Microbiology

Question 1

What is the Gram appearance of Neisseria species?

Answer 1

Gram negative cocci

Question 2

What is the Gram appearance of Pseudomonas species?

Answer 2

Gram negative bacilli

Question 3

Keratitis is

Answer 3

Inflammation of the cornea

Question 4

Endopthalmitis is inflammation of the

Answer 4

Entire globe

Question 5

Commonest 3 causes of neonatal conjunctivitis?

Answer 5

1) S. aureus 2) N. gonorrhoea 3) C. trachomatis Refer ALL neonatal conjunctivitis to ophthalmology

Question 6

Commonest 3 causes of bacterial conjunctivitis (non-neonate)?

Answer 6

1) S. aureus 2) S. pneumoniae 3) H. influenzae

Question 7

Where should a swab for bacterial conjunctivitis be taken?

Answer 7

Fornix (using analgesic drops)

Question 8

What’s the standard treatment for bacterial conjunctivitis?

Answer 8

Chloramphenicol drops QDS

Question 9

Chloramphenicol must be avoided in which history

Answer 9

Aplastic anaemia or allergy

Question 10

Commonest 3 causes of viral conjunctivitis

Answer 10

Adenovirus Herpes zoster Herpes simplex

Question 11

What illness tends to precede a viral conjunctivitis?

Answer 11

Upper RTI

Question 12

What’s the main symptom/sign difference between bacterial & viral conjunctivitis?

Answer 12

Viral tends to be a more watery discharge. Bacterial tends to be mucus discharge.

Question 13

What should raise suspicion of chlamydia conjunctivitis? (3)

Answer 13

Chronic eye infection, unresponsive to treatment, bilateral infection (if young adults).

Question 14

Why is it important to define and diagnose cases of chlamydia?

Answer 14

Needs contact tracing

Question 15

“Rice-grain follicles” is pathognomonic of which infection?

Answer 15

Chlamydia conjunctivitis

Question 16

Why is chlamydia serious in eye infections?

Answer 16

Can cause irreversible scarring

Question 17

A collection of white cells in the anterior eye is termed what?

Answer 17

Hypopyon

Question 18

What is the treatment for bacterial keratitis like? (3)

Answer 18

1) Hourly eye drops (Day and night) 2) Scalpel to remove tissue for microbiology C&S 3) Daily review

Question 19

Dendritic ulcer in the eye is characteristic of which type of infection?

Answer 19

Viral (especially herpes)

Question 20

T/F: Herpetic keratitis is usually painless.

Answer 20

False - very painful

Question 21

Which medication class is absolutely contraindicated in herpetic keratitis? Why is this particular medication sometimes still used?

Answer 21

Steroids (can cause a corneal melt and perforated cornea). Clinicians sometimes confuse herpetic keratitis with uveitis (inflamamtion) and prescribe steroids.

Question 22

How is herpetic keratitis treated?

Answer 22

Zyvrax.

Question 23

A geographical ulcer is indicative of what

Answer 23

A patient who was given steroids to treat their herpetic keratitis (causing an ulcer/ perforation of eyeball)

Question 24

Which viral infection causes darkening of the cornea?

Answer 24

Adenoviral keratitis

Question 25

Are steroids contraindicated in adenoviral keratitis?

Answer 25

No (c.f. herpetic keratitis), sometimes they are needed to improve recovery if the condition ebcomes chronic

Question 26

Adenoviral keratitis tends to follow which infection

Answer 26

URTI

Question 27

Subepithelial infilitrates is pathognomonic for...

Answer 27

Adenoviral keratitis

Question 28

Common fungal causes of keratitis include?

Answer 28

Acanthamoeba

Question 29

Which viruses cause keratitis?

Answer 29

Herpes, adenoviral

Question 30

Is hypopyon specific to bacterial keratitis?

Answer 30

No

Question 31

Fungal keratitis tends to proceed faster/slower than microbial keratitis. What is the common factor elicited in history?

Answer 31

Slower. Tends to be a history of trauma involving vegetables.

Question 32

Orbital cellulitis is often painless, T/F?

Answer 32

False - painful on eye movement especially.

Question 33

Orbital cellulitis can be sight-threatening, T/F?

Answer 33

True

Question 34

What investigation must be performed in orbital cellulitis & why?

Answer 34

Head CT. Identify orbital abscesses.

Question 35

How can orbital cellulitis be differentiated from other infections involving the eye?

Answer 35

Patients will be pyrexial, have proptosis, pain will be worsened by moving eye.

Question 36

What are the causes of orbital cellulitis? (3)

Answer 36

1) Direct extension from sinus 2) Extension from focal orbital infection 3) Post-operative

Question 37

Which organisms are commonly implicated in orbital cellulitis? (4)

Answer 37

1) Staph 2) Streps 3) Coliforms 4) H. influenzae

Question 38

Orbital cellulitis treatment regimen?

Answer 38

Broad-spectrum antibiotics, drainage of abscess if present

Question 39

Endophthalmitis is generally painless, T/F?

Answer 39

False: Extremely painful

Question 40

Commonest organisms implicated in endophthalmitis? (2)

Answer 40

1) S. epidermidis 2) Conjunctival commensals

Question 41

How is endophthalmitis treated?

Answer 41

Intravitreal antibiotics (amikacin/ ceftazidime/ vancomycin) and topical antibiotics

Question 42

Commonest organisms causing chorioretinitis?

Answer 42

1) CMV (in AIDS) 2) T. gondii 3) Toxocara canis (worm)

Question 43

What kind of symptoms does toxoplasmosis usually present with?

Answer 43

A mild, flu-like illness.

Question 44

Toxocara canis is what type of worm

Answer 44

Nematode (roundworm)

Question 45

How does Toxocara canis cause visual loss?

Answer 45

Forms granulomas in the eye which cause irreversible visual loss

Question 46

Which sample is needed for C&S in suspected endopthalmitis?

Answer 46

Aqueous/ vitreous sample

Question 47

Which sample is needed for toxoplasma and toxocara infection?

Answer 47

Blood (for serology)

Question 48

What sample is needed for diagnosis of bacterial keratitis?

Answer 48

Corneal scrapes

Question 49

Which sample is needed to diagnose ocular chlamydia (or conjunctivitis)?

Answer 49

Fornix swab

Question 50

Broadly, what's the MoA of chloramphenicol?

Answer 50

Bacterial protein synthesis inhibitor

Question 51

Is chloramphenicol bacteriocidal for staphs?

Answer 51

No (only bacteriostatic)

Question 52

What are the 3 main side effects of chloramphenicol?

Answer 52

1) Allergy 2) Irreversible aplastic anaemia 3) Grey-baby syndrome

Question 53

Dacrocystitis is blockage of which structure

Answer 53

Lacrimal duct

Question 54

Broadly, what is the MoA of quinolones?

Answer 54

Inhibit DNA synthesis (ex: ciprofloxacin)

Question 55

What's the standard antibiotic of choice for bacterial conjunctivitis? What should be used if allergic to this? What's the important exception?

Answer 55

Common antibiotic = chloramphenicol If allergic = Fusidic acid Exception is Pseudomonas, use gentamicin.

Question 56

Aciclovir inhibits viral DNA synthesis how

Answer 56

Mimics guanine, prevents replication

Question 57

How should you differentiate uveitis from herpetic keratitis?

Answer 57

Slit lamp exam

Question 58

How is ocular chlamydia treated? How is the genital form of chlamydia treated?

Answer 58

Ocular form = topical oxytetracycline. Genital form = Oral azithromycin

Question 59

Spot Diagnosis

Answer 59

Dendritic ulcer (herpetic keratitis)

Question 60

What is this structure?

Answer 60

Hypopyon (collection of dead WBCs in anterior chamber of anterior segment)

Question 61

What is this sign? What is it indicative of?

Answer 61

Rice-grain follicle. Indicative of chlamydia infection.

Question 62

Spot Diagnosis

Answer 62

Herpes simplex conjunctivitis

Question 63

Spot diagnosis & what is this infection associated with?

Answer 63

Fungal keratitis -\> associated with contact lenses

Question 64

Spot diagnosis

Answer 64

Orbital cellulitis