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28 Cards in this Set
- Front
- Back
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Whats the morphology and characteristics of Actinomyces?
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a. non-spore-forming, branching G+ rods, may have coccobacillary forms.
b. may look identical to Nocardia c. not acid-fast d. facultative anaerobe e. slow-growing (48-72hrs) f. requires serum or blood in culture media (rich medium) |
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Where will you normally find Actinomyces?
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a. commensals on mucous membranes of oral cavity, pharynx, other GI tract sites; dental plaque.
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Whats the mode of transmission for Actinomyces?
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a. commonly endogenous
b. possibly transmitted by bite wounds c. readily inactivated with heat and most disinfectants |
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What is the pathogenesis for Actinomyces?
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a. details of pathogenesis unkown
b. usually polymicrobial infection; more pathogenic in pressence of other bacteria c. may co-aggregate with other bacteria and avoid phagocytosis d. multiplication in tissue --> suppurative (neut) to pyogranulomatous (mono + neut) inflammation e. fistulous (deeply seeded infection) tracts carry exudate to surface |
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What are some of the clinical conditions associated with Actinomyces?
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A. rumminants (Actinomyces bovis):
a. normal inhabitant of oropharynx, GI tract b. usually result of introduction via oral trauma c. "lumpy jaw" d. osteomyelitis, irregular bony replacement; honeycombed with abscesses and fistulous tracts e. hallmark is pyogranulomatous inflammation f. most commonly affects mandible g. lesions also occur in esophagus, reticulum B. Swine (Actinomyces bovis/suis) a. occasionally pyogranulomatous mastitis, or pneumonia (with other pathogens) C. Horses (A. bovis) a. may be associated with supra-atlantal ("poll evil") or supraspinous ("Fistulous withers") bursitis b. poll evil for fistulous withers usually also associated with other bacT. D. dogs and cats (A. viscosus, A. hordeovulnaris) a. carried into tissues via plant awns b. abscesses, draining tracts. c. pyogranulomatous inflammation with fistulous tracts d. Thoracic: chronic condition with pneumonia, pyothorax, granulomatous lesions. e. abdominal: chronic with abscesses, peritoneal effusions f. retroperitoneal: bertebral bodies, adjacent tissue affected; ofthen with draining tract. g. localized granulomatous abscess of skin and subcutis occur |
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How would you diagnose Actinomyces?
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a. collect aspirates from unopened lesions or tissues
b. "sulfur granules' in exudate - small (1-3mm) yellow particles - crushand stain granules to identify branching, G+, beaded filaments. c. submit granules for culture if possible d. growth may take 2-7 days on blood agar, brain-heart infusion agar. e. growth enhanced in presence of CO2 |
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What are the treatment and control for Actinomyces?
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a. debride, drain abscesses, effusions
b. often responds to penicillin: difficult to get antibiotic to site of infection; treat for weeks to months; relapse common c. no vaccine d. avoid tissue exposure (management) feed quality; removal of plant awns |
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Lumpy jaws
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bacteria stained from crushed sulfur granules.
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L: growth enhanced in presence of CO2 (molar tooth appearance)
R: w/o CO2 |
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What are the morphology and characteristics of Nocardia?
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a. nonmotile
b. non-spore-forming c. G+ d. coccobacillary forms rods with branching filaments e. partially acid-fast strict aerobes, slow growth in culture |
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Where will you normally find Nocardia?
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a. saprophytes found in soil, water
b. ubiguitous c. thrive in environment; inactivated by bleach, benzalkonium chloride. d. decaying vegetation, animal feces |
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What is the mode of transmission for Nocardia?
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a. trauma
b. inhalation c. ingestion d. equipment/personnel induced mastitis |
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What is the pathogenesis for Nocardia?
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a. survives in phagocytic vacuoles: cell wall lipids, mycolic acid may prevent phagolysosome fusion
b. superoxide dismutase and catalase believed to protect from oxidative destruction in phagocytes c. local/regional infection, inflammation --> lymphatic or hematogenous spread may occur d. suppurative to pyogranulomatous inflammation. |
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What are some common clinical conditions associated with Nocardia?
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A. Ruminants:
a. Mastitis: acute (fever, abnormal milk, swelling); chronic (fistulous tracts, granulomatous inflammation) B. Horses a. localized skin or L.N. abscesses b. local or generalized infections occur in immunosuppressed horses c. abortion (rare) C. Fish a. granulomas in muscles, internal organs D. Guinea pigs a. ear infections, mastitis, fistula granuloma in muscles. E. dogs and cats a. localized - often penetrating wound : may be most common manifestation in cats; subcutaneous, fistulous tracts with or w/o L.N. invovement b. Pulmonary form: more common in dogs; pulmonary masses, hilar lymphadenomegaly, extrapulmonary masses, bronchointerstitial to alveolar infiltrates, pleural effusion c. Dissemination possible |
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How would you diagnose Nocardia?
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a. cytology
b. Exudates may contain particles of bacteria + inflammatory cells c. identification by biochemical tests, molecular methods. |
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How would you treat and control Nocardia?
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a. Difficult due to type of lesion; often requires debridement
b. trimethoprim-sulfa drugs often effective: long term treatment required; susceptibility testing c. no vaccine; avoid exposure d. rarely, human infections associated with bite or scratch wounds from healthy dogs, cats. |
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How would you differentiate Actinomyces from Nocardia?
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Whats the morphology and characteristics for Dermatophilus congolensis?
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a. G+ branching, segmented, filamentous rods --> fragment to coccoid cells --> mature to motile coccoid zoospores
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Where will you normally find Dermatophilus congolensis?
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a. obligate parasite --> lives on skin of animals cattle, horses, sheep, goats, and others
b. survival rate is poor in environment c. worldwide distribution: most economic significance in tropical, subtropical climates |
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What is the mode of transmission for Dermatophilus congolensis?
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a. direct contact
b. fomites c. insects (biting flies, ticks) |
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What is the pathogenesis for Dermatophilus congolensis?
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zoospores "germinate" and proliferate in epidermis, somtimes hair follicles --> neutrophilic inflammation under infected epidermis --> new epidermis also infected --> layers of crusted neutrophilic exudate and infected keratinizing epidermis.
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Dermatophilosis (streptothricosis)
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a. lesions occur in multiple species: a few scabbed areas; large areas of loss of epidermis with secondary infection, parasitism; possible loss of animals
b. predisposing conditions: rainy/humid weather; mechanical trauma (injuries, fly or tick bites) |
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What are some clinical conditions associated with Dermatophilus congolensis?
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A. Ruminant
a. discrete scabs and crusts; progressive form may occur with ulcerative lymphangitis B. Horses a. scabs and crusts to "rain scald" lesions on the back and "grease heel" or "rain rot" of the leg C. Sheep and goats a. strawberry foot rot: ulcerative dermatitis of lower leg, foot.; lumpy wool: dermatitis of wool-covered areas; facial, scrotal dermatitis D. dogs and cats skin crusts on dogs; cats may get deeper abscesses in muscle, L.N., SQ tissue (introduced by puncture wound) |
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How would you diagnose Dermatophilus congolensis?
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a. smears of macerated scabs and crusts: segmented filaments "rail road ties" "stacked coins", coccoid spores
b. growth on blood agar in 5-10% CO2 may take 2 days |
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How would you treat and control Dermatophilus congolensis?
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a. remove crusts and scabs, clean well with soap
b. some recommend topical disinfectants such as povidone iodine c. treat with antibiotics if severely affected (high dose penicillin, +/- aminoglycoside) d. keep clean and dry e. no vaccine f. possible zoonotic transmission. |
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Dermatophilus congolensis
note scabs and crusts on the back and at the flank area. |
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Dermatophilus congolensis
note the stacked coin appearance |
