Lecture 8 9/26/23 Flashcards by Danika Boltz

What are the general characteristics of Corynebacterium spp.?

-gram-pos., pleomorphic, aerobic rods
-lipid-rich cell wall
-survive in macrophages
-cause pyogenic/pyogranulomatous infections
-commensals of mucus membranes and skin

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What disease is caused by Corynebacterium diphtheriae?

diphtheria

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What disease is caused by Corynebacterium pseudotuberculosis?

caseous lymphadenitis in sheep and goats

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What is the virulence factor of C. pseudotuberculosis?

-exotoxin, phospholipase D

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What is the pathogenesis of C. pseudotuberculosis?

-bact. replication in phagocytic cells
-inflammation and abscesses
-worsening disease with increasing age

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How does caseous lymphadenitis more commonly present in goats?

external form

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How does caseous lymphadenitis more commonly present in sheep?

internal form

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How do caseous lymphadenitis lesions appear in sheep?

distinctive, lamellated “onion skin”

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How do caseous lymphadenitis lesions appear in goats?

soft, pasty, “cheesy,” less organized abscess

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How is C. pseudotuberculosis diagnosed in an external presentation?

aerobic culture of pus from abscess

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How is C. pseudotuberculosis diagnosed in an internal presentation?

-radiography/ultrasound
-serology using SHI test with paired titers to detect phospholipase D exotoxin

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Why is a false negative possible when testing for internal C. pseudotuberculosis?

abscesses may wall off and not be accessible

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What are the treatment options for C. pseudotuberculosis?

-not curable
-lance and drain abscesses
-surgical excision
-intralesional antibiotics

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How is C. pseudotuberculosis controlled?

-biosecurity practices
-culling
-hygiene and management
-vaccination

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How does C. pseudotuberculosis present in horses?

-pigeon fever with development of chest lump
-causes ulcerative lymphangitis after entering through skin abrasions

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What bacteria fall into the Corynebacterium renale group?

-C. renale
-C. cystiditis
-C. pilosum

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What are the characteristics of the C. renale group?

-commensals of the urogenital tract
-cause bovine pyelonephritis and other urogenital/kidney infections

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Which Corynebacterium species can infect lab animals?

-C. kutscheri
-C. bovis

What are the characteristics of Rhodococcus equi?

-gram-pos., aerobic, rods or coccobacilli
-facultative intracellular
-intra-macrophage survival
-causes pyogranulomatous inflammation
-opportunistic

What are the characteristics of R. equi disease?

-serious cause of pneumonia in foals
-slow and progressive
-affects multiple body systems
-can be zoonotic for immunocompromised individuals

How can R. equi be diagnosed?

-cytology
-CBC/serum chem.
-thoracic rads
-culture
-PCR

How is R. equi treated?

combo of macrolide antibiotic and rifampin

What is important about R. equi prevention?

there is no available vaccine

What are the general characteristics of Nocardia spp.?

-pleomorphic and gram-pos.
-facultative intracellular
-pathogenic in immunocompromised individuals

What is important about Nocardia mastitis?

-antibiotic treatment is not successful -infected cows must be removed from herd or culled

What is unique about the exudate in wound infections caused by Nocardia spp.?

sulphur granules can be found within the exudate

How can Norcardia spp. be diagnosed?

-acid-fast stain -gram stain -aerobic culture -histopath.

How are Norcardia spp. treated?

-trimethoprim/sulfa -aminoglycoside/carbapenem combo

What are the general characteristics of Actinomyces spp.?

-normal flora of oral cav. -aerobic, anaerobic, or capnophilic depending on species -source of many antibiotics

What are the characteristics of Actinomyces disease?

-chronic infections associated with mouth and bite injuries -lesions contain sulfur granules -pyogenic response

What disease is caused by Actinomyces bovis?

pyogranulomatous osteomyelitis/lumpy jaw

How does Actinomyces hordeovulneris infect hunting dogs?

when fox tail grasses penetrate the animal and introduce the bacterium

How are Actinomyces spp. diagnosed?

-micro. examination -gram-stain -aerobic and anaerobic culture

How are actinomyces spp. treated?

-penicillin -surgical excision of foreign bodies

What are the characteristics of Dermatophilus congolensis?

-aerobic, gram-pos -filamentous/branching -infectious motile spores -tram track appearance -spores attracted to moist, damaged skin

What diseases are caused by Dermatophilus congolensis?

-rain scald in horses -strawberry foot rot in cattle -epidermal abscess diseases

How is D. congolensis diagnosed?

-micro. demonstration of tram track appearance -culture -PCR

How is D. congolensis treated and controlled?

-proper treatment with penicillin or tetracycline -isolation of infected animals

What are the characteristics of Trueperella pyogenes?

-pleomorphic and aerobic -important opportunistic pathogen in ruminants and swine -caused chronic purulent infections

How is T. pyogenes diagnosed?

aerobic culture

How is T. pyogenes treated?

penicillin

What is important about T. pyogenes control?

no vaccine available

What are the characteristics of Actinobaculum suis?

-anaerobic -commensal in prepucial mucosa -sexually transmitted -causes porcine cystitis and pyelonephritis