Microbiology

Question 1

How does bacterial conjunctivitis present?

Answer 1

Red eye and purulent discharge

Question 2

Name three common pathogens in neonatal conjunctivitis

Answer 2

Staph aureus
Neisseria gonorrhoea
Chlamydia trachomatis

Question 3

What should be done if you see neonatal conjunctivitis?

Answer 3

Urgent ophthalmology referral

Question 4

In other age groups what pathogens cause bacterial conjunctivitis?

Answer 4

Staph aureus
Strep pneumoniae
H.influenza (especially kids)

Question 5

How is bacterial conjunctivitis managed?

Answer 5

Swab 
Topical antibiotics (chloramphenicol QDS)

Question 6

When is chloramphenicol contraindicated?

Answer 6

Patients with a history of aplastic anaemia or patients with a chloramphenicol allergy

Question 7

What are the two types of chloramphenicol and what is the disadvantage of each?

Answer 7

Drops need to be kept in the fridge

Ointment can cause visual problems

Question 8

Name three causes of viral conjunctivitis

Answer 8

Adenovirus
Herpes Simplex
Herpes Zoster

Question 9

Describe adenoviral conjunctivitis

Answer 9

Pink eye, usually after URTI is highly contagious but does not require treatment

Question 10

What often occurs with herpes simplex conjunctivitis?

Answer 10

Associated skin rash

Question 11

What is Hutchison Sign and why does this occur?

Answer 11

Herpes zoster of the nasociliary branch of the ophthalmic division of the trigeminal nerve causes vesicles on the tip/side of nose and indicates eye involvement

Question 12

How does chlamydial conjunctivitis present?

Answer 12

Chronic history of conjunctivitis which is unresponsive to treatment - usually bilateral in young adults, low grade red eye but no discharge.

Question 13

What is the classic sign of chlamydial conjunctivitis?

Answer 13

Follicles on inner eyelid

Question 14

What can chlamydial conjunctivitis cause?

Answer 14

Sub tarsal scarring

Question 15

What is keratitis?

Answer 15

Infection of the cornea

Question 16

How does the cornea look when infected?

Answer 16

Cloudy as bacteria dislodges the natural arrangement

Question 17

Define hypopyon

Answer 17

Pus behind the eye

Question 18

How is bacterial keratitis managed?

Answer 18

Scraping for culture

Admission for hourly drops

Question 19

What is the serious complication of bacterial keratitis?

Answer 19

Perforation

Question 20

How does keratitis caused by herpes present?

Answer 20

Very painful and often recurrent infection with dendritic ulcers

Question 21

What stain can be used to see dendritic ulcers?

Answer 21

Flurocein

Question 22

What can recurrent herpes keratitis lead to?

Answer 22

Reduced corneal sensation

Question 23

What must not be given in herpes keratitis and why?

Answer 23

Steroids - risk of corneal melt and perforation

Question 24

How does adenovirus cause keratitis?

Answer 24

Autoimmune reaction post URTI

Question 25

What does adenovirus keratitis look like?

Answer 25

Bilateral subepithelial infiltrates and blurred vision

Question 26

Why are antibiotics given in adenovirus keratitis?

Answer 26

To prevent secondary infection

Question 27

What may be required if adenovirus keratitis becomes chronic?

Answer 27

Steroids

Question 28

Describe keratitis caused by fungi

Answer 28

Not as bad as bacterial, takes a few weeks to develop and usually has a history of trauma from vegetation

Question 29

How will fungal keratitis present?

Answer 29

Well defined ulcer that takes a long time to heal

Question 30

What infections are caused by contact lenses?

Answer 30

``` Acanthamoeba Pseudomonas aeruginosa (very painful) ```

Question 31

What is orbital cellulitis and how does it occur?

Answer 31

Pus in the orbit pushes the eye forward usually a direct extension from the sinus/focal orbital infection.

Question 32

How does a patient with orbital cellulitis present?

Answer 32

Proptosis, severe pain on movement, extremely unwell, pyrexic, well demarcated erythema

Question 33

Why is orbital cellulitis sight threatening?

Answer 33

It can cause damage to the optic nerve

Question 34

Name the pathogens associated with orbital cellulitis

Answer 34

``` Staphylococci Streptococci Coliforms H.influenza Anaerobes ```

Question 35

What investigation can be done on a patient with suspected orbital cellulitis?

Answer 35

CT scan

Question 36

What is the difference between preseptal and orbital cellulitis?

Answer 36

Preseptal - no compression of the nerve, less serious | Orbital - emergency, sight threatening compression of the nerve

Question 37

How is orbital cellulitis treated?

Answer 37

Broad spectrum antibiotics and drainage

Question 38

What is endophthalmitis?

Answer 38

Infection of the whole globe

Question 39

How does endophthalmitis present?

Answer 39

Usually 48 hours post surgery patients lose sight, extremely painful and red eye, systemically unwell

Question 40

How does endophthalmitis occur?

Answer 40

Blood retinal barrier is perforated resulting in infiltration of commensals such as staph epidermis

Question 41

What surgery is endophthalmitis a complication of?

Answer 41

Cataract surgery

Question 42

How is endophthalmitis managed?

Answer 42

Needle into vitreous to take culture and inject antibiotics

Question 43

Define chorioretinitis

Answer 43

Infection of the choroid and retina

Question 44

Name three causes of chorioretinitis

Answer 44

- CMV in AIDS and HSV - Toxoplasmosis Gondii - Toxocara Canis

Question 45

Describe toxoplasmosis gondii

Answer 45

Protozoan infection from cats and raw meat that causes a mild flu like illness and rarely further problems. Can sit in the eye in the latent phase but can reactivate

Question 46

What happens when toxoplasmosis gondii reactivates?

Answer 46

It interferes with vision and requires systemic therapy

Question 47

Describe toxocara canis

Answer 47

Roundworm affects cats/dogs but is unable to replicate in the human body so remain immature larvae, fairly self limiting

Question 48

What is the serious compilation of toxocara canis?

Answer 48

Granuloma formation and irreversible visual loss

Question 49

State four methods of diagnosis for eye infections

Answer 49

- swabs - corneal scrapes - aqueous/vitreous culture - serology

Question 50

What is dacrocystitis?

Answer 50

Lacrimal sac outflow is occluded which leads to bacterial proliferation

Question 51

How does chloramphenicol work?

Answer 51

Inhibits protein synthesis

Question 52

Is chloramphenicol bacteriostatic/cidal?

Answer 52

Bactericidal - strep and haemophillus | Bacteriostatic - staph

Question 53

What can be used for staph infections which don't respond to chloramphenicol?

Answer 53

Fusidic acid

Question 54

What can chloramphenicol cause?

Answer 54

Aplastic anaemia | Grey Baby Syndrome

Question 55

What quinolone is commonly used in keratitis?

Answer 55

Ofloxacin

Question 56

How do quinolones work?

Answer 56

Inhibit DNA synthesis

Question 57

Why should use of ofloxacin be monitored closely?

Answer 57

Antibiotic resistance

Question 58

What bacteria is a common contaminant?

Answer 58

Pseudomonas

Question 59

What can be used to treat gram negative bacteria?

Answer 59

Gentamicin

Question 60

How does acyclovir work?

Answer 60

Mimics G base to inhibit DNA synthesis - used to treat dendritic corneal ulcers

Question 61

What is the treatment for chlamydial conjunctivitis?

Answer 61

Oxytetracycline (adults may also need treatment for genital chlamydia)