Lecture 8 9/26/23 Flashcards
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
What disease is caused by Corynebacterium diphtheriae?
diphtheria
What disease is caused by Corynebacterium pseudotuberculosis?
caseous lymphadenitis in sheep and goats
What is the virulence factor of C. pseudotuberculosis?
-exotoxin, phospholipase D
What is the pathogenesis of C. pseudotuberculosis?
-bact. replication in phagocytic cells
-inflammation and abscesses
-worsening disease with increasing age
How does caseous lymphadenitis more commonly present in goats?
external form
How does caseous lymphadenitis more commonly present in sheep?
internal form
How do caseous lymphadenitis lesions appear in sheep?
distinctive, lamellated “onion skin”
How do caseous lymphadenitis lesions appear in goats?
soft, pasty, “cheesy,” less organized abscess
How is C. pseudotuberculosis diagnosed in an external presentation?
aerobic culture of pus from abscess
How is C. pseudotuberculosis diagnosed in an internal presentation?
-radiography/ultrasound
-serology using SHI test with paired titers to detect phospholipase D exotoxin
Why is a false negative possible when testing for internal C. pseudotuberculosis?
abscesses may wall off and not be accessible
What are the treatment options for C. pseudotuberculosis?
-not curable
-lance and drain abscesses
-surgical excision
-intralesional antibiotics
How is C. pseudotuberculosis controlled?
-biosecurity practices
-culling
-hygiene and management
-vaccination
How does C. pseudotuberculosis present in horses?
-pigeon fever with development of chest lump
-causes ulcerative lymphangitis after entering through skin abrasions
What bacteria fall into the Corynebacterium renale group?
-C. renale
-C. cystiditis
-C. pilosum
What are the characteristics of the C. renale group?
-commensals of the urogenital tract
-cause bovine pyelonephritis and other urogenital/kidney infections
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
