Microbiology in Ophthalmology

Question 1

what are common infecting organisms in neonatal bacterial conjunctivitis?

Answer 1

Staph aureus
niesseria gonorrhoea
chlamydia trachomatis

Question 2

True / False

all neonatal cases of bacterial conjunctivitis should be referred to ophthalmology?

Answer 2

True

Question 3

What is a common infecting organism of bacterial conjunctivitis in children?

Answer 3

Haemophilus influenzae

Question 4

What are some common infecting organisms in bacterial conjunctivitis?

Answer 4

Staph aureus
Strep pneumoniae
Haemophilus influenzae

Question 5

How is bacterial conjunctivitis treated?

Answer 5

Swab

Topical antibiotic usually chloramphenicol drops or ointment

Question 6

When should Chloramphenicol be avoided?

Answer 6

in aplastic anaemia

Question 7

What is the difference between bacterial and viral conjunctivitis?

Answer 7

Bacterial conjunctivitis produces a sticky discharge whereas viral conjunctivitis produces a watery discharge

Question 8

What are the common viral agents causing viral conjunctivitis?

Answer 8

Adenovirus
herpes simplex
herpes zoster

Question 9

In what type of conjunctivitis is there often a chronic history?

Answer 9

Chlamydial conjunctivitis

Question 10

In who and how does Chlamydial conjunctivitis often present?

Answer 10

bilaterally in young adults

Question 11

What can Chlamydial conjunctivitis cause?

Answer 11

sub tarsal scaring

Question 12

Where should microbial keratitis be treated?

Answer 12

in a hospital setting - can be sight threatening

Question 13

how does microbial keratitis present?

Answer 13

red eyes and corneal ulcers

Question 14

What is microbial keratitis associated with?

Answer 14

contact lens wearers

patients with another corneal pathology

Question 15

How is microbial keratitis diagnosed?

Answer 15

corneal scrape under anaesthetic

Question 16

what is typically seen in herpetic keratitis?

Answer 16

dendritic ulcer

very painful

Question 17

Why should herpetic keratitis not be treated with steroids?

Answer 17

can cause a corneal melt and perforation of the cornea

Question 18

What is the history and presentation of adenoviral keratitis?

Answer 18

subepithelial infiltrates
bilateral
usually following a URTI

Question 19

how is adenoviral keratitis treated?

Answer 19

with topical steroids to prevent secondary infection

can require steroids if chronic

Question 20

What is fungal keratitis often associated with?

Answer 20

history of trauma from vegetation

Question 21

What is the treatment of bacterial keratitis

Answer 21

A 4-quinolone (ofloxacin) -not active against strep. pneumoniae
Gentamicin and cefuroxime (will treat most gram +ve and -ve bacteria)

Question 22

What are the symptoms of orbital cellulitis?

Answer 22

painful - especially on eye movemetns
proptosis
pyrexia

Question 23

What is orbital cellulitis often associated with?

Answer 23

paranasal sinusitis

Question 24

What investigation is done in orbital cellulitis?

Answer 24

CT scan - identity orbital abscesses

Question 25

What are common infecting organisms in orbital cellulitis?

Answer 25

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

Question 26

What is the treatment for orbital cellulitis?

Answer 26

broad spectrum antibiotics close monitoring drainage of abscess

Question 27

What is endophthalmitis?

Answer 27

infection inside of the eye

Question 28

how does endophthalmitis present?

Answer 28

very painful decreasing vision very red eye sight threatening

Question 29

What causes endophthalmitis?

Answer 29

often conjunctival commensals following a surgical procedure

Question 30

What is the most common infecting organism in endophthalmitis

Answer 30

most common is staph epidermis - conjunctival commensal

Question 31

What is the treatment for endophthalmitis?

Answer 31

Intravitreal amikacin and vancomycin and topical antibiotics

Question 32

What are the common infecting organisms in Chorioretinitis

Answer 32

CMV in AIDs Toxoplasma gondii Toxocara canis (worm)

Question 33

what causes toxoplasmosis?

Answer 33

tics

Question 34

How does toxoplasmosis present?

Answer 34

mild flu like symptoms

Question 35

What type of treatment is given in toxoplasmosis? why?

Answer 35

systemic - sight threatening

Question 36

In bacterial, chalmydial and viral eye infection how is diagnosis made?

Answer 36

swabs for culture

Question 37

in bacterial keratitis how is diagnosis made?

Answer 37

corneal scrape under anaesthetic

Question 38

How is a diagnosis of endophthalmitis made?

Answer 38

Aqueous/vitreous for culture

Question 39

how is diagnosis of Chorioretinitis | made?

Answer 39

serology for toxoplasma / toxocara

Question 40

What is toxocara associated with?

Answer 40

cats and dogs

Question 41

what is the mechanism of Chloramphenicol?

Answer 41

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

Question 42

What are side effects of Chloramphenicol?

Answer 42

allergy irreversible aplastic anaemia grey baby syndrome

Question 43

how do penicillins and cephalosporins work?

Answer 43

• B lactam ring inhibits enzyme which makes bacterial cell wall • Without cell wall, bacteria die bactericidal

Question 44

give an example of a quinolone

Answer 44

ofloxacin

Question 45

how do quinolones work?

Answer 45

* inhibit DNA gyrase, an enzyme that compresses bacterial DNA into supercoils * Inhibition of DNA gyrase leads to unwinding of supercoils and cell death

Question 46

what organism is a common contaminant of eyedrops?

Answer 46

pseudomonas

Question 47

What drug is given for dendritic ulcers of the cornea?

Answer 47

acyclovir | NOT STEROIDS - CORNEAL MELT

Question 48

what drugs can be given in bacterial conjunctivitis?

Answer 48

Chloramphenicol Fusidic acid gentamicin

Question 49

What is Chloramphenicol effective against?

Answer 49

most bacteria except Pseudomonas aeruginosa

Question 50

what microorganism is fusidic acid effective against?

Answer 50

staph aureus

Question 51

What is gentamicin effective against?

Answer 51

most gram negative bacteria including coliform and pseudomonas aeruginosa

Question 52

what treatment is given for chlamydial conjunctivitis?

Answer 52

``` topical oxytetracycline oral azithromycin (if genital infection also present) ```