Actinomyces, Nocardia, Dermatophilus Flashcards
What species does Actinomyces bovis typically effect?
cattle and horses
What does Actinomyces bovis cause in cattle?
lumpy jaw (granulomatous osteomyelitis)
What does Actinomyces bovis cause in horses?
fistulous withers and poll evil infection
How does Actinomyces bovis show up on a gram stain?
gram positive filamentous or short rods that appear as cocci
What type of organism is Actinomyces bovis in relation to oxygen?
extreme microaerophile
What forms in tissues as a result of Actinomyces bovis and why?
‘sulfer granules’ because the organisms produce glycocalyx that cements them together
What is the natural habitat of Actinomyces bovis?
it is an obligate parasite of the oropharynx and digestive tract
What is the pathogenesis of granulomatous osteomyelitis in cattle?
the organism enters the dental alveoli or through trauma wounds in the gums or oral mucosa, then the lesions enlarge and produce a large necrotic are that eventually drains to the exterior, the draining pus contains the ‘sulfer granules’ that are assocciated with this lesion
What other organism is commonly associated with lumpy jaw infections in cattle?
Trueperella pyogenes
Fistulous withers is an infection of the _______ _______.
supra-atlantoid bursae
Poll evil is an infection of the ___________ ________.
supraspinous bursae
What type of horses usually get fistulous withers or poll evil?
horses that are used as work animals because their collars can cause irritation in these areas
What other organism is commonly associated with fistulous withers and poll evil?
Brucella abortus
What type of immunity is associated with Actinomyces bovis?
cell-mediated but once the lesions form it is difficult for the immune system
Is Actinomyces bovis treatable?
yes with extended antimicrobial treatment (antibiotics combined with IV sodium iodide) but lumpy jaw is hard to treat due to the osteomyelitis
What is the most common cause of actinomycosis in dogs?
Actinomyces viscosus
What is the natural habitat of Actinomyces viscosus?
it is an obligate parasite of the oropharynx and digestive tract
What type of organism is Actinomyces viscosus in regards to oxygen?
aerobic
What lesions are associated with Actinomyces viscosus?
pyothorax
What is the pathogenesis of Actinomyces viscosus?
it invades wounds in dogs frequently in the head or neck areas leading to pyothorax
What is found in the pus in lesions due to Actinomyces viscosus?
sulfur granules
What is Actinomyces viscosus associated with in hamsters and humans?
peridontal disease
What type of immunity is associated with Actinomyces viscosus?
cell-mediated immunity
Is Actinomyces viscosus treatable?
yes with antimicrobials
What does Actinomyces suis cause in sows?
granulomatous and supparative mammary gland lesions
What is the natural habitat of Actinomyces suis?
oropharynx in pigs
What is the pathogenesis of Actinomyces suis?
it is associated with superficial wounds of the mammary gland during suckling
What is the ‘typical lesion’ associated with Actinomyces suis?
actinomycotic granuloma which contains sulfer granules when it drains
What are the lesions associated with actinomycosis in humans?
first peridontal disease, then as it spreads thoracic and pulmonary infections, abdominal infections, and genital infecitons
What is used to treat actinomycosis in humans?
penicillin
How does the genus Nocardia show up on gram stain?
gram-positive rods that form branching filaments
What type of organism is the genus Nocardia in regards to oxygen?
aerobic
What lesions does Nocardia asteroides cause in dogs and cats?
suppurative thoracic and subcutaneous lesions
What disease in cattle is Nocardia asteroides associated with?
mastitis
Nocardia asteroides and Corynebacterium pseudotuberculosis create similar colonies, what key characteristic differentiates the two?
Nocardia asteroides takes longer to grow - typically 3-6 days
What do colonies of Nocardia asteroides look like?
they are yellow to orange and often appear dry and rough
How does Nocardia asteroides respond to a catalase test?
it is catalase positive
How does Nocardia asteroides respond to acid-fast staining?
it is partially acid-fast
What is the natural habitat of Nocardia asteroides?
soil
How is Nocardia asteroides transmitted?
via wounds, ingestion, and inhalation
What lesion is associated with infection of Nocardia asteroides in the respiratory system in dogs and cats?
pyothorax
What is observed with subcutaneous infections in Nocardia asteroides?
draining tracts
Are infections of Nocardia asteroides localized or do they metastasize?
they usually metastasize
How is Nocardia asteroides treated?
with surgical drainage or debridement, and aggressive antimicrobial therapy
How is Nocardia asteroides treated in cattle specifically?
it isn’t because it is not responsive to antimicrobial treatment so the animals are culled
What species is Nocaria braziliensis associated with?
dogs and humans
What humans typically get nocardiosis?
immunocompromised humans such as AIDS patients, cancer patients, chronic alcoholics, and transplant recipients
What species of Nocardia typically infects humans?
Nocardia asteroides
What clinical signs and lesions are associated with nocardiosis in humans?
supparative lesions and abscesses; headaches and convulsions
What is the cause of dermatophilosis?
Dermatophilus congolensis
What does Dermatophilus congolensis look like on gram stain?
gram positive rods
What is the life cycle of Dermatophilus congolensis?
it forms filamentous groups of organisms which release motile zoospores that grow and form a germ tube and eventually new filaments which then divide
What is the natural habitat of Dermatophilus congolensis?
soil
What species does Dermatophilus congolensis infect?
cattle, dogs, horses, sheep, deer, and captive wild animals
What season is associated with a heightened amount of Dermatophilus congolensis infections?
rainy season in tropical areas
What is the pathogenesis of Dermatophilus congolensis?
trauma such as tick bites are often associated with disease, serum and cell debris form into large, thick scabs
How is Dermatophilus congolensis diagnosed?
a smear of the exudate under the scabs can be air dried and stained with Giemsa stain
What is the treatment for Dermatophilus congolensis?
penicillin
