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Ophthalmology > week 1 microbiology > Flashcards

week 1 microbiology Flashcards

1
Q

name a gram +ive cocci

A

strep, staph

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2
Q

what is keratitis

A

inflammation of cornea

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3
Q

name a gram -ive cocci

A

neisseria

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4
Q

name a gram -ive cocci-bacilli

A

h.influenzae

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5
Q

name a gram -ive bacilli

A

psuedomonas

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6
Q

what is endophthalmitis

A

entire globe inflammation

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7
Q

infection of skin round eye

A

infection/inflammation of the eye skin

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8
Q

what can conjunctivitis be cause by

A

viral and bacterial

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9
Q

how to tell difference between bacterial and viral conjunctivitis?

A 
bacterial = pus (lots)
viral = watery
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10
Q

common infective organisms in bacterial conjunctivitis in newborn/baby

A

Staph aureus
Neisseria gonorrhoeae
Chlamydia trachomatis

(refer all cases to ophthalmology)

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11
Q

common infective organisms in bacterial conjunctivitis in adult

A

Staph aureus
Strep pneumoniae
Haemophilus influenzae (especially in children)

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12
Q

treatment for bacterial conjunctivitis

A

Swab

Topical antibiotic usually chloramphenical qds, (drops vs ointment)

if not responding then culture will give answer

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13
Q

what is difference between drops and ointment for chloramphenicol

A 
drops = easy, need stored in fridge
ointment = causes blurry vision
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14
Q

contraindications of using chloramphenicol

A

history of aplastic anaemia or allergy(worsening symptoms = allergy)

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15
Q

what are the main organisms causing viral conjunctivitis

A

Adenovirus
Herpes simplex
Herpes zoster

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16
Q

treating viral conjunctivitis

A

swab not usually necessary (can PCR if necessary).

sometimes antibiotics given to prevent secondary infection

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17
Q

herpes zoster ophthalmicus symptoms

A
  • hutchinsons sign (nasocilary nerve), could have eye involvement.
  • prolonged post-disease neuralgia
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18
Q

what are the 4 CN with parasympathetic function

A

3, 7, 9, 10

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19
Q

treatment for herpes zoster ophthalmicus

A

antivirus within 72hrs

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20
Q

chlamydial conjunctivits PC

A

young adult, bilateral chronic Hx of being unresponsive to treatments. vaginits or urethritis may be present

“rice grains” = follicles
subtarsal scarring can occur

chlamydia infections need contact tracing /phone number.

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21
Q

causes of keratitis

A

Bacteria
Viruses
Fungi

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22
Q

how can you differential bacterial/fungal keratitis from viral

A

hypopyon (sight threatening disease)

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23
Q

treatment for Bacterial keratitis

A

Need admission for hourly drops
Daily review
can perforate=bad

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24
Q

risk factors for bacterial keratitis

A

[Usually in association with other corneal pathology or contact lens wear]

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25
Q

what are the causative organisms of viral keratitis

A

herpes, adenovirus

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26
Q

what is a common finding with Herpetic keratitis

A

dendritic ulcer

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27
Q

PC of bacterial keratitis

A

painful red eye, short Hx, reduced vision

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28
Q

PC of herpetic keratitis

A

very painful to open eyes, may need local anaesthetic (topical). recurrence can occur with patient noticing reduced vision and less pain (reduced corneal sensation).

29
Q

what should never be given to patient with PMHx of herpetic keratitis. why?

A

steroids - causes corneal melt and perforated cornea. develop geographical ulcer

30
Q

what is seen in adenovirus keratitis?

A

superepithlial infiltrates

31
Q

PC of adenoviral keratitis

A

Bilateral
Usually follows an URTI
Contagious
may affect vision

32
Q

treatment of adenoviral keratitis

A

Can give topical AB to prevent secondary infection

Can require steroids to speed up recovery if becomes chronic

33
Q

keratitis use by contact lenses (organisms)?

A

Acanthamoeba

Pseudomonas aeruginosa

34
Q

PC fungal keratitis

A

less aggressive than microbial keratitis

Usually a history of trauma from vegetation - farmer.

healing takes a long time

35
Q

orbital cellulitis PC

A 
painful (esp on eye movements)
Proptosis
Often associated with paranasal sinusitis (although can be insect bite on eyelid traveling backwards)
Pyrexial
Sight threatening
36
Q

investigation of orbital cellulitis

A

Cared for by ENT and Ophthalmology(admit)

CT scan to identify orbital abscesses

37
Q

how to distinguish between between preseptal and orbital cellulitis

A

examination. vision (loss of red colour) and painful rectus medial on moving eye. also skin is well marked around orbit in orbital

38
Q

causative organisms of orbital cellulitis

A 
Staphylococci
Streptococci
Coliforms
Haemophilus influenzae
anaerobes
39
Q

orbital cellulitus treatment

A

If any suggestion there is restriction of muscles or optic nerve dysfunction then scan (CT)
Broad spectrum AB and monitor closely
Sometimes an abscess will require drainage

40
Q

what is endopthalmitis? why does it occur?

