Microbiology Flashcards
name the types of gram positive cocci
strep and staph
what are the types of gram negative bacteria
cocci (e.g. neisseria)
cocci-bacilli (H. influenzae)
bacilli (pseudomonas)
what is an infection of the cornea called
keratitis
what is an infection of the entire globe called
endophthalmitis
when do you always refer bacterial conjunctivitis
when it affects a neonate (under 2 weeks)
what organisms can cause bacterial conjunctivitis in neonates
staph aureus
neisseria gonorrhoeae
chlamydia trachomatis
what organisms commonly cause bacterial conjunctivitis
staph aureus, strep pneumoniae, haemophilus influenzae
what organism commonly causes bacterial conjunctivitis in children
haemophilus influenzae
how do you treat bacterial conjunctivitis
swab topical antibiotic (chloramphenical) drops/ ointment
when do you not give chloramphenicol
if history of aplastic anaemia or allergy
when should you be suspicious of a cholramphenical allergy
is symptoms of bacterial conjunctivitis get worse (redder and itchy)
what commonly causes viral conjunctivitis
adenovirus, herpes simplex, herpes zoster
what is the difference in presentations of bacterial and adenoviral conjunctivitis
viral wont usually have discharge
what is the treatment for adenovirus conjunctivitis
usually self limiting
what is the presentation of herpes simplex conjunctivitis
can get vesicle around eye
what is the presentation of herpes zoster conjunctivitis
shingles of the ophthalamic trigeminal nerve
vesicles in dermatome
(aka herpes zoster ophthalmicus)
what is the usual presentation of chlamydial conjunctivits
often chronic- conjunctivitis that doesnt respond to topical antibiotics
suspect it in bilateral conjuctivitis in young adults
may have symptoms of urethritis, vaginitis
what is the appearance of chlamydia conjunctivitis
follicular, grains of rice appearance under the lid
what does the folliclular appearance of chlamydial conjunctivitis cause
subtarsal scarring (damage to the cornea)
what is the outer lining of the cornea continuous with
the conjunctivia
what is a hypopyon
leukocytic exudate in the anterior chamber of the eye (within cornea)
what is a hypopyon seen in
keratitis- very serious, sight threatening
what is the treatment for bacterial keratitis
need admitted for hourly drops and daily review
what is bacterial keratitis usually seen with
other corneal pathology or contact lens wear
what us a corneal ulcer
keratitis
what viruses cause microbial keratitis
herpes and adenovirus
can viral keratitis happen in a normal eye
yes, unlike bacterial keratitis
what do you get dendritic ulcers in
herpetic keratitis (looks like a branching tree) (caused by herpes simplex)
what are the features of herpetic keratitis
dendritic ulcer
very painful
recurrent (can cause reduced corneal senation, scarring)
can you treat herpetic keratitis with steroid
NO can cause corneal to melt and perforate
what are the features of adenovirus keratitis
supepithelial infiltrates, almost always with conjunctivitis, bilateral, usually follow URTI, contagious, may affect vision
what is the treatment for adenoviral keratitis
topical AB to prevent secondary infection, can give mild steroids to speed up recovery if it becomes chronic
what can cause fungal keratitis
acanthamoeba, pseudomonas aeruginosa
what is the usual presentation of fungal keratitis
infection caused by contact lenses or in farmers or gardeners after trauma, painful, scarring, very hard to treat, takes long time to heal
what is the presentation of orbital cellulitis
painful- especially on eye movement proptosis often with paranasal sinusitis pyrexial sight threatening
what is the risk with orbital cellulitis
compartment syndrome due to pus behind eye, can compromise eye circulation
what can cause orbital cellulitis
extension from focal orbital infection, post operative
what is the most worrying type of orbital cellulitis
orbital
preseptal cant cause compartment syndrome
what organisms cause cause orbital cellulitis
staph, strep, coliforms, h. influenzae (children), anaerobes
when do you CT scan in orbital cellulitis
if there is any suggestion of muscles or optic nerve dysfunction
how do you treat orbital cellulitis
broad spectrum AB, monitor closely, maybe need drainage
what is first to go when optic nerve is compromised
colour vision- red
what is endophthalmitis
devasting infection inside of the eye, very rare
what causes endophthalmitis
post surgical, endogenous (e.g. bacterial endocarditis)
often conjunctival commensals- staph epidermis
what is the presentation of endophthalmitis
very painful, decreasing vision, sight threatening
what is the treatment for endophthalmitis
Intravitreal amikacin/ ceftazidime/ vancomycin and topical antibiotics
inject AB after surgery as prophylaxis
what is chorioretinitis
infection of the choroid
what are the causes of chorioretinitis
CMV in AIDS toxoplasma gondii (protozoan) toxocara canis (worm)
where do you get toxoplasma gondii
cats and raw meat
what is the presentation of toxoplasma gondii chorioretinitis
Mild flu like illness
Rarely causes any further problems
In immunocompetent patients it enters latent phase with cysts forming
can reactivate, needs systemic treatment if life threatening
where is Toxocara canis (worm) found
cats and dogs
unable to replicate in humans so self limiting
is Toxocara canis (worm) choriorentinitis bad
self limiting but can form granulomas which can cause irreversible visual loss
when do you do a corneal scrape
in baterial keratitis (bacterial ulcer)
how do you diagnose endophthalmitis
aqueous/ vitreous for culture
how do you diagnose acanthamoeba
microscopy/ culture
when do you serology
if suspect toxoplasma or toxocara (choriodrentinitis)
how can you give chloramphenicol
drops (4x per day, has to be kept in fridge) or ointment (had to use)
how does chloramphenicol work
Inhibits peptidyl transferase enzyme (therefore stops bacterial protein being made)
what does chloramphenicol work against
Bacterocidal for strep and haemophilus
Bacterostatic for staph
what are the side affects of chloramphenicol
allergy, aplastic anaemia, grey baby syndrome (when give too much to babies they go grey, reduce dsose)
what are antibiotics than inhibit cell wall synthesis
Penicillins & cephalosporins (have B lactam ring)
what is dacrocystitis
when lacrimal sac becomes infected
what are antibiotics that inhibit nucleic acid synthesis
Quinolones
what antibiotic for corneal ulcers
quinolones
what are the antibiotics ffor bacterial conjunctivitis
chloramphenicol
(treats most bacteria except Pseudomonas aeruginosa)
fusidic acid
(treats Staph. aureus)
gentamicin
(treats most Gram negative bacteria including coliforms, Pseudomonas aeruginosa)
what treatment for herpetic ulcers
aciclovir
how do you treat chlamydial conjunctivitis
topical oxytetracycline
how do you treat bacterial keratitis
A 4-quinolone (Ofloxacin)
(treats most Gram negative bacteria including coliforms, Pseudomonas aeruginosa, Haemophilus influenzae. Not active vs. Strep. pneumoniae)
Gentamicin and cefuroxime
(the combination will treat most Gram positive and Gram negative organisms)
