Microbiology Flashcards
What is an infection of the cornea?
Keratitis
What is infection of the entire globe?
Endophthalmitis
What organisms can cause conjunctivitis in neonates?
Staph aureus
Neisseria gonorrhoeae
Chlamydia trachomatis
What are conjunctivitis causes at other ages?
Staph aureus
Strep pneumoniae
Haemophilus influenza (esp. in children)
How do you treat bacterial conjunctivitis?
Swab
Topical antibiotics
Drops vs ointments
When should you avoid chloramphenicol?
History of aplastic anamia or allergy
What are viral causes of conjunctivitis?
Adenovirus
Herpes simplex
herpes zoster
What are signs of chlamydial conjunctivitis?
Chronic history
unresponsive to treatment
symptoms of urethritis and vaginitis
What is involved in Hutchison & Robinson sign?
Tip of the nose
What is a hypopyon?
A greeny yellow dot in the eye
What is the treatment for bacterial keratitis?
Admission for hourly drops
Daily review
Assoc. with corneal pathology or contact lens wear
What are viral causes of karatitis?
Herpes
Adenovirus
Describe herpetic karatitis
Painful
Recurrent
Reduced corneal sensation
steroids can cause corneal melt and perforation
Describe adenovirus keratitis
Bilateral Follows URTI Contagious Topical AB to prevent secondary infection May affect vision Can give steroids
What are fungal causes of karatitis?
Acanthamoeba
Pseudomonas aeruginosa
Describe fungal karatits
More idolent than bacterial
History of trauma from vegetation
Long time to heal
Describe orbital cellulitis
Painful - esp on eye movement Assoc. paranasal sinisitus Pyrexial Sight threatening cared by ENT and optha CT scan for orbital abscesses
Where does orbital cellulitis extend from?
Directly from sinus
From focal orbital infection
Post operative
What organisms can cause cellulitis?
Staphylococci Streptococci Coliforms Haemophilus influenzae anaerobes
What is endophthalmitis?
infection inside the eye
very painful with decreased vision
red eye
post surgical or endogenous
What is the most common cause of endophthalmitis?
Staph epidermidis
What is used to treat endophthalmitis?
Intravitreal amikacin and vancomycin
Topical antibiotics
What organisms cause chorioretinitis?
CMV in AIDS
Toxoplasma gondii
Toxocara canis (worm)
What is toxoplasmosis?
Protozoan infection flu-like if immunosuppressed, cysts may form IgG Can reactivate
Describe toxocara
Parasitic nemotode
affects cats/dogs
cant replicate in humans
Form granulomas which can cause irreversible visual loss
How do you diagnose an eye infection?
Swabs Corneal scrapping aqueous/vitreous for culture microscopy/culture serology
What 3 things can broad antibiotics do?
Inhibit protein synthesis
Inhibit cell wall synthesis
Inhibit nucleic acid synthesis
Describe chloramphenicol
ointment/drops
inhibits peptidyl transferase enzyme
Bacteriocidal for strep/heamophilus
Bacteriostatic for staph
What side effect can chloramphenicol?
Grey baby syndrome
What AB inhibit cell wall synthesis?
Penicillins and cephalosporins have common B lactam ring
What AB inhibit nucleic acid synthesis?
Quinolones e.g.ofloxacin
inhibit DNA gyrase
What antiviral inhibits viral DNA synthesis?
Aciclovir
Antivirals used for dendritic ulcers of corneas
Dont give steroids
How do you treat bacterial conjunctivitis?
Chloramphenicol
Fusidic acid
Gentamicin
What does chloramphenicol treat against?
Bacteria except pseudomonas aeruginosa
What does fusidic acid treat against?
staph aureus
What does gentamicin treat against?
Gram negative bacteria including coliforms, pseudomonas aeruginosa
What is used to treat chlamydial conjunctivitis?
topical oxytetracycline
adults may beed oral azithromycin
What is used to treat bacterial keratitis?
A 4-quinolone (Ofloxacin)
Gentamicin and cefuroxime
What does A 4-quinolone (Olfoxacin) treat against?
Gram negative bacteria but not strep pneumoniae
What does Gentamicin and cefuroxime act against?
gram positive and gram negative organisms when used together