A

Devastating infection inside of the eye

Post-surgical or endogenous

41
Q

PC of Endophthalmitis

A

Painful +++, with decreasing vision
Very red eye
[Sight threatening]

42
Q

most common organism causing Endophthalmitis?

A

Often conjunctival “commensals”

Most common is staph epidermidis

43
Q

treatment of Endophthalmitis?

A

Intravitreal(inject eye) amikacin/ ceftazidime/ vancomycin and topical antibiotics

systemic antibiotics too (but due to poor vascular supply not too useful; usually bugs, IS, ABs don’t get to that part of eye - so infection v destructive)

44
Q

what is Chorioretinitis

A

inflammation of back of the eye/retina

45
Q

causes of Chorioretinitis

A

CMV in AIDS - Haemorrhagic CMV retinitis
Toxoplasma gondii
Toxocara canis (worm)

46
Q

what is the pizza-pie sign seen in?

A

Haemorrhagic CMV retinitis in AIDS - not issue due to good HIV treatment

47
Q

what causes toxoplasmosis? what type of infection is this?

A

Toxoplasma gondii

protozoal infection

48
Q

key facts about toxoplasmosis (Chorioretinitis)

A

Protozoan infection by toxoplasmosis gondii
Cats and raw meat
Mild flu like illness
Rarely causes any further problems
In immunocompetent patients it enters latent phase with cysts forming
Very common- 10% of USA sample had toxoplasmosis specific IgG

49
Q

treatment of toxoplasmosis Chorioretinitis

A

only causes problem if macula gets scarred; requires systemic treatment if life-threatening

50
Q

toxocara canis (worms) keys facts

A

Parasitic nemotode (roundworm)
Affects cats or dogs
Unable to replicate in humans
Remains an immature form of the worm (larvae)
Often self limiting as they cannot replicate
Form granulomas which can cause irreversible visual loss

51
Q

how to diagnose bacterial keratitis

A

corneal scrapes

52
Q

how to diagnose endophthalmitis

A

Aqueous/vitreous for culture

53
Q

how to diagnose acanthamoeba in eye

A

microscopy/culture

54
Q

how to diagnose toxoplasma or toxicara in eye

A

serology

55
Q

how to diagnose bacterial, viral, chlamydial infection in eye?

A

Swabs for culture

56
Q

what is the most commonly used topical antibiotic for the eyes?

A

Chloramphenicol

57
Q

how does Chloramphenicol work?

A

-Inhibits peptidyl transferase enzyme (therefore stops bacterial protein being made)

  • Bacterocidal for strep and haemophilus
  • Bacterostatic for staph
58
Q

side effects of Chloramphenicol

A

Allergy
Irreversible aplastic anaemia (rare : 1 in 40,000)
Grey baby syndrome (build up of Chloramphenicol )

59
Q

what antibiotics inhibit cell wall synthesis?

A

Penicillins & cephalosporins have common B lactam ring
B lactam ring inhibits enzyme which makes bacterial cell wall
[Without cell wall, bacteria die]

60
Q

what is Dacryocystitis?

A

Dacryocystitis is an infection of the lacrimal sac, (secondary to obstruction of the nasolacrimal duct at the junction of lacrimal sac)

61
Q

what antibiotics inhibit nucleic acid synthesis?

A

Quinolones e.g. ofloxacin, inhibit DNA gyrase, an enzyme that compresses bacterial DNA into supercoils

[Inhibition of DNA gyrase leads to unwinding of supercoils and cell death]

62
Q

when is only case ofloxacin should be used? why?

A

bacterial keratitis.

to prevent resistance

63
Q

eye drop bottles don’t keep loner than a month even in fridge(4 weeks) - what is the commonest contaminant

A

Pseudomonas

64
Q

how to treat bacterial conjunctivitis?

A

chloramphenicol
(treats most bacteria except Pseudomonas aeruginosa)
fusidic acid
(treats Staph. aureus)
gentamicin
(treats most Gram negative bacteria including coliforms, Pseudomonas aeruginosa)

65
Q

what is acyclovir. how is it given? why is it used?

A

anti-viral, topical/systemic.

used for detritus ulcer in cornea to stop preforation

66
Q

how does acyclovir work ?

A 
Aciclovir inhibits viral DNA synthesis
Base analogue (mimics guanine)
67
Q

what should not be given to patient with red eye? when can it be?

A

steroids

can be once slit lamp shows no dendritic ulcer

68
Q

how to treat Chlamydial conjunctivitis

A

topical oxytetracycline

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

69
Q

how to treat bacterial keratitis?

A

A 4-quinolone (Ofloxacin)
(treats most Gram negative bacteria including coliforms, Pseudomonas aeruginosa, Haemophilus influenzae. Not active vs. Strep. pneumoniae)

Gentamicin and cefuroxime
(the combination will treat most Gram positive and Gram negative organisms but is more toxic to eye itself)

Ophthalmology (17 decks)

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