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Actinomycetales |
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Some similarities to fungi
- Growth as filaments
- Wrinkled or fuzzy colonies
True bacteria
- Peptidoglycan
- Prokaryotic
Three genera
- Nocardia
- Actinomyces
- Dermatophilus
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Actinomycotic infections |
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Lesions - chronic
May cause mycetoma
- Swelling
- Draining sinuses
- Granules
Treatment
- Need prolonged therapy
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Nocardiosis |
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Cattle
- Mastitis -- chronic, difficult to treat
- Farcy
Dogs
- soft tissue abscesses
- Bite wounds or traumatic injury
- Purulent, bloody -- “tomato soup”
Other species
Humans
- can mimic tuberculosis
Pathogenesis
- not an anaerobe
- Reservoir -- soil
- Facultative intracellular pathogen
- Requires CMI
Diagnosis
- culture, can be acid-fast
Treatment
- Sulfa-trimethoprim
- Penicillin
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Clinical Case |
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History
- 18 mo. old Male Pointer
- Lost weight for several months
- First vet - diagnosed “prostate problem,” temporary relief from short course of antibiotics
- 2nd Vet - “kidney problem”, outcome same as above
- 3rd Vet - suspected abdominal abscess, did exploratory, found nothing,, referred dog to VMTH
Exam
- Emaciated, pale mucous membranes, dyspnea.
- Difficult to hear heart sounds
- What does this suggest?
- Did aspirate of thoracic cavity
- Removed 300 cc of bloody purulent exudate
- What would you do next to diagnose the cause of the exudate?
- Based on your answer above, what course of therapy do you think was recommended?
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Actinomycosis |
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- Actinomyces bovis -- cattle
- Actinomyces viscosus -- dogs
- Actinomyces israelii -- humans
- Tend to be chronic infections
- Reservoir is usually normal flora, endogenous flora or through bite wound
- Most species are anaerobes
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"Lumpy Jaw" |
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Principally in cattle
Traumatic injury to oral cavity
- Normal flora
- Inoculate into soft tissue
- Somewhat anaerobic
Chronic lesions -- mycetoma
- Tend to invade bone
- Contrast with "wooden tongue" -- soft tissue
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Actinomycosis |
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Swine
- soft tissue, bit e wounds
Dogs and cats
- thoracic abscesses
- Purulent, bloody -- "tomato soup"
Human periodontal disease
- A. viscosus -- chronic inflammation, bone loss
Diagnosis
- culture, anaerobe
Treatment
- penicillin
Host response
- inflammation, CMI, Ab not protective
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Actinomyces pyogenes |
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- Formerly Corynebacterium pyogenes
- Soft tissue abscesses
- Pneumonia
- Particularly a problem in young animals, or in combination with other pathogens
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Dermatophilosis |
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Dermatophilus congolensis
- "Lumpy wool disease", "strawberry footrot"
Pathogenesis
- Motile zoospores -- swim on wet skin
- Invade epidermis -- attracted to CO2
Host response
- lots of PMNs
Diagnosis
- lesions, visualize organisms
Treatment
- Penicillin, other antibiotics
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