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26 Cards in this Set
- Front
- Back
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Gram-positive, non-spore forming, non-motile organisms - Ubiquitous in environment (commensals of some plants and animals) - Some pathogenic genera (mycobacterium spp, corynebacterium spp, nocardia spp, rodococcus spp) |
ACTINOBACTERIA |
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Actinobacterial diseases are opportunistic.
True or False? |
TRUE |
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Nocardia spp general characteristics? |
ACTINOBACTERIA (non-motile/non-spore forming) - Strict aerobe - Aerial hyphae - Wide distribution = soil, water, air, sewage - Acid fast - Causes: brain abscesses! |
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Describe the three species of Nocardia that affect dogs, horses and cows. |
1. N. asteroides = most frequent nocardial pathogen - causes subcut infections in dogs! 2. N. brasiliensis - causes pneumonia in horses 3. N. otitidis caviarum - bovine mastitis |
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Describe the pathogenesis of Nocardia spp. |
Organism inhaled, ingested or picked up by wound (Direct or hematