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
Transmission of Moraxella bovis (2)
1) infected carrier animals
2) mechanical transmission; flying insects
Pathogenesis Moraxella bovis (3)
1) damage to the eye
2) fimbrie (pili) allow for attachment
3) Hemolysin
What is the basis for the Moraxella bovis vaccine?
Fimbrie (pili)
Potential sequelae to Bovine keratoconjunctivitis (2)
1) globe rupture
2) secondary infection: hypopyon
Prevention/control for Bovine keratoconjunctivitis (5)
1) avoid predisposing factors
2) isolate affected animals
3) decrease stocking rates
4) add shade/fly control
5) VACCINATION**
Cause for periocular infections
Dermatophytes (ringworm)
Cause for surface ocular infections: Fungal keratitis (3)
1) fusarium
2) penicillum
3) aspergillus
What species is fungal keratitis most common
Horses
Transmission of fungal keratitis (1)
1) innoculation of organisms into traumatized corneal epithelium
Virulence factors for fungal keratitis (2)
1) may inhibit corneal neovascularization
2) reduced neutrophil infiltration & cell-mediated phagocytosis & result in impeded healing
Causes of Viral keratitis/conjunctivitis (2)
1) feline herpes
2) Distemper
Feline herpes virus-1
1) contact with nasal, oral & conjunctival secretions of infected animals
2) short replication cycle
3) rapid cell to cell spread
4) tendency to induce cell lysis
5) persistence in sensory ganglia
Sequele of feline herpes virus-1
symbepharon= adhesion of the conjunctiva to itself or to the cornea
Canine distemper (3)
1) acute blephritis & conjunctivitis (1st clinical sign)
2) acute keratoconjunctivitis
3) intraocular & extraocular disease
Causes of viral corneal edema
Canine adenovirus-1
canine adenovirus-1 (5)
1) cause of infectious canine hepatitis
2) diffuse corneal edema “Blue eye”
3) deposit of immune complexes on endothelial cell of the eye
4) anterior uveitis
5) intraocular and extraocular disease
Diseases that cause intraocular infections (5)
1) Leptospirra spp.
2) Gram - bacteria
3) Rickettsial infection
4) Viral infections
5) Fungal infections
Leptospirra spp. (2)
1) anterior uveitis (ERU)
2) important in horses
Gram - bacteria that can cause intraocular infections (4)
1) enterobacterales
2) histophilus somni
3) Borrelia burgdorferi
4) Brucella canis
Causes of rickettsial eye infections (2)
1) Ehrlichia canis
2) Rickettsia rickettsii
Causes of viral intraocular infections (3)
1) Feline coronavirus
2) Feline leukemia virus
3) Malignant catarrhal fever
Feline coronavirus (3)
1) ocular manifestation predominantly in the “dry” form
2) bilateral granulomatous anterior uveitis & chorioretinitis
3) frequently see large keratic percipitates in anterior chamber
Feline leukemia virus (3)
1) ocular manifestation is ocular lymphosarcoma
2) uveal tract common for metastasis
Signs of feline leukemia virus (5)
1) mild uveitis
2) aqueous flare
3) keratitic precipitates
4) iris thickened- progression
5) glaucoma- progression
Causes of fungal eye infections (3)
1) Histoplasmosis
2) Blastomycosis
3) Cryptococcosis
Fungal eye infection characteristics (3)
1) severe systemic fungal infections have ocular signs
2) associated w/ posterior uveitis & anterior uveitis & chorioretinitis
3) ocular signs are the primary clinical manifestation of systemic mycosis
Histoplasmosis (2)
1) Ohio, Missouri, Mississippi
2) can occur in cats; uncommon in dogs
Blastomycosis (2)
1) mississippi/ohio & central atlantic states
2) ocular lesion in ~50% of dogs
Ocular lesions of Blastomycosis (3)
1) chorioretinitis
2) anterior uveitis
3) endophthalmitis
Cryptococcosis (2)
1) most common feline mycotic
2) chorioretinitis w/ granulomatous inflammation & retinal detachment; optic neuritis
Parasitic intraocular infectious causes
Toxoplasma gondii
Toxoplasma gondii (4)
1) most common lesion is chorioretinitis
2) multifocal dark gray infiltrates in the tepetal fundus
3) fluffy white infiltrates in the nontepetal fundus
5) +/- anterior uveitis
