Microbiology

Question 1

What is the term for inflammation of the conjunctiva?

Answer 1

Conjunctivitis

Question 2

What is the term for inflammation of the cornea?

Answer 2

Keratitis

Question 3

What is the term for inflammation of the entire globe (orbit etc.)

Answer 3

Endophthalmitis

Question 4

What are the common pathogens for neonatal bacterial conjunctivitis?

Answer 4

Staph aureus
Neisseria gonorrhoea
Chlamydia trachomatis

Question 5

When would a neonatal conjunctivitis case be referred to ophthalmology?

Answer 5

Always

Question 6

What is the commonest bacterial cause of conjunctivitis in children?

Answer 6

Haemophilus influenzae

Question 7

What are the common bacteria causing conjunctivitis in adults?

Answer 7

Staph aureus

Strep pneumoniae

Question 8

What antibiotic is typically used for bacterial conjunctivitis?

Answer 8

Topical chloramphenical

Unless history of aplastic anaemia it allergy

Question 9

What are the main viral causes of conjunctivitis?

Answer 9

Adenovirus
Herpes simplex
Herpes zoster

Question 10

What should you suspect when a young adult presents with bilateral conjunctivitis?

Answer 10

Chlamydia conjunctivitis

Question 11

What can a sign of progressive chlamydial conjunctivitis be?

Answer 11

Subtarsal scarring

Question 12

What is the physical description of an eye with bacterial keratosis?

Answer 12

Red eye
Reduced vision
White lesion in cornea (sits at the bottom +/- patch over central iris)

Question 13

What is the pathophysiology of white lesions in the cornea?

Answer 13

The usually very organised collagen fibres in the cornea have been disturbed by the bacterial infiltration

Question 14

What is the treatment plan for people with bacteria keratitis?

Answer 14

Admission for 48 hours - hourly eye drops

Question 15

What typically gives you clues towards a diagnosis of bacterial keratitis?

Answer 15

Other corneal pathology

Contact lens wearers

Question 16

What keratitis is more likely to occur in someone with a previously non-pathological cornea?

Answer 16

Viral kerititis

Question 17

What is the sign of herpetic keratitis?

Answer 17

Dendritic ulcers

Question 18

What is unfortunate about having a herpetic keratitis?

Answer 18

It is very painful
It can be recurrent
And recurrence can cause eventual reduced corneal sensation
Higher risk of developing bacterial keratitis

Question 19

What must you never treat herpetic keratitis with?

Answer 19

Steroids

Question 20

What is a typical sign of adenoviral keratitis?

Answer 20

Subepithelial infiltrates

Question 21

What pathologies are associated with adenoviral keratitis?

Answer 21

Conjunctivitis

Respiratory infection

Question 22

Are adenoviral keratitis infections bilateral or unilateral?

Answer 22

Bilateral

Question 23

Are adenoviral keratitis infections contagious?

Answer 23

YES

Question 24

What would you prescribe to treat adenoviral keratitis?

Answer 24

Topical antibody- prevent secondary infection

Steroids to speed up recovery (if condition chronic)- BUT ONLY IF CERTAIN IT ISN’T HERPETIC KERATITIS

Question 25

What is the likely pathogens for keratitis caused by washing contact lenses in tap water?

Answer 25

Acanthamoeba | Pseudomonas aeruginosa

Question 26

What would the causative pathogen for a keratitis resulting from a trauma associated with vegetation be?

Answer 26

Fungal pathogen

Question 27

What would you treat fungal keratitis with?

Answer 27

Have to try different things as very difficult and long healing process Often need corneal grafts

Question 28

What is the typical presentation of an orbital cellulitis?

Answer 28

Extremely painful (especially on eye movements) Associated Paranasal sinusitis Pyrexia Proptisis (protruding eye)

Question 29

Why would you CT someone with orbital cellulitis?

Answer 29

To check for and identify orbital abscesses

Question 30

What is the most common cause of orbital cellulitis?

