Microbiology in Ophthalmology Flashcards
what are common infecting organisms in neonatal bacterial conjunctivitis?
Staph aureus
niesseria gonorrhoea
chlamydia trachomatis
True / False
all neonatal cases of bacterial conjunctivitis should be referred to ophthalmology?
True
What is a common infecting organism of bacterial conjunctivitis in children?
Haemophilus influenzae
What are some common infecting organisms in bacterial conjunctivitis?
Staph aureus
Strep pneumoniae
Haemophilus influenzae
How is bacterial conjunctivitis treated?
Swab
Topical antibiotic usually chloramphenicol drops or ointment
When should Chloramphenicol be avoided?
in aplastic anaemia
What is the difference between bacterial and viral conjunctivitis?
Bacterial conjunctivitis produces a sticky discharge whereas viral conjunctivitis produces a watery discharge
What are the common viral agents causing viral conjunctivitis?
Adenovirus
herpes simplex
herpes zoster
In what type of conjunctivitis is there often a chronic history?
Chlamydial conjunctivitis
In who and how does Chlamydial conjunctivitis often present?
bilaterally in young adults
What can Chlamydial conjunctivitis cause?
sub tarsal scaring
Where should microbial keratitis be treated?
in a hospital setting - can be sight threatening
how does microbial keratitis present?
red eyes and corneal ulcers
What is microbial keratitis associated with?
contact lens wearers
patients with another corneal pathology
How is microbial keratitis diagnosed?
corneal scrape under anaesthetic
what is typically seen in herpetic keratitis?
dendritic ulcer
very painful
Why should herpetic keratitis not be treated with steroids?
can cause a corneal melt and perforation of the cornea
What is the history and presentation of adenoviral keratitis?
subepithelial infiltrates
bilateral
usually following a URTI
how is adenoviral keratitis treated?
with topical steroids to prevent secondary infection
can require steroids if chronic
What is fungal keratitis often associated with?
history of trauma from vegetation
What is the treatment of bacterial keratitis
A 4-quinolone (ofloxacin) -not active against strep. pneumoniae
Gentamicin and cefuroxime (will treat most gram +ve and -ve bacteria)
What are the symptoms of orbital cellulitis?
painful - especially on eye movemetns
proptosis
pyrexia
What is orbital cellulitis often associated with?
paranasal sinusitis
What investigation is done in orbital cellulitis?
CT scan - identity orbital abscesses
What are common infecting organisms in orbital cellulitis?
Staphylococci Streptococci Coliforms Haemophilus influenzae anaerobes
What is the treatment for orbital cellulitis?
broad spectrum antibiotics
close monitoring
drainage of abscess
What is endophthalmitis?
infection inside of the eye
how does endophthalmitis present?
very painful
decreasing vision
very red eye
sight threatening
What causes endophthalmitis?
often conjunctival commensals following a surgical procedure
What is the most common infecting organism in endophthalmitis
most common is staph epidermis - conjunctival commensal
What is the treatment for endophthalmitis?
Intravitreal amikacin and vancomycin and topical antibiotics
What are the common infecting organisms in Chorioretinitis
CMV in AIDs
Toxoplasma gondii
Toxocara canis (worm)
what causes toxoplasmosis?
tics
How does toxoplasmosis present?
mild flu like symptoms
What type of treatment is given in toxoplasmosis? why?
systemic - sight threatening
In bacterial, chalmydial and viral eye infection how is diagnosis made?
swabs for culture
in bacterial keratitis how is diagnosis made?
corneal scrape under anaesthetic
How is a diagnosis of endophthalmitis made?
Aqueous/vitreous for culture
how is diagnosis of Chorioretinitis
made?
serology for toxoplasma / toxocara
What is toxocara associated with?
cats and dogs
what is the mechanism of Chloramphenicol?
- Inhibits peptidyl transferase enzyme (therefore stops bacterial protein being made)
- Bacterocidal for strep and haemophilus
- Bacterostatic for staph
What are side effects of Chloramphenicol?
allergy
irreversible aplastic anaemia
grey baby syndrome
how do penicillins and cephalosporins work?
• B lactam ring inhibits enzyme which makes bacterial cell wall
• Without cell wall, bacteria die
bactericidal
give an example of a quinolone
ofloxacin
how do quinolones work?
- inhibit DNA gyrase, an enzyme that compresses bacterial DNA into supercoils
- Inhibition of DNA gyrase leads to unwinding of supercoils and cell death
what organism is a common contaminant of eyedrops?
pseudomonas
What drug is given for dendritic ulcers of the cornea?
acyclovir
NOT STEROIDS - CORNEAL MELT
what drugs can be given in bacterial conjunctivitis?
Chloramphenicol
Fusidic acid
gentamicin
What is Chloramphenicol effective against?
most bacteria except Pseudomonas aeruginosa
what microorganism is fusidic acid effective against?
staph aureus
What is gentamicin effective against?
most gram negative bacteria including coliform and pseudomonas aeruginosa
what treatment is given for chlamydial conjunctivitis?
topical oxytetracycline oral azithromycin (if genital infection also present)
