week 1 microbiology

Question 1

name a gram +ive cocci

Answer 1

strep, staph

Question 2

what is keratitis

Answer 2

inflammation of cornea

Question 3

name a gram -ive cocci

Answer 3

neisseria

Question 4

name a gram -ive cocci-bacilli

Answer 4

h.influenzae

Question 5

name a gram -ive bacilli

Answer 5

psuedomonas

Question 6

what is endophthalmitis

Answer 6

entire globe inflammation

Question 7

infection of skin round eye

Answer 7

infection/inflammation of the eye skin

Question 8

what can conjunctivitis be cause by

Answer 8

viral and bacterial

Question 9

how to tell difference between bacterial and viral conjunctivitis?

Answer 9

bacterial = pus (lots)
viral = watery

Question 10

common infective organisms in bacterial conjunctivitis in newborn/baby

Answer 10

Staph aureus
Neisseria gonorrhoeae
Chlamydia trachomatis

(refer all cases to ophthalmology)

Question 11

common infective organisms in bacterial conjunctivitis in adult

Answer 11

Staph aureus
Strep pneumoniae
Haemophilus influenzae (especially in children)

Question 12

treatment for bacterial conjunctivitis

Answer 12

Swab

Topical antibiotic usually chloramphenical qds, (drops vs ointment)

if not responding then culture will give answer

Question 13

what is difference between drops and ointment for chloramphenicol

Answer 13

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

Question 14

contraindications of using chloramphenicol

Answer 14

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

Question 15

what are the main organisms causing viral conjunctivitis

Answer 15

Adenovirus
Herpes simplex
Herpes zoster

Question 16

treating viral conjunctivitis

Answer 16

swab not usually necessary (can PCR if necessary).

sometimes antibiotics given to prevent secondary infection

Question 17

herpes zoster ophthalmicus symptoms

Answer 17

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

Question 18

what are the 4 CN with parasympathetic function

Answer 18

3, 7, 9, 10

Question 19

treatment for herpes zoster ophthalmicus

Answer 19

antivirus within 72hrs

Question 20

chlamydial conjunctivits PC

Answer 20

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.

Question 21

causes of keratitis

Answer 21

Bacteria
Viruses
Fungi

Question 22

how can you differential bacterial/fungal keratitis from viral

Answer 22

hypopyon (sight threatening disease)

Question 23

treatment for Bacterial keratitis

Answer 23

Need admission for hourly drops
Daily review
can perforate=bad

Question 24

risk factors for bacterial keratitis

Answer 24

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

Question 25

what are the causative organisms of viral keratitis

Answer 25

herpes, adenovirus

Question 26

what is a common finding with Herpetic keratitis

Answer 26

dendritic ulcer

Question 27

PC of bacterial keratitis

Answer 27

painful red eye, short Hx, reduced vision

Question 28

PC of herpetic keratitis

Answer 28

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

Question 29

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

Answer 29

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

Question 30

what is seen in adenovirus keratitis?

Answer 30

superepithlial infiltrates

Question 31

PC of adenoviral keratitis

Answer 31

Bilateral Usually follows an URTI Contagious may affect vision

Question 32

treatment of adenoviral keratitis

Answer 32

Can give topical AB to prevent secondary infection Can require steroids to speed up recovery if becomes chronic

Question 33

keratitis use by contact lenses (organisms)?

Answer 33

Acanthamoeba | Pseudomonas aeruginosa

Question 34

PC fungal keratitis

Answer 34

less aggressive than microbial keratitis Usually a history of trauma from vegetation - farmer. healing takes a long time

Question 35

orbital cellulitis PC

Answer 35

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

Question 36

investigation of orbital cellulitis

Answer 36

Cared for by ENT and Ophthalmology(admit) CT scan to identify orbital abscesses

Question 37

how to distinguish between between preseptal and orbital cellulitis

Answer 37

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

Question 38

causative organisms of orbital cellulitis

Answer 38

``` Staphylococci Streptococci Coliforms Haemophilus influenzae anaerobes ```

Question 39

orbital cellulitus treatment

Answer 39

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

Question 40

what is endopthalmitis? why does it occur?

Answer 40

Devastating infection inside of the eye Post-surgical or endogenous

Question 41

PC of Endophthalmitis

Answer 41

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

Question 42

most common organism causing Endophthalmitis?

Answer 42

Often conjunctival “commensals” Most common is staph epidermidis

Question 43

treatment of Endophthalmitis?

Answer 43

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)

Question 44

what is Chorioretinitis

Answer 44

inflammation of back of the eye/retina

Question 45

causes of Chorioretinitis

Answer 45

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

Question 46

what is the pizza-pie sign seen in?

Answer 46

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

Question 47

what causes toxoplasmosis? what type of infection is this?

Answer 47

Toxoplasma gondii | protozoal infection

Question 48

key facts about toxoplasmosis (Chorioretinitis)

Answer 48

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

Question 49

treatment of toxoplasmosis Chorioretinitis

Answer 49

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

Question 50

toxocara canis (worms) keys facts

Answer 50

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

Question 51

how to diagnose bacterial keratitis

Answer 51

corneal scrapes

Question 52

how to diagnose endophthalmitis

Answer 52

Aqueous/vitreous for culture

Question 53

how to diagnose acanthamoeba in eye

Answer 53

microscopy/culture

Question 54

how to diagnose toxoplasma or toxicara in eye

Answer 54

serology

Question 55

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

Answer 55

Swabs for culture

Question 56

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

Answer 56

Chloramphenicol

Question 57

how does Chloramphenicol work?

Answer 57

-Inhibits peptidyl transferase enzyme (therefore stops bacterial protein being made) - Bacterocidal for strep and haemophilus - Bacterostatic for staph

Question 58

side effects of Chloramphenicol

Answer 58

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

Question 59

what antibiotics inhibit cell wall synthesis?

Answer 59

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

Question 60

what is Dacryocystitis?

Answer 60

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

Question 61

what antibiotics inhibit nucleic acid synthesis?

Answer 61

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]

Question 62

when is only case ofloxacin should be used? why?

Answer 62

bacterial keratitis. to prevent resistance

Question 63

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

Answer 63

Pseudomonas

Question 64

how to treat bacterial conjunctivitis?

Answer 64

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

Question 65

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

Answer 65

anti-viral, topical/systemic. used for detritus ulcer in cornea to stop preforation

Question 66

how does acyclovir work ?

Answer 66

``` Aciclovir inhibits viral DNA synthesis Base analogue (mimics guanine) ```

Question 67

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

Answer 67

steroids can be once slit lamp shows no dendritic ulcer

Question 68

how to treat Chlamydial conjunctivitis

Answer 68

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

Question 69

how to treat bacterial keratitis?

Answer 69

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)