Microbiology in Ophthalmology

Question 1

what is an infection of the conjunctiva called

Answer 1

conjunctivitis

Question 2

what is an infection of the cornea called

Answer 2

keratitis

Question 3

what is an infection of the entire eye called

Answer 3

endophthalmitis

Question 4

what bacteria causes bacterial conjunctivitis in neonates

Answer 4

staph azures
neisseria gonorrhoea
chlamydia trachoma’s

Question 5

what bacteria causes bacterial conjunctivitis in all other ages

Answer 5

staph aures
strep pneumonia
haemophilus influenza (especially in children)

Question 6

how do you treat bacterial conjunctivitis

Answer 6

swab
topical antibiotic - chloramphenicol
drops/oitment

Question 7

when should you avoid using chloramphenicol in the treatment of bacterial conjunctivitis

Answer 7

history of aplastic anaemia or allergy

Question 8

what viruses cause viral conjunctivitis

Answer 8

adenovirus
herpes simplex
herpes zoster

Question 9

key difference in the presentation of viral vs bacterial conjunctivitis

Answer 9

bacterial - pussy discharge

Question 10

how does chlamydial conjunctivitis tend to present

Answer 10

chronic history
unresponsive to treatments
bilateral conjunctivitis in young adults
may or may not have vaginitis/urethritis
Looks like lots of little bumps under the eye lids- these can cause scarring to cornea so must be treated

Question 11

what can cause keratitis

Answer 11

bacteria
viruses
fungi

Question 12

what are the characteristics of bacterial keratitis

Answer 12

v rare
looks bad - v serious
white lump on cornea
level of white cells in the eye

Question 13

that is the treatment for bacterial keratitis

Answer 13

hourly drops - even over night so needs admission

Question 14

main risk factors for bacterial keratitis

Answer 14

contact lens wearers

other corneal pathology

Question 15

what viruses can cause viral keratitis

Answer 15

herpes

adenovirus

Question 16

characteristics of herpes keratitis

Answer 16

a dendritic ulcer on the eye - looks like bolt of lightening

v painful, recurrent

Question 17

what happens if herpes keratitis is treated with steroids

Answer 17

can cause corneal melt and perforation of the cornea

Question 18

characteristics of adenovirus keratitis

Answer 18

bilateral
follows URTI
contagious
sub epithelial infiltrates

Question 19

treatment for adenovirus keratitis

Answer 19

topical antibiotic to prevent secondary infection (bacterial keratitis can be caused by other corneal pathologies)

can require steroids to speed up recovery if it becomes chronic

Question 20

what fungi can cause keratitis

Answer 20

acanthamoeba

pseudomonas aeruginosa

Question 21

what is a hypopyon

Answer 21

inflammatory infiltrate built up in the eye - looks like a white line

Question 22

characteristics of fungal keratitis

Answer 22

not as painful as bacterial
history of trauma from vegetation
takes long time to heal

Question 23

what is orbital cellulitis

Answer 23

inflammation of eye tissues due to infection spread from the sinuses into the orbit

Question 24

characteristics of orbital cellulitis

Answer 24

painful - especially on eye movements
often associated with paranasal sinusitis
can compromise the optic nerve
swollen puffy red eye - skin around the eye is v swollen

Question 25

why is it important to differentiate between preseptal an orbital

Answer 25

because orbital can cause compartment syndrome

Question 26

what organisms cause orbital cellulitis

Answer 26

``` staph strep coliforms haemophilus influenzae anaerobes ```

Question 27

treatments for orbital cellulitis

Answer 27

if there's any signs of restriction of muscles or optic nerve dysfunction - scan give broad spectrum AB and monitor closely sometimes abscesses need drainage

Question 28

what is endophthalmitis

Answer 28

rare and devastating infection inside the eye v painful with decreasing vision - sight threatening

Question 29

what causes endophthalmitis

Answer 29

post surgical or endogenous ( if they have a systemic infection clumps of bacteria can get into the eye)

Question 30

treatment for endophthalmitis

Answer 30

difficult to treat infection inside eye - cut off from immune system intravitrial amikacin/ceftazimide/vancomycin systemic antibiotics given as well

Question 31

causative organisms of endophthalmitis

Answer 31

conjunctival commensals most common - staph epidermidis

Question 32

what is chorioretinitis

Answer 32

infection of the retina and choroid

Question 33

what causes chorioretinitis

Answer 33

cytomegalovirus seen in patents with AIDS Toxoplasma gondii toxocara Canis (worm)

Question 34

characteristics of toxoplasma gondii chorioretinitis

Answer 34

``` protozoa get it from cats and raw meat mild flu like illness rarely causes any other problems enters the latent phase with cysts forming needs treatment if life threatening ```

Question 35

characteristics of toxocara Canis

Answer 35

worm get it from cats and dogs unable to replicate in humans remains an immature form of worm (larvae) self limiting as cannot replicate form granulomas which can cause irreversible vision loss

Question 36

investigations for conjunctivitis

Answer 36

swabs for culture - bacterial, chlamydial, viral

Question 37

investigation for bacterial keratitis

Answer 37

corneal scape

Question 38

investigation for endophthalmitis

Answer 38

aqueous/vitreous culture

Question 39

investigation for ancanthamoeba

Answer 39

microscopy/culture | type of keratitis

Question 40

investigation for toxoplasma and toxocara

Answer 40

serology

Question 41

what are the 3 main ways antibiotics kill cells

Answer 41

inhibit cell protein synthesis inhibit cell wall synthesis inhibit nucleic acid synthesis

Question 42

what is the most commonly used antibiotic for eye infections

Answer 42

chloramphenicol

Question 43

how does chloramphenicol act

Answer 43

inhibits peptides transferase enzyme (therefore inhibits bacterial protein synthesis)

Question 44

what organisms is chloramphenicol bactericidal for

Answer 44

strep | haemophilus

Question 45

what organism is chloramphenicol bacterostatic for

Answer 45

staph

Question 46

side effects of chloramphenicol

Answer 46

allergy irreversible aplastic anaemia (v r are) grey baby syndrome

Question 47

what antibiotics inhibit cell wall synthesis

Answer 47

penicillins and cephalosporins - have common B lactic ring which inhibits the enzyme which makes the bacterial cell wall

Question 48

what antibiotics inhibit nucleic acid synthesis

Answer 48

quinolone eg. ofloxacin inhibit enzymes that compress bacterial DNA into supercoils inhibition of DNA gyrase leads to unwinding of DNA coils and cell death

Question 49

what is a common contaminate of eyedrops bottles

Answer 49

pseudomonas - eyedrop preservatives keep them clean of contaminants but only last 4 weeks

Question 50

antibiotics for bacterial conjunctivitis

Answer 50

chloramphenicol (treat most except pseudomonas) fusdic acid (treats staph aures) gentamicin (treats gram -ve bacterias including pseudomonas)

Question 51

what antivirals are used in viral eye infections

Answer 51

Aciclovir used for dendritic ulcers of the cornea

Question 52

what antibiotic is used for chlamydial conjunctivitis

Answer 52

topical oxytetracycline

Question 53

antibiotics for bacterial keratitis

Answer 53

Ofloxacin -treats most gram -ve but not strep pneumonia) gentamicin and cefuroxime (combination treats most gram + and -)