Microbiology Flashcards
What bacteria can cause conjunctivitis in neonates?
Staphylococcus aureus
Neisseria gonorrhoea
Chlamydia trachomatis
What bacteria commonly cause conjunctivitis in all bar neonates?
Staphylococcus aureus
Streptococcus pneumoniae
Haemophilus influenzae (esp in children)
What is conjunctivitis?
Inflammation of the conjunctiva
What are the common symptoms of bacterial conjunctivitis?
Minimal pain Sticky eye Purulent discharge Red eye Spreads between eyes Clear cornea Normal pupillary response
How is conjunctivitis diagnosed?
Swab
How is conjunctivitis treated?
Chloramphenicol If neonate - ophthalmology Fusidic acid if staphyloccous aureus Pseudomonas - gentamicin Chlamydia - oxytetracycline and azithromycin
What are the side effects of chloramphenicol?
Aplastic anaemia
Grey baby syndrome
What viruses commonly cause viral conjunctivitis?
Adenovirus
Herpes simplex
Herpes zoster
What are the symptoms of viral conjunctivitis?
Swollen and tender preauricular lymph nodes Watery eye Red eye Extreme eye movements can be painful Tends to occur with URTI
How will herpes simplex conjunctivitis present?
Vesicles around eyes that spreads to eye
What must be done in a patient with chlamydial conjunctivitis?
Contact tracing
How will chlamydial conjunctivitis present?
Follicular changes in eyelid
What can untreated chlamydial conjunctivitis cause?
Subtarsal scarring
Damage to cornea or dry eye
What is the classical sign of bacterial keratitis?
Hypopyon Pain Photophobia Reduced visual acuity Epiphora Red eye Opacity
How is bacterial keratitis (corneal ulcer) treated?
Hourly drops for 48hrs in hospital
Daily review
How can a bacterial keratitis occur?
In association with other corneal pathology or contact lens wear
What bacteria can cause bacterial keratitis?
Staphylococcus aureus
Streptococcus
Pseudomonas
What viruses can cause keratitis?
Herpes simplex
Adenovirus
How can viral keratitis occu?
In a normal cornea
What is the characteristic sign of herpetic keratitis?
Dendritic ulcer
What are the symptoms of herpetic keratitis?
Very painful
Can be recurrent
Recurrences eventually result in reduced corneal sensation
Why should herpetic keratitis NOT be treated with steroids?
Corneal melt and perforation of the cornea
Where does herpes simplex reside?
In the trigeminal nerve - will reactivate
What is the characteristic sign of adenoviral keratitis?
Subepithelial infiltrates
Reduced vision
How is adenoviral keratitis treated?
Topical antibiotic to prevent secondary infection
Artificial tears
Steroids to speed up recovery if chronic and you are SURE it is not herpetic
What keratitis is associated with contact lens wearing?
Acanthamoeba
Pseudomonas aeruginosa
What is the disease progression of fungal keratitis?
More indolent that microbial
Usually a history of trauma from vegetation
Takes a long time to heal
What are the symptoms of orbital cellulitis?
Painful on eye movements Proptosis Paranasal sinusitis Pyrexial Sight threatening Cared for by ENT and ophthalmology
What investigation is required in suspicion of orbital cellulitis?
CT scan
Compartment syndrome
Can compromise the optic nerve
How does orbital cellulitis occur?
Direct extension from sinus
Extension from focal orbital infection (infected chalazion, dacryocystitis)
Post-op
What organisms commonly cause orbital cellulitis?
Staphylococci Streptococci Coliforms Haemophilus influenzae Anaerobes
How is orbital cellulitis treated?
Broad spectrum antibiotics and monitor closely
Abscess will require drainage
What is endophthalmitis?
Devastating infection inside of eye Post-surgical or endogenous Painful +++ with decreasing vision V red eye Sight threatening
What bacteria can cause endophthalmitis?
Conjunctival commensals
Staphylococcus epidermis
How is endophthalmitis treated?
Intravitreal amikacin/ cefazidime/ vancomycin
Topical antibiotics
Systemic antibiotics
What is chorioretinitis?
Infection of the choroid of retina
What can cause chorioretinitis?
