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Year 2 Microbiology > Ophthalmology Microbiology > Flashcards

Ophthalmology Microbiology 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
Presentation of herpetic keratitis?
Severe pain and less red than expected; can be recurrent and these recurrences eventually cause reduced corneal sensation Examination shows dendritic ulcers (appear branching)
26
Caution with steroid use in herpetic keratitis?
STEROIDS MUST NOT BE ADMINISTERED FOR THIS Virus begins to proliferate and this can cause a corneal melt and perforation of the cornea
27
Presentation of adenoviral keratitis?
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
Examination of adenoviral keratitis?
Small, white sub-epithelial infiltrates can be seen
29
Treatment of adenoviral keratitis?
Can give topical antibiotic to present secondary infection If it becomes chronic, it can require steroids to increase recovery rate
30
Fungal causes of keratitis?
Acanthamoeba (almost always in contact lens wearers) Pseudomonas aeruginosa
31
Presentation of fungal keratitis?
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
What is orbital cellulitis?
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
Presentation of orbital cellulitis?
Periorbital ecchymosis Pain (esp. with eye movement) and proptosis Often assoc. with paranasal sinusitis and they may be pyrexial
34
Complications of orbital cellulitis?
Vision loss
35
Ix for orbital cellulitis?
If there is any suggestion of muscle/optic nerve dysfunction then do a CT scan (to identify orbital abscesses)
36
Organisms causing orbital cellulitis?
* Staphylococci * Streptococci * Coliforms * H. influenzae * Anaerobes
37
What must orbital cellulitis be differentiated from?
From preseptal cellulitis - inflammation and infection of the eyelid and portions of skin around the eye, anterior to the orbital septum
38
Treatment of orbital cellulitis?
Broad-spectrum antibiotics Sometimes, an abscess requires drainage
39
What is endophthalmitis?
Devastating infection of the inside of the eye that is: * Endogenous * Post-surgical (almost always the cause)
40
Presentation of endophthalmitis?
Extreme pain and decreasing vision Very red eye
41
Complications of endophthalmitis?
Visual loss
42
Organisms causing endophthalmitis?
Often conjunctival "commensals" Most common is Staph. epidermidis
43
Treatment of endophthalmitis?
Intravitreal amikacin and vancomycin
44
What is chorioretinitis?
Rare inflammation of the choroid and retina of the eye
45
Organisms causing chorioretinitis?
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
Fundus appearance in haemorrhagic CMV retinitis of AIDs?
Has haemorrhages and ischaemia
47
Presentation of toxoplasmosis?
Mild flu-like illness and rarely causes other issues In immunocompromised patients, it enters a latent phase with cyst formation in the eye
48
Complications of toxoplasmosis?
Can reactivate Sight-threatening
49
Treatment of toxoplasmosis?
Requires systemic treatment, if sight-threatening
50
Presentation of toxocara?
Often self-limiting as no replication Form granulomas, which can cause irreversible visual loss
51
Diagnostic tools for eye infections?
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
3 categories of antibiotics based on action?
* Inhibit protein synthesis * Inhibit cell wall synthesis * Inhibit nucleic acid synthesis
53
Action of chloramphenical?
Inhibits peptidyl transferase enzyme and thus stops bacterial protein production; it is: * Bacterocidal for Strep. and Haemophilus * Bacterostatic for Staph.
54
Side effects of chloramphenical?
Allergy Irreversible aplastic anaemia (rare) Grey baby syndrome
55
Which antibiotics inhibit cell wall synthesis? How?
Penicillins and cephalosporins have a common β-lactam ring, which inhibits the enzyme that makes the cell wall Thus, bacterium dies
56
Which antibiotics inhibit nucleic acid synthesis? How?
Quinolones, e.g: ofloxacin - inhibits DNA gyrase (enzyme that compresses bacterial DNA into supercoils) Leads to unwinding of supercoils and cell death
57
How do bottles remain free of contaminants?
Contain a preservative that prevents contamination for 4 weeks (DO NOT USE BEYOND THIS) Pseudomonas is a common contaminant
58
Mechanism of action of aciclovir?
Inhibits viral DNA synthesis and is a base analogue (mimics guanine)
59
Use of aciclovir in ophthalmology?
Dendritic ulcers of the cornea
60
Types of bacterial conjunctivitis treated by chloramphenicol?
Treats most bacteria except Pseudomonas aeruginosa
61
Types of bacterial conjunctivits treated by fusidic acid?
Treats Staph. aureus
62
Types of bacterial conjunctivitis treated by gentamicin?
Treats most gram -ve bacteria, inc. coliforms, Pseudomonas aeruginosa
63
Types of bacterial keratitis treated by Ofloxacin?
Most gram -ve bacteria inc: * Coliforms * Pseudomonas aeruginosa * H. influenzae NOT active against Strep. pneumoniae
64
Types of bacterial keratitis treated by gentamicin and cefuroxime combination?
Treats most gram +ve and -ve organisms

Year 2 Microbiology (7 decks)

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