Microbiology Flashcards
What is the term for inflammation of the conjunctiva?
Conjunctivitis
What is the term for inflammation of the cornea?
Keratitis
What is the term for inflammation of the entire globe (orbit etc.)
Endophthalmitis
What are the common pathogens for neonatal bacterial conjunctivitis?
Staph aureus
Neisseria gonorrhoea
Chlamydia trachomatis
When would a neonatal conjunctivitis case be referred to ophthalmology?
Always
What is the commonest bacterial cause of conjunctivitis in children?
Haemophilus influenzae
What are the common bacteria causing conjunctivitis in adults?
Staph aureus
Strep pneumoniae
What antibiotic is typically used for bacterial conjunctivitis?
Topical chloramphenical
Unless history of aplastic anaemia it allergy
What are the main viral causes of conjunctivitis?
Adenovirus
Herpes simplex
Herpes zoster
What should you suspect when a young adult presents with bilateral conjunctivitis?
Chlamydia conjunctivitis
What can a sign of progressive chlamydial conjunctivitis be?
Subtarsal scarring
What is the physical description of an eye with bacterial keratosis?
Red eye
Reduced vision
White lesion in cornea (sits at the bottom +/- patch over central iris)
What is the pathophysiology of white lesions in the cornea?
The usually very organised collagen fibres in the cornea have been disturbed by the bacterial infiltration
What is the treatment plan for people with bacteria keratitis?
Admission for 48 hours - hourly eye drops
What typically gives you clues towards a diagnosis of bacterial keratitis?
Other corneal pathology
Contact lens wearers
What keratitis is more likely to occur in someone with a previously non-pathological cornea?
Viral kerititis
What is the sign of herpetic keratitis?
Dendritic ulcers
What is unfortunate about having a herpetic keratitis?
It is very painful
It can be recurrent
And recurrence can cause eventual reduced corneal sensation
Higher risk of developing bacterial keratitis
What must you never treat herpetic keratitis with?
Steroids
What is a typical sign of adenoviral keratitis?
Subepithelial infiltrates
What pathologies are associated with adenoviral keratitis?
Conjunctivitis
Respiratory infection
Are adenoviral keratitis infections bilateral or unilateral?
Bilateral
Are adenoviral keratitis infections contagious?
YES
What would you prescribe to treat adenoviral keratitis?
Topical antibody- prevent secondary infection
Steroids to speed up recovery (if condition chronic)- BUT ONLY IF CERTAIN IT ISN’T HERPETIC KERATITIS
What is the likely pathogens for keratitis caused by washing contact lenses in tap water?
Acanthamoeba
Pseudomonas aeruginosa
What would the causative pathogen for a keratitis resulting from a trauma associated with vegetation be?
Fungal pathogen
What would you treat fungal keratitis with?
Have to try different things as very difficult and long healing process
Often need corneal grafts
What is the typical presentation of an orbital cellulitis?
Extremely painful (especially on eye movements)
Associated Paranasal sinusitis
Pyrexia
Proptisis (protruding eye)
Why would you CT someone with orbital cellulitis?
To check for and identify orbital abscesses
What is the most common cause of orbital cellulitis?
Infection from skin commensals post operatively
What must you differentiate orbital cellulitis from?
Preseptal cellulitis (when it’s just the outer surface of the skin- should have no altered structure and function of the eye)
What are the organisms that can cause orbital cellulitis?
Staphylococci (epi/aureus) Streptococci California Haemophilus influenzae Anaerobes
What would you do to manage orbital cellulitis?
Examine routinely to check for restriction of muscles or optic nerve dysfunction (CT scan if so)
Broad spectrum antibiotics and close monitoring
Possibly drain abscesses
What is the rarest and most devastating eye infection?
And what often the cause
Endophthalmititis
Post surgical infection
What are some endogenous causes of endophthalmitis?
Bacterial endocarditis etc.
What does endophthalmitis present as?
Very red eye
Extremely painful
Decreasing vision
What is the most common organism causing endophthalmitis?
Staph epidermidis
How do you treat endophthalmitis?
Intravitreal (inside posterior eye) amakacin/ceftazidime/vancomycin
Topical antibiotics
Possible systemic antibiotics
What are causes of chorioretinitis?
Cytomegalovirus in AIDS (much rarer now)
Toxoplasma Gondi
Tococara canis (worm)
What was a previously common ocular presentation of aids?
Haemorrhagic cytomegalovirus retinitis
Where might a person contract toxoplasmosis?
Cats
Raw meat
What does toxoplasmosis present as?
Mild flu-like illness
In the immunocompromised- latent phase with cyst formation
Is toxoplasmosis recurrent?
Yes in the immunocompromised
Can the toxocara worm replicate in humans?
And what damage does it do?
No, but it lives as an immature larvae form of the worm
It forms granulomas—> lead to irreversible visual loss
How do you diagnose and eye infection?
Swan for culture (bacterial, chlamydial, viral)
Corneal scrapes (bacterial keratitis)
Aqueous/vitreal humour for culture (endophthalmitis)
Microscopy/culture for acanthamoeba (of contact lenses too)
Serology (toxoplasma, toxocara)
What is the most common topical antibiotic for eye infections?
Chloramphenicol
How does chloramphenicol work?
Inhibits peptides transferase enzyme (prevents bacterial protein synthesis)
Kills strep and haemophilus
Slows down staph
What are chloramphenicol’s side effects?
Allergy
Irreversible aplastic anaemia
Grey baby syndrome
What is a common bottle contaminant?
Pseudomonas
Dispose of bottles after 4 weeks
What can psueudomonas cause in the eye?
Ulcers
What would you treat a staph aureus conjunctivitis with?
Fusidic acid
What would you treat most conjunctivitis infections with?
Chloramphenicol
What would you treat a gram negative conjunctivitis with?
Gentimicin
What antiviral can be used for viral keratitis?
Aciclovir
What do you treat chlamydial conjunctivitis with?
Topical oxytetracycline
Oral azithromycin if genital chlamydia too
What would you treat keratitis caused by gram negative, pseudomonas areuginosa, haemophilus influenzae?
Ofloxavcin (4-quinolone)
What would you treat a keratitis caused by most gram positive/negative organisms?
Gentamicin and cefuroxime
