Microbiology Flashcards
when is bacterial conjunctivitis a worry?
in neonates
causative organisms of neonate bacterial conjunctivitis
staph aureus
neisseria gonorrhoea
chlamydia trachomatis
causative organisms in other age groups outside neonates of bacterial conjunctivitis
staph aureus
strep pneumonia
H. influenza (especially children)
presentation of bacterial conjunctivitis
morning crust (yellow discharge)
difficulty opening eye
rapid onset
gritty eye (BUZZWORD)
diagnosis of bacterial conjunctivitis
swab
management of bacterial conjunctivitis
topical antibiotic e.g. chloramphenicol qds
fusidic acid for staph aureus
gentamicin for gram -ve
what does chloramphenicol treat?
most bacteria except pseudomonas aeruginosa
two ways of delivering chloramphenicol?
drops (need to be stored in the fridge)
ointment (difficult to see through)
when should you avoid chloramphenicol?
history of aplastic anaemia
action of chloramphenicol
inhibits peptidyl transferase enzymes (stops bacterial protein being made)
what is chloramphenicol bactericidal to?
strep
haemophilus
what is chloramphenicol bacteriostatic to?
staph
side effects of chloramphenicol
allergy
irreversible aplastic anaemia
grey baby syndrome (neonatal liver cannot cope)
what gram negatives is gentamicin used against in bacterial conjunctivitis?
coliforms
pseudomonas
what can neisseria gonorrhoeae additionally present with in bacterial conjunctivitis?
lid swelling
globe tenderness
conjunctival chemosis
this can lead to corneal ulceration and perforation (URGENT referral)
causes of viral conjunctivitis
adenovirus (pink eye)
herpes simplex
herpes zoster
presentation of viral conjunctivitis
sudden onset and rapidly progressive can be bilateral due to contagious and spreading to other eye watery pain pre-auricular nodes
what hygiene should be exercised in viral conjunctivitis?
strict hand hygiene
no sharing of towels
this is because it is highly contagious
diagnosis of viral conjunctivitis
swab
presentation of adenoviral conjunctivitis
red and inflamed eye
watery discharge (bacterial is stickier)
often history of URTI
management of adenoviral conjunctivitis
antibiotics only used if risk of secondary infection
presentation of herpes simplex conjunctivitis
vesicles on conjunctiva and eyelids
describe herpes zoster conjunctivitis
reactivation of V1, V2 and/or V3 (herpes zoster ophthalmicus)
management of herpes zoster conjunctivitis
acyclovir to minimise risk of post-hepatic neuralgia
management of viral conjunctivitis
topical lubricant e.g. hypromellose (aim for preservative free as if the patient is using this 4-6 times a day then there is risk of irritation)
acyclovir for herpes zoster
presentation of chlamydial conjunctivitis
chronic history low grade red eye follicles on inner eyelid (grains of rice) discharge pre-auricular lymphadenopathy
when to consider chlamydial conjunctivis
unresponsive to treatment
bilateral in young adults (contact tracing required)
management of chlamydial conjunctivitis
topical oxytetracycline as risk of subtarsal scarring (+ oral azithromycin if genital infection)
what to think in follicular conjunctivitis?
chlamydial conjunctivitis
presentation of allergic conjunctivitis
itch
watery
bilateral
management of allergic conjunctivitis
allergen avoidance
topical antihistamines
once stabilised use mast cell stabilisers e.g. sodium cromoglycate
define episcleritis
inflammation of the thin vascular sheet between the conjunctiva and sclera
who is episcleritis common in?
patients with collagen-vascular disease such as RA, sarcoidosis and IBD
management of episcleritis
NSAIDs
topical lubricants
define acute anterior uveitis (iridocyclitis)
inflammation of the iris and ciliary body
presentation of acute anterior uveitis (iridocyclitis)
sudden onset of pain (can radiate to brow and exacerbated by focusing on a near object)
red eye and hyperaemia at limbus
photophobia (BUZZWORD)
smaller pupil, ptosis due to local tissue swelling
blurred vision
if significant inflammation then a hypopyon can form
what to do if it is a first presentation of acute anterior uveitis (iridocyclitis)
refer
what is acute anterior uveitis (iridocyclitis) linked to?
