Microbiology Flashcards
chemical properties of the eye to prevent infection
lysozyme to destroy bacterial cell walls
lipids and IgA to prevent attachment
interleukins to allow immune regulation
physical features of the blink reflex to prevent infection
tears flush dirt and bacteria from eye
mucus layer on top of cornea as anti-adhesive
what function does the langerhans cell have in immune regulation within the eye and where is it present
principle APC for external eye
corneo-scleral limbus and in peripheral cornea
absent from central cornea
what is the only part of the eye with lymphatic drainage
conjunctiva
describe immune properties of the conjunctiva for fighting infection
dendritic cells, langerhans
travel to MALT if required
mast cells, macrophages and langerhans are all present in MALT
describe immune properties of the sclera and cornea for fighting infection
no lymphatics or MALT
lack of APC
langerhans is present in the peripheral cornea
downregulated environment
describe the immune properties of the lacrimal gland and drainage system
plasma cells secreting IgA and CD8+T cells in small groups
resting lymphoid cells rare
diffuse MALT in the drainage system
describe immune privilege and sites that may have it
placenta and foetus eye brain testes can tolerate introduction of antigens without eliciting inflammatory immune response
what properties allow the eye to have immune privilege
blood tissue barrier
lack of lymphoid drainage
immune suppressive molecules
what is symptathetic ophthalmia
rare and bilateral uveitis due to trauma/surgery to one eye
AA reaction to ocular antigens due to event
immune response at elevated rate with CD4/CD8 T cells
these are activated by antigens and respond to the antigens in both eyes
sympathetic ophthalmia - injured eye is the exciting/sympathising eye and the other is the exciting/sympathising eye
injured is exciting
other is sympathising
how can you tell the exciting and sympathising eye apart in sympathetic ophthalmia
the history alone
what is ocular cicatrical pemphigoid
blistering autoimmune conjunctavitis leading to scarring
can lead to adhesions of conjunctiva and sclera leading to ectropia
manage with high dose steroids
example of type 3 sensitivity to eye
autoimmune corneal melt
example of a type 4 hypersensitivity to eye
corneal graft rejection
what causes corneal graft rejection
vascularisation of host cornea reaching donor tissue and leading to immune response
factors of immune privilege that prevent corneal graft rejection
reduced MCH I/II
lack of blood and lymph supply to cornea
central cornea deficient in langerhans cells
immunosuppressive molecules and inhibition of immune mediators
side effects of steroid therapy on the eye?
steroid induced glaucoma
cataracts
bacteria in neonatal bacterial conjunctavitis?
MUST refer
n gonorrhoeae
staph aureus
chlamydia
bacteria in child/adult bacterial conjunctavitis
h influenzae in children
staph aureus
strep pneumoniae
management of bacterial conjunctavitis?
swab
topical abx - chloramphenicol drop/ointment 4 daily
side effects/contraindication chloramphenicol?
allergy, aplastic anaemia
worsening symptoms may mean allergy
microbes in viral conjunctavitis
adenovirus - following URTI
herpes simplex
herpes zoster
presentation of viral conjunctivitis
red eye, profuse watering
hutchisons sign in shingles
presentation of bacterial keratitis
whitening of cornea
hypopyon
who is more likely to get bacterial keratitis
people with other eye pathologies or contact lens wearers
management of bacterial keratitis
admit hourly eye drops daily review local anaesthetic, removal, swab can lead to cornea rupture
how may viral keratitis be managed
ganiclovir
do not treat with steroids as may lead to corneal melt
presentation of herpes viral keratitis
little vesicles round eye and maxilla
painful
dendritic appearance on stain
presentation of adenovirus viral keratitis
dimples, reduced vision
painful
bilateral
may follow URTI or conjunctivitis
in who is fungal keratitis more common and how is it treated
ocular surface disease, those who work outside
defined corneal lesions
anti-fungals
what is acanthomoeba
parasite specific to contact lens wearers
usually due to rinsing contacts under tap water
ring like deposit on cornea
culture contact lenses
presentation of preseptal cellulitis and management
shiny, red tight around eyelid
fluclox usually settles, may be needed systemic
presentation of orbital cellulitis
pain, esp on eye movement
proptosis
involvement with paranasal sinuses
pyrexia
treatment of orbital cellulitis
broad spec systemic abx
drainage of abscesses
CT scanning
organisms in orbital cellulitis
staph/strep
coliforms
h influenzae
anaerobes
diagnosis of orbital cellulitis
CT urgent
visual function
redness of entire orbital wall
hx
what is endopthalmitis and what causes it
devastating infection in inside of eye
sight threatening
post surgical/endogenous
presentation of endopthalmitis
highly painful and red eye with decreasing vision
management of endopthalmitis
intra-vitreal abx directly
sample then take abx
topical bx
systemic abx dont do much
management of CMV chorioretinitis and what causes it
HIV/AIDS
intra-vitreal antiviral drugs
what viruses can lead to acute retinal necrosis
HSV/HZV
presentation of toxoplasma chorioretinitis, where is it caught
mild flu like illness
congenital or acquired from contaminated soil, undercooked meat
how may toxoplasma/toxocara cause retinal issues
may lead to retinal scarring and may be incidental
can reactivate
how is toxoplasma causing sight threatening damage managed
systemic clidamycin/azithromycin with steroids
cause of candida chorioretinitis
endocarditis, indwelling catheters, central lines
what are swabs suited for in eye infection
bacteria
viruses
chamydia
what are corneal scrapes suited for in eye infection
fungi
what are aqueous/vitreous cultures indicated for
endopthalmitis
what is serology in eye infection indicated for
toxoplasma/toxocara
what is microscopy and culture indicated for in eye infection
acanthomoeba
management of chlamydial conjunctavitis
topical oxytetracycline
how does chloramphenicol work and side effects
inhibits bacterial peptidyl transferase
irreversible aplastic anaemia, grey baby syndrome, allergy
how do quinolones work, what are they and what do they treat
inhibit gyrase
gentamicin, cefuroxime
treat most gram -ves, coliforms and pseudomonas
what are the issues from storing eye drop bottles with preservatives
can contaminate to culture pseudomonas
indication for ganiclovir and how does it work
inhibits viral DNA synthesis
dendritic ulcers of cornea
