Bacteriology 1&2 Flashcards
Defense mechanisms of the eye (2)
1) Normal Flora
2) Tears and blinking
How does normal flora help prevent eye infections (2)
1) Primarily Gram + bacteria present at low numbers
2) limit the ability of pathogens to attach & cause disease
How do tears and blinking help prevent eye infections (2)
1) Rinse ocular surface
2) Contain antibacterial substances (IgA, Lysozyme and lactoferrin)
Predisposing risk factors for extraocular infections (6)
1) most extra cellular infections are secondary
2) Trauma
3) Infections in adjacent structures
4) Drying of cornea
5) Immunosupression
6) Co-infection w/ other organs
Predisposing risk factors for intraocular infections (3)
1) most are secondary
2) often ocular manifestations of systemic infections or disease
3) Some intraocular infections result from direct inoculation
Mechanisms of damage of pathogens (4)
1) Adhere
2) Invade Tissues
3) Evade host defense mechanisms
4) cause host cell damage
Extraocular Infections (7)
1) blepharitis
2) conjunctivitis
3) keratitis
4) keratoconjunctivitis
5) fungal infections
6) viral keratitis/conjunctivitis
7) viral corneal edema
Causes for blepharitis (6)
1) Gram + cocci
2) S. pseudintermedius, B. hemolytic streptococci, S. canis, S. zooepidemicus
3) dermatophytes
4) cuterebra larvae
5) sarcoptes
6) demodex
Cause of conjunctivitis (3)
1)Chlamydia felis
2) Mycoplasma spp.
3) Pasturella multocida
Chlamydia felis (4)
1) Young cats
2) act alone or coinfection with feline herpes, mycoplasma
3) carrier animals source of infection
Mycoplasma spp. (2)
1) cause of conjunctivitis & keratoconjunctivitis
2) act alone or in coinfection
Species infected by Mycoplasma spp. that cause conjunctivitis & keratoconjunctivitis (5)
1) cats
2) sheep
3) goats
4) cattle
5) finches
Cause of keratitis (3)
1) Gram + cocci
2) S. pseudintermedius, B. hemolytic streptococci, S. canis, S. zooepidemicus
3) Pseudomonas aeruginosa
Pseudomonas aeruginosa (3)
1) poor pathogen
2) needs primary corneal damage to infect
3) may see melting ulcers
4) disease most associated is Equine keratitis
Pathogenesis of Pseudomonas aeruginosa (5)
1) pili mediate attachment & colonization of damaged stroma
2) multiplication & invasion into corneal stroma
3) production of exotoxins
4) kill corneal epithelial cells
5) keratitis will exudate
Clinical importance of melting ulcers
can cause rapid iris prolapse & globe collapse
What additional testing should be done if Pseudomonas aeruginosa is cultured and why?
Susceptibility testing because it is not predictably susceptible & lots of intrinsic antimicrobial resistance
Cause of keratoconjunctivitis (1)
Moraxella bovis
Diseased caused by Moraxella bovis (1)
Bovine keratoconjunctivitis aka PINK EYE
Moraxella bovis characteristics (3)
1) Gram - rods
2) coccobacilli
3) strict aerobes
Conditions that predispose to Moraxella bovis (6)
1) breeds that lack eye pigment
2) young
3) bull calf
4) UV exposure
5) dry/dusty conditions
6) crowded conditions