Microbiology

Question 1

Conjunctivitis

Answer 1

Inflammation of the conjunctiva (skin of the eye)

Question 2

Conjunctivitis features

Answer 2

Red and swollen conjunctiva
Watery or pus-containing discharge
Discomfort

Question 3

Bacterial Conjunctivitis Aetiology neonates

Answer 3

Staph Aureus
Neisseria Gonorrhoea
Chlamydia Trachomatic

Refer all cases to ophthalmology

Question 4

Bacterial conjunctivitis aetiology

Answer 4

Staph Aureus
Step Pneumonia
H.influenzae (especially children)

Question 5

Bacterial conjunctivitis treatment

Answer 5

Swab 
Topical antibiotic (chloramphenicol) 

Avoid chloramphenicol if history of aplastic anaemia or allergy

Question 6

Viral Conjunctivitis Aetiology

Answer 6

Adenovirus
Herpes Simplex
Herpes Zoster

Question 7

Viral Conjunctivitis Treatment

Answer 7

Anti-virals for herpes

Topical lubricants for adenovirus

Question 8

Chlamydial Conjunctivitis

Answer 8

often chronic history and unresponsive to treatments

Suspect in bilateral conjunctivitis in young adults

+/- symptoms of urethritis, vaginitis

need contact tracing

Question 9

Chlamydial conjunctivitis consequence

Answer 9

Subtarsal scarring

Question 10

Keratitis

Answer 10

Inflammation of the cornea of the eye

Question 11

Microbial Keratitis

Answer 11

bacteria
viruses
fungi
acanthamoeba

Question 12

Bacterial keratitis

Answer 12

Need admission for hourly drops
Daily review

Usually in association with other corneal pathology or contact lens wear

Question 13

Viral Keratitis Aetiology

Answer 13

herpes

adenovirus

Question 14

Herpetic keratitis feature

Answer 14

Dendritic Ulcer
- very painful and can be recurrent

Recurrence usually results in reduced corneal sensation

Question 15

herpetic keratitis Treatment

Answer 15

Topical antiviral (ganciclovir)

NO STEROIDS (can cause corneal melt and perforation of cornea)

Question 16

Adenoviral Keratitis features

Answer 16

Sub Epithelial infiltrates

Normally bilateral
Usually follows an URTI/ conjunctivitis
May affect vision

Question 17

Adenoviral Keratitis Treatment

Answer 17

Usually self-limiting

May require steroids to speed up recovery if chronic + vision problems

Question 18

Fungal keratitis - epidemiology and features

Answer 18

Often chronic history

Work outside or have ocular surface disease

Corneal lesions (more defined than bacterial keratitis )

often diagnosed late

Question 19

Fungal keratitis treatment

Answer 19

Topical anti-fungals

- natamycin amphotericin

Question 20

Acanthamoeba keratitis

Answer 20

Contact lenses
Often extremely painful- can be diagnosed late
Culture contact lenses

Question 21

Orbital Cellulitis Organisms

Answer 21

Staphylococci 
Streptococci 
Coliforms 
H.influenzae 
Anaerobes

Question 22

Orbital Cellulitis Features

Answer 22

painful (especially on eye movement)

proptosis (forward displacement of eye- exophthalmos)

Often associated with paranasal sinusitis

Pyrexial

Sight threatening

Question 23

Orbital Cellulitis Investigation

Answer 23

CT scan

- identify orbital abscesses

Question 24

Orbital Cellulitis pattern of spread

Answer 24

Direct extension from sinus
Extension from focal orbital infection
Post-operative

Question 25

Orbital Cellulitis management

Answer 25

Suggestion of restriction of muscles or optic nerve dysfunction --> scan Broad spectrum antibiotic and monitor

Question 26

Endophthalmitis

Answer 26

Inflammation, usually due to infection, within the eye | - Devastating infection

Question 27

Endophthalmitis Features

Answer 27

Post surgical or endogenous Very painful and decreasing vision Very red eye Sight threatening

Question 28

Endophthalmitis Organisms

Answer 28

Commensals | - Mainly staph epidermis

Question 29

Endophthalmitis Treatment

Answer 29

Intravitreal amikacin/ ceflazidime and topical antibiotics

Question 30

Chorioretinitis

Answer 30

Inflammation involving both the choroid and retina Very rare 9mainly seen in immunocompromised

Question 31

Chorioretinitis Organisms

Answer 31

``` CMV in AIDs HSV/ HZV Endogenous (candida) Toxoplasma Gondii Toxocara canis (worm) ```

Question 32

Toxoplasmosis aetiology

Answer 32

Protozoan Infection Congenital or acquired - contaminated soil or undercooked meat

Question 33

Toxoplasmosis features

Answer 33

Mild flu like illness Immunocompetent patients - latent phase with cysts forming Rarely causes a problem

Question 34

Toxoplasmosis Treatment

Answer 34

Rarely requires treatment Systemic treatment if cysts become sight threatening

Question 35

Diagnosis of eye infections

Answer 35

Swabs for culture - bacterial - chlamydial - viral Aqueous/ nitrous culture in endophthalmitis Microscopy/ culture for acanthoemeba Serology for toxoplasma and toxocara

Question 36

Antibiotics- mechanisms of action (3)

Answer 36

Inhibit protein synthesis Inhibit cell wall synthesis inhibit nucleic acid synthesis

Question 37

Chloramphenicol

Answer 37

Inhibits peptide transferable enzyme Bacteriocidal - strep and haemophilis Bacteriostatic - staph

Question 38

Chloramphenicol Side effects

Answer 38

allergy irreversible aplastic anaemia grey baby syndrome

Question 39

bacterial keratitis antibiotics

Answer 39

4-quinolone (Ofloxacin) - Gram -ve - NOT active vs strep pneumonia Gentamicin and Cefuroxime - Gram +ve and Gram -ve

Question 40

bacterial conjunctivitis antibiotics

Answer 40

Chloramphenicol - treats most except pseudomonas aeruginosa Fusidic acid - Staph aureus Gentamicin - Gram -ve

Question 41

Antivirals

Answer 41

Ganciclovir - Inhibits viral DNA synthesis - base analogue - Topical and systemic - tears dendritic ulcers of cornea

Question 42

Chlamydial Conjunctivitis treatment

Answer 42

Topical oxytracycline