Answer 30

Infection from skin commensals post operatively

Question 31

What must you differentiate orbital cellulitis from?

Answer 31

Preseptal cellulitis (when it’s just the outer surface of the skin- should have no altered structure and function of the eye)

Question 32

What are the organisms that can cause orbital cellulitis?

Answer 32

``` Staphylococci (epi/aureus) Streptococci California Haemophilus influenzae Anaerobes ```

Question 33

What would you do to manage orbital cellulitis?

Answer 33

Examine routinely to check for restriction of muscles or optic nerve dysfunction (CT scan if so) Broad spectrum antibiotics and close monitoring Possibly drain abscesses

Question 34

What is the rarest and most devastating eye infection? | And what often the cause

Answer 34

Endophthalmititis | Post surgical infection

Question 35

What are some endogenous causes of endophthalmitis?

Answer 35

Bacterial endocarditis etc.

Question 36

What does endophthalmitis present as?

Answer 36

Very red eye Extremely painful Decreasing vision

Question 37

What is the most common organism causing endophthalmitis?

Answer 37

Staph epidermidis

Question 38

How do you treat endophthalmitis?

Answer 38

Intravitreal (inside posterior eye) amakacin/ceftazidime/vancomycin Topical antibiotics Possible systemic antibiotics

Question 39

What are causes of chorioretinitis?

Answer 39

Cytomegalovirus in AIDS (much rarer now) Toxoplasma Gondi Tococara canis (worm)

Question 40

What was a previously common ocular presentation of aids?

Answer 40

Haemorrhagic cytomegalovirus retinitis

Question 41

Where might a person contract toxoplasmosis?

Answer 41

Cats | Raw meat

Question 42

What does toxoplasmosis present as?

Answer 42

Mild flu-like illness | In the immunocompromised- latent phase with cyst formation

Question 43

Is toxoplasmosis recurrent?

Answer 43

Yes in the immunocompromised

Question 44

Can the toxocara worm replicate in humans? | And what damage does it do?

Answer 44

No, but it lives as an immature larvae form of the worm It forms granulomas—> lead to irreversible visual loss

Question 45

How do you diagnose and eye infection?

Answer 45

Swan for culture (bacterial, chlamydial, viral) Corneal scrapes (bacterial keratitis) Aqueous/vitreal humour for culture (endophthalmitis) Microscopy/culture for acanthamoeba (of contact lenses too) Serology (toxoplasma, toxocara)

Question 46

What is the most common topical antibiotic for eye infections?

Answer 46

Chloramphenicol

Question 47

How does chloramphenicol work?

Answer 47

Inhibits peptides transferase enzyme (prevents bacterial protein synthesis) Kills strep and haemophilus Slows down staph

Question 48

What are chloramphenicol’s side effects?

Answer 48

Allergy Irreversible aplastic anaemia Grey baby syndrome

Question 49

What is a common bottle contaminant?

Answer 49

Pseudomonas | Dispose of bottles after 4 weeks

Question 50

What can psueudomonas cause in the eye?

Answer 50

Ulcers

Question 51

What would you treat a staph aureus conjunctivitis with?

Answer 51

Fusidic acid

Question 52

What would you treat most conjunctivitis infections with?

Answer 52

Chloramphenicol

Question 53

What would you treat a gram negative conjunctivitis with?

Answer 53

Gentimicin

Question 54

What antiviral can be used for viral keratitis?

Answer 54

Aciclovir

Question 55

What do you treat chlamydial conjunctivitis with?

Answer 55

Topical oxytetracycline | Oral azithromycin if genital chlamydia too

Question 56

What would you treat keratitis caused by gram negative, pseudomonas areuginosa, haemophilus influenzae?

Answer 56

Ofloxavcin (4-quinolone)

Question 57

What would you treat a keratitis caused by most gram positive/negative organisms?

Answer 57

Gentamicin and cefuroxime