Microbiology & the eye Flashcards
What is inflammation of the entire globe called?
Endophthalmitis
What are the common causes of bacterial conjunctivitis in neonates?
Staph. aureus
Neisseria gonohhoeae
Chylamydia trachometis
What are the most common causative organisms in bacterial conjunctivitis in not neonates?
Staph. aureua
Strep. pneumoniae
Haem. influenzae (esp. children)
Treatment of bacterial conjunctivitis
Usually self limiting but if needed cholramphenicol
When should chloramphenicol be avoid?
History of aplastic anaemia or allergy
How is viral conjunctivitis different from bacterial clinically?
Watery rather than mucousy discharge
How does a viral conjunctivitis usually present?
Usually starts with URTI
Watery discharge
Causes of viral conjunctivities
Adenovirus
Herpes Simplex
Herpes zoster
What is Hutchin-Robinsons sign?
Sports on end of nose - Herpes zoster infection of trigeminal nerve (virus sits in ganglion then comes out at times of stress)
When should chlamydial conjunctivitis be suspected?
Bilateral conjunctivitis in young adults
What other symptoms may accompany chlamydial conjunctivitis?
Urethritis
Vaginitis
What is bacterial keratitis usually associated with?
Other corneal pathology or conact lens wear
Management of bacterial keratitis
Need admission for hourly drop
What is a hypopyon?
White blood cells & inflammatory material in anterior chamber
Typical presentation of bacterial keratitis with hypopyon?
Painful
Reduced vision
White mark in red eye (URGENT!!)
What 2 virus most commonly cause keratitis?
Herpes simplex
Adenoviral
Presentation of herpetic keratitis
Very painful
Can be recurrnt
Recurrences eventually result in reduced corneal sensation
Why should herpetic keratitis not be treated with steroids?
Can cause corneal melt and perforation of the cornea
Presentation of adenoviral keratitis?
Bilateral
Following URTI
Contagious
May affect vision
Management of adeoviral keratitis
May be given topical AB to prevent secondary bacteria infection
What keratitis is associated with washing lenses in ta water?
Acanthamoeba
Typical features of pseudomonas aeruginosa keratitis
Farmers/gardeners
In eyes that have other problems
Takes a long time to heal
Presentation of orbital cellulitis
Painful (especiialy on eye movements)
Proptosis
Often associated with paranasal sinusitis
Pyrexial
First line investigation in suspected orbital cellulitis
CT scan
What is dacrocystitis?
Infection of the lacrimal sac
Organisms that cause orbital cellulitis
Staphylococci Streptococci Coliforms Haem. influenzae Anaerobes
What is endophthalmitis?
Devastating infection inside the eye usually due to blunt trauma
Presentation of endophthalmitis
Painful ++++
Decreasing vision
Very red eye
Organisms that cause endophthalmitis
Often conjunctival “commensals”
Most common is staph epidermis
Treatment of endopthalmitis
Intravitreal amillacin and vancomysin and topical antibiotics
What virus causes chlororetinitis in AIDs patients?
CMV
What rotozoan infection causes chlororetinitis?
Toxoplasma gondil
Treatment of toxoplasma gondil
Self limiting but would want to treat if close to disc
What parasitic infection can cause chlororetinitis?
Toxocara canis (worm)
Are toxocara canis able to replicate in humans?
No
Why could toxocara be sight threatening?
Can form granulomas
How is enophthalmitis diagnosed?
Aqueous/vitreous cultue
How is acanthamoeba diagnosed?
Microscopy/culture
How is bacterial keratitis diagnosed?
Corneal scrape
What are the 3 types of swab?
Bacterial
Chlamydial
Viral
What is the mechanism of action of chloramphenicol?
Inhibits peptidyl transferase enzyme (sops bacterial protein being made)
Side effects of cholramphenicol
Allergy
Irreversible aplastic anaemia
Grey baby syndrome
When is the site of action of penicillins?
Bacterial cell wall
What is a common contaminant of eye drop bottles?
Pseudomonas
What problems can be caused by pseudomonas contaminant?
Corneal ulcer
Which bacteria is not treated by cholramphenicol?
Pseudomonas aeruginosa
Which bacteria does fusidic acid treat?
Staph aureus
What could treat bacterial onjunctivitis caused by pseudomonas aeruginosa??
Gentamicin
What is the management for chylamidial conjuntivtiis?
Topical oxytetracycline
First line treatment for bacterial keratitis
Ofloxacin
What bacteria does ofloxacin not treat?
Strep. pneumoniae