HLA-B27 (if multiple presentations do AI screen)
management of acute anterior uveitis (iridocyclitis)
mydriatics (cycloplegia e.g. cyclopentolate hydrochloride)= dilates pupil reducing risk of it getting stuck to the eye
steroids e.g. dexamethasone to reduce inflammation
define blepharitis
inflammation of eyelids, usually a chronic condition affecting both eyes
presentation of blepharitis
redness around eyelid margins
patients complain of gritty eyes
why should bacterial keratitis be referred?
it eats the eyeball and can cause perforation
define keratitis
infection of the cornea
presentation of bacterial keratitis
loss of clear appearance
hypopyon
what is bacterial keratitis associated with?
other corneal pathology
wearing contacts lenses (swimming or sleeping)
diagnosis of bacterial keratitis
corneal scrap for microscopy
management of bacterial keratitis
hourly drops (including at night so may need to admit)
examples of drops used in bacterial keratitis
- 4-quinolone (oflaxacin)= gram -ve including coliforms, pseudomonas and H. influenza
- gentamicin and cefuroxime= gram +ve and -ve
what can UVB exposure cause?
keratitis
causes of viral keratitis
herpes (HSV)
adenovirus
what does hepatic keratitis present with?
dendritic ulcer (branching)
diagnosis of hepatic keratitis?
fluorescence to show missing epithelium where virus is
presentation of hepatic keratitis
pain
recurrence can lead to reduced corneal sensation (vision)
management of hepatic keratitis
must use steroids with acyclovir/ ganciclovir as can cause corneal melt and perforation
can use topical anaesthetic for examination but do not repeat as toxic
presentation of adenoviral keratitis
bilateral
follows URTI
contagious
can affect vision
management of adenoviral keratitis
topical antibiotics only to prevent secondary infection
steroids to tame immune reaction
fungal keratitis causes
acanthamoeba (pseudomonas aeruginosa)
moraxella
what is fungal keratitis associated with?
wearing contacts
younger patients
chronic history
those who work outside
presentation of fungal keratitis
extreme pain
more defined hypopyon
diagnosis of fungal keratitis
culture of contact lens and microscopy
management of fungal keratitis
urgent referral
topical anti-fungal e.g. natamycin
define orbital cellulitis
pus in the orbit
what can orbital cellulitis lead to?
can lead to compartment syndrome and proptosis
presentation of orbital cellulitis
pain, especially on eye movements as muscle are close to inflammation
paranasal sinusitis (ethmoid)
pyrexia
history of URTI
well demarcated erythema around the orbit
diagnosis of orbital cellulitis
CT to show orbital abscesses
secondary causes of orbital cellulitis
infected chalazion (cyst on eyelid due to blocked duct) dacryocystitis
two types of orbital cellulitis
pre-septal (compresses optic nerve)
orbital (does not compress optic nerve)
causative organisms in orbital cellulitis
large spectrum of microorganisms so manage with broad spectrum antibiotics
management of orbital cellulitis
broad spectrum antibiotics
abscess may require drainage
define endophthalmitis
infection of the inside of the eye
cause of endophthalmitis
almost always post surgery (return 2-3 days after with pain)
endogenous (septicaemia)
presentation of endophthalmitis
pain
decreasing vision (lost in 48 hours and irreversible)
very red eye
causative organisms of endophthalmitis
commensals e.g. staph epidermidis
diagnosis of endophthalmitis
aqueous/vitreous for culture
management of endophthalmitis
antibiotic injections into vitreous under LA (amikain/ceftazidime/ vancomycin)
topical antibiotics
systemic antibiotics
define chorioretinitis
inflammation of the choroid and retina
cause of chorioretinitis in AIDS
CMV
cause of chorioretinitis in immunosuppressed
HSV (or when run down/tired)
two parasitic causes of chorioretinitis
toxoplasmosis toxocara canis (worms)
where does toxoplasmosis come from?
cats
raw meat
mother to foetus (IgG)
presentation of toxoplasmosis
flu-like illness
cyst forming
macula scarred
reactivation in later life can affect vision
what do you get toxocara canis from?
cats
dogs
describe toxocara canis
unable to replicate so remains as larvae
reactivate and produce granulomas
diagnosis of parasitic choriretinitis
serology
define dacrocystitis
stagnation of the drainage of the lacrimal duct
what does dacrocystitis lead to?
occlusion of the sac causing swelling due to excess fluid and a secondary infection
management of dacrocystitis
penicillin
