridge and taken QDS but they are easier to use

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11
Q

Cautions with chloramphenical?

A

Avoid if patient has a Hx of aplastic anaemia or allergy

If their symptoms worsen, consider chloramphenical allergy, esp. if they develop an itch

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12
Q

Causes of viral conjunctivitis?

A

Adenovirus

Herpes simplex

Herpes zoster

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13
Q

Presentation of adenoviral conjunctivits?

A

Profoundly red eye with watery discharge and often there is a Hx of URTI

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14
Q

Presentation of herpes simplex conjunctivitis?

A

Often develop unilateral vesicles below the eye

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15
Q

Presentation of herpes zoster ophthalmicus?

A

Hutchinson’s sign - vesicles on the tip of the nose, or on the side of the nose, that precede development of ophthalmic herpes zoster

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16
Q

Complications of herpes zoster ophthalmicus?

A

Post-herpetic neuralgia - start aciclovir as soon as possible to prevent this

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17
Q

Presentation of chlaymdial conjunctivitis?

A

Often, patient has a chronic Hx of red eye and watery discharge that is not disappearing; they are unresponsive to treatments

Suspicious of this if a young adult has bilateral conjunctivitis

May/may not have symptoms of urethritis or vaginitis

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18
Q

Ix for chlamydial conjunctivitis?

A

Contact tracing

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19
Q

Examination of chlaymdial conjunctivitis shows?

A

FOLLICLES (lymphatic collections) are pathognomonic to this

Subtarsal scarring (of the lower eyelid)

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20
Q

Treatment of Chlamydial conjunctivitis?

A

Topical ocytetracycline

Adults may also need oral azithromycin treatment for genital chlamydia infection

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21
Q

Potential causes of microbial keratitis?

A

Bacteria Viruses:

  • Herpes
  • Adenovirus
  • Fungus
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22
Q

Examination of bacterial keratitis?

A

May show a hypopyon (inflammatory cells in the anterior chamber of the eye cause a yellow-white area in the iris); they are present in a corneal ulcer

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23
Q

Treatment of bacterial keratitis?

A

Under LA, scrapings of the eye can be taken for microscopy

Require admission to hospital for HOURLY DROPS and a daily review over a period of 48 hours; the patient is woken up at night to do this as well

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24
Q

Issues assoc. with bacterial keratitis?

A

Normal corneas do not get infected so there is usually:

  • Another corneal pathology
  • Contact lens wearing patient
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25
Q

Presentation of herpetic keratitis?

A

Severe pain and less red than expected; can be recurrent and these recurrences eventually cause reduced corneal sensation

Examination shows dendritic ulcers (appear branching)

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26
Q

Caution with steroid use in herpetic keratitis?

A

STEROIDS MUST NOT BE ADMINISTERED FOR THIS

Virus begins to proliferate and this can cause a corneal melt and perforation of the cornea

27
Q

Presentation of adenoviral keratitis?

A

Tends to occur following a URTI BILATERAL and contagious

May affect vision (blurred)

It is very contagious so advise use of own towels, etc

28
Q

Examination of adenoviral keratitis?

A

Small, white sub-epithelial infiltrates can be seen

29
Q

Treatment of adenoviral keratitis?

A

Can give topical antibiotic to present secondary infection

If it becomes chronic, it can require steroids to increase recovery rate

30
Q

Fungal causes of keratitis?

A

Acanthamoeba (almost always in contact lens wearers)

Pseudomonas aeruginosa

31
Q

Presentation of fungal keratitis?

A

More indolent course than microbial keratitis

Patient usually has a Hx of trauma from vegetation

May have a hypopyon Long healing and treatment period

32
Q

What is orbital cellulitis?

A

Inflammation of the eye behind the orbital septum

Often due to:

  • Direct extension from sinuses, e.g: rhinosinusitis
  • Extension from focal orbital infection, e.g: infected chalazion and dacrocystitis)
  • Post-operative
33
Q

Presentation of orbital cellulitis?

A

Periorbital ecchymosis

Pain (esp. with eye movement) and proptosis

Often assoc. with paranasal sinusitis and they may be pyrexial

34
Q

Complications of orbital cellulitis?

A

Vision loss

35
Q

Ix for orbital cellulitis?

A

If there is any suggestion of muscle/optic nerve dysfunction then do a CT scan (to identify orbital abscesses)

36
Q

Organisms causing orbital cellulitis?