Cytomegalovirus
Toxoplasma gondii
Toxocara canis
What will CMV retinitis look like under fundoscopy?
Huge areas of exudation and haemorrhage
How is CMV retinitis treated?
Injections in eye
How is keratitis diagnosed?
Fluorescein
Corneal scrape
What is endophthalmitis?
Inflammation of the intraocular space occupied by vitreous humor
What is blepharitis?`
Inflammation of the eyelids
What can cause anterior blepharitis?
Seborrhoeic dermatitis
Staph aureus
What can cause posterior blepharitis?
Acne rosacea
Meibomian gland dysfunction
What are the symptoms of blepharitis?
Itchy, sore, red eyelid Burning sensation in eyes Photophobia Swollen eyelid margins Cysts
What is dacryocystitis?
Blockage of lacrimal system
How is dacryocystitis treated?
Broad spectrum antibiotics
What is a chalazion?
Meiboman cyst treated with heat and daily massage
What causes toxoplasmosis in the eye?
Protozoan infection with toxoplasmosis ondii
Where can toxoplasmosis gondii be found?
Cats and raw meat
What is the disease progression of toxoplasmosis?
Mild flu like illness
Scar forming
Can reactivate
What causes toxocara and where is it found?
Parasitic nematode
Affects cats and dogs
Unable to replicate in humans
How does toxocara affect the eye?
Forms granulomas which can cause irreversible visual loss`
How are toxoplasma and toxocara diagnosed?
Serology
How is acanthamoeba diagnosed?
Microscopy/ culture
How is endophthalmitis diagnosed?
Aqueous/ vitreous humour culture
What is the mode of action of chloramphenicol?
Inhibits peptidyl transferase enzyme to stop bacterial protein
Bactericidal for strep and haemophilus
Bacteriostatic for staph
How do quinolones work?
Inhibits DNA gyrase, an enzyme that compresses bacterial DNA into supercoils
Inhibition of DNA gyrase leads to unwinding of supercoils and cell death
What bacteria can contaminate antibiotic bottles?
Pseudomonas - can cause bad corneal ulcers
What antiviral is used for dendritic ulcers?
Acyclovir which inhibits viral DNA synthesis
How is bacterial keratitis treated?
Ofloxacin (treats coliform, pseudomonas, haemophilus)
Gent and cefuroxime (treats most gram positive and gram negative organisms)
What should be taken in the history of a red eye?
Pain - grittiness, ache Itch Discharge Photophobia Visual loss Past ocular disorders Contact lenses
What can cause anterior blepharitis?
Seborrhoeic
Staphylococcal aureus
What can cause posterior blepharitis?
Meibomian gland dysfunction
What are the symptoms of seborrhoeic blepharitis?
Lid margin red
Scales
Dandruff
No ulceration, lashes unaffected
What are the symptoms of staphylococcal blepharitis?
Lid margin red Lashes distorted, loss of lashes, ingrowing lashes (trichiasis) Styes Corneal staining Marginal ulcers
What is a meibomian cyst called?
Chalazia
What is posterior blepharitis associated with?
Acne rosacea
How is blepharitis treated?
Lid hygiene
Supplementary tear drops
Oral doxycycline for 2-3 months
What can cause chronic conjunctivitis?
Blepharitis Chlamydial infection Keratoconjunctiviti sicca Lacrimal disease (chronic dacryocystitis) Glaucoma medication Sub-tarsal foregin body
What can cause peripheral corneal ulcers?
RA
Hypersensitivity
Granulomatosis with polyangitis
Polyarteritis
What are signs of anterior uveitis?
Cirilary injection Cells and flares in anterior chamber Keratic precipitates Hypopyon Synechiae
What are the symptoms of anterior uveitis?
Red eye
Dull ache
Photophobia
Referred pain to eyebrow
How is anterior uveitis managed?
Topical steroids
Mydriatics
Investigate for systemic association
What is associated with episcleritis?
Gout
What is associated with scleritis?
RA
Wegner’s
What are the signs and symptoms of scleritis?
Painful
Injection of deep vascular plexus
Phenylephrine test will show no blanching
How is scleritis treated?
Oral NSAIDs
Oral steroids
Steroid sparing agents
