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Opthamology > Microbiology in Opthamology > Flashcards

Microbiology in Opthamology Flashcards

1
Q

what are the 3 causes of bacterial conjunctivitis in neonates?

A

staph aureus
Neisseria gonorrhoea
chlamydia trachomatis
all cases in neonates must be referred to ophthalmology

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2
Q

3 causes of bacterial conjunctivitis in other ages?

A

staph aureus
strep pneumoniae
haemophilus influenzae (esp in children)

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3
Q

how is bacteria conjunctivitis managed?

A 
swab
topical antibiotic (usually chloramphenicol)
drops vs ointment
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4
Q

when must chloramphenicol be avoided?

A

if history of aplastic anaemia or allergy

be aware that allergy may be present if symptoms worsen

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5
Q

3 causes of viral conjunctivitis?

A

adenovirus
herpes simplex
herpes zoster

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6
Q

what may indicate a chlamydial conjunctivitis?

A

chronic history
unresponsive to treatments
suspect in bilateral conjunctivitis in young adults
may or may not have symptoms of urethritis or vaginitis
need contact tracing

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7
Q

what may chlamydial conjunctivitis look like?

A

follicles like tiny grains of rice in the conjunctiva

can cause tubtarsal scarring

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8
Q

3 causes of microbial keratitis?

A

bacteria
viruses
fungi

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9
Q

what does bacterial keratitis look like?

A

level of white within the cornea due to mixing up of precisely arranged collagen fibres as a result of swelling, inflammation etc

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10
Q

what is a hypopyon?

A

a leukocytic exudate, seen in the anterior chamber, usually accompanied by redness of the conjunctiva and the underlying episclera

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11
Q

how is bacterial keratitis managed?

A

need admission for hourly drops
daily review
usually in association with other corneal pathology or contact lens wearer

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12
Q

name 2 causes of viral keratitis?

A

herpes

adenovirus

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13
Q

bacterial vs viral keratitis?

A 
bacterial = usually have an underlying pathology associated
viral = can just happen in otherwise healthy eyes
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14
Q

how might herpetic keratitis present?

A

dendritic ulcer
shows under blue light
incredibly painful (especially the first time)
can be recurrent which can eventually result in reduced corneal sensation

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15
Q

how is herpetic keratitis managed?

A

NEVER GIVE STEROIDS
- can cause a corneal melt and perforation
??? (flurosine?)

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16
Q

how might adenoviral keratitis present?

A 
subepithelial infiltrates
bilateral
usually after URTI
may affect vision
contagious
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17
Q

how is adenoviral keratitis managed?

A

can give topical AB to prevent secondary infection

can require steroids to speed up recovery if it becomes chronic

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18
Q

what is acanthamoeba?

A

type of fungal keratitis
- pseudomonas aeruginosa
usually occurs in contact lens wearer
more indolent course than microbial keratitis
ususally a history of trauma from vegetation (e.g gardener)
takes a long time to heal

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19
Q

what are the features of orbital cellulitis?

A 
painful (esp. on eye movements)
proptosis
associated with paranasal sinusitis
pyrexial
sight threatening
swollen, red, puffy area around the eye
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20
Q

how is orbital cellulitis managed?

A

cared for by ENT and ophthalmology
CT scan to identify orbital abscesses if any suggestion of a restriction of muscles or optic nerve dysfunction (ask about red colour vision, follow finger etc)
broad spectrum AB and close monitoring
abscesses will require drainage

21
Q

what can cause orbital cellulitis?

A

direct extension from sinus
extension from focal orbital infection
post-operative

22
Q

what organisms can cause orbital cellulitis?

A 
staph
strep
coliforms
haemophilus influenzae
anaerobes
23
Q

what is endophthalmitis?

A

devastating infection inside of the eye

24
Q

what can cause endophthalmitis?

A 
post surgical (most common - leads to sudden blindness)
endogenous (spread from systemic infection in other areas of the body like endocarditis)
25
Q

how does endophthalmitis present?

A

very painful
decreasing vision
very red eye
sight threatening

26
Q

what organisms usually cause endophthlamitis?

A

often conjunctival commensals

most common = staph epidermidis

27
Q

how is endophthalmos managed?

A 
intravitreal
- amikacin
- ceftazidime
- vancomycin
- topical antibiotics
systemic antibiotics
28
Q

3 causes of chorioretinitis?

A

CMV in AIDS
Toxoplasma gondii
Toxocara canis (worms)

29
Q

what does CMV chorioretinitis look like?

A

many areas of exudate and haemorrhages in the retina

30
Q

where is toxoplasma gondii likely to come from?

A

cats and raw meat

31
Q

how does toxoplasmosis infection present?

A

mild flu like illness
can enter latent phase with cysts forming in an immunocomprimised patient
rarely causes further problems in healthy people

32
Q

how is toxoplasmosis managed?

A

can be left alone
requires systemic treatment is sight threatening
can reactivate

33
Q

what is toxocara?

A 
parasitic nematode (roundworm)
affects cats and dogs, unable to replicate in humans but remains an immature form of the worm
34
Q

what do toxocara do in the body?

A

often self limiting as they cannot replicate

form granulomas which can cause irreversible visual loss

35
Q

how are bacterial, chlamydial and viral eye infections diagnosed?

A

swabs for culture

36
Q

how is bacterial keratitis diagnosed?

A

corneal scrapes

37
Q

how is endophthalmitis diagnosed?

A

aqueous/vitreous for culture

38
Q

how is acanthamoeba diagnosed?

A

microscopy/culture

39
Q

how is toxoplasma and toxocara diagnosed?

A

serology

40
Q

what are the 3 broad categories of antibiotics?

A

inhibit protein synthesis
inhibit cell wall synthesis
inhibit nucleic acid synthesis

41
Q

what is the most commonly used topical antibiotic and what does it do?

A

chloramphenicol
inhibits peptidyl transferase enzyme which stops bacterial protein being made
bacteriocidal for strep and haemophilus
bacteriostatic for staph

42
Q

how can chloramphenicol be delivered and what are 3 possible side effects?

A 
ointment or dops
must be kept in the fridge
side effects:
- allergy
- irreversible aplastic anaemia (rare)
- grey baby syndrome (if too much given?)
43
Q

name 2 types of antibiotics which inhibit cell wall synthesis and how they work

A

penicillins and cephlasporins
both have a common B lactam ring
B lactam ring inhibits enzyme which makes bacterial cell wall
without cell wall, bacteria die

44
Q

name an antibiotic which inhibits nucleic acid synthesis can how

A

quinolones (e.g ofloxacin)
inhibits DNA gyrase (an enzyme which compresses bacterial DNA into supercoils)
inhibition of DNA gyrase leads to unwinding of supercoils and cell death

45
Q

name 3 common treatments for bacterial conjunctivitis

A

chloramphenicol = treats most apart from pseudomonas
fusidic acid = treats staph aureus
gentamicin = treats gram -ves - e.g coliforms, pseudomonas)

46
Q

name a commonly used antiviral and how it works

A 
acyclovir
inhibits viral DNA synthesis
base analogue (mimics guanine)
topical and systemic
used for dendritis ulcers of the cornea
47
Q

how is chlamydial conjunctivitis managed?

A

topical oxytetracycline

- adults may also need oral azithromycin for genital chlamydia infection

48
Q

name 2 treatments for bacterial keratitis

A

a 4-quinolone (ofloxacin) = treats most gram -ves but not strep pneumonia
gentamicin and cefuroxime = treats most gram +ve and -ves)

Opthamology (18 decks)

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