A
  • Staphylococci
  • Streptococci
  • Coliforms
  • H. influenzae
  • Anaerobes
37
Q

What must orbital cellulitis be differentiated from?

A

From preseptal cellulitis - inflammation and infection of the eyelid and portions of skin around the eye, anterior to the orbital septum

38
Q

Treatment of orbital cellulitis?

A

Broad-spectrum antibiotics

Sometimes, an abscess requires drainage

39
Q

What is endophthalmitis?

A

Devastating infection of the inside of the eye that is:

  • Endogenous
  • Post-surgical (almost always the cause)
40
Q

Presentation of endophthalmitis?

A

Extreme pain and decreasing vision

Very red eye

41
Q

Complications of endophthalmitis?

A

Visual loss

42
Q

Organisms causing endophthalmitis?

A

Often conjunctival “commensals”

Most common is Staph. epidermidis

43
Q

Treatment of endophthalmitis?

A

Intravitreal amikacin and vancomycin

44
Q

What is chorioretinitis?

A

Rare inflammation of the choroid and retina of the eye

45
Q

Organisms causing chorioretinitis?

A

CMV in AIDS

Toxoplasma gondii (protozoan infection)

Toxocara canis (parasitis nemotode - roundworm); it affects cats/dogs and is unable to replicate in humans so it remains in its immature worm form

46
Q

Fundus appearance in haemorrhagic CMV retinitis of AIDs?

A

Has haemorrhages and ischaemia

47
Q

Presentation of toxoplasmosis?

A

Mild flu-like illness and rarely causes other issues

In immunocompromised patients, it enters a latent phase with cyst formation in the eye

48
Q

Complications of toxoplasmosis?

A

Can reactivate

Sight-threatening

49
Q

Treatment of toxoplasmosis?

A

Requires systemic treatment, if sight-threatening

50
Q

Presentation of toxocara?

A

Often self-limiting as no replication

Form granulomas, which can cause irreversible visual loss

51
Q

Diagnostic tools for eye infections?

A

Bacterial, Chlamydial, viral - swabs for culture; consent must be gained for Chlaymdial swabs

Bacterial keratitis - corneal scrapes

Endophthalmitis - aqueous/vitreous for culture

Acanthamoeba - microscopy/culture

Toxoplasma and toxocara - serology

52
Q

3 categories of antibiotics based on action?

A
  • Inhibit protein synthesis
  • Inhibit cell wall synthesis
  • Inhibit nucleic acid synthesis
53
Q

Action of chloramphenical?

A

Inhibits peptidyl transferase enzyme and thus stops bacterial protein production; it is:

  • Bacterocidal for Strep. and Haemophilus
  • Bacterostatic for Staph.
54
Q

Side effects of chloramphenical?

A

Allergy

Irreversible aplastic anaemia (rare)

Grey baby syndrome

55
Q

Which antibiotics inhibit cell wall synthesis? How?

A

Penicillins and cephalosporins have a common β-lactam ring, which inhibits the enzyme that makes the cell wall

Thus, bacterium dies

56
Q

Which antibiotics inhibit nucleic acid synthesis? How?

A

Quinolones, e.g: ofloxacin - inhibits DNA gyrase (enzyme that compresses bacterial DNA into supercoils)

Leads to unwinding of supercoils and cell death

57
Q

How do bottles remain free of contaminants?

A

Contain a preservative that prevents contamination for 4 weeks (DO NOT USE BEYOND THIS)

Pseudomonas is a common contaminant

58
Q

Mechanism of action of aciclovir?

A

Inhibits viral DNA synthesis and is a base analogue (mimics guanine)

59
Q

Use of aciclovir in ophthalmology?

A

Dendritic ulcers of the cornea

60
Q

Types of bacterial conjunctivitis treated by chloramphenicol?

A

Treats most bacteria except Pseudomonas aeruginosa

61
Q

Types of bacterial conjunctivits treated by fusidic acid?

A

Treats Staph. aureus

62
Q

Types of bacterial conjunctivitis treated by gentamicin?

A

Treats most gram -ve bacteria, inc. coliforms, Pseudomonas aeruginosa

63
Q

Types of bacterial keratitis treated by Ofloxacin?

A

Most gram -ve bacteria inc:

  • Coliforms
  • Pseudomonas aeruginosa
  • H. influenzae

NOT active against Strep. pneumoniae

64
Q

Types of bacterial keratitis treated by gentamicin and cefuroxime combination?

A

Treats most gram +ve and -ve organisms

Year 2 Microbiology (7 decks)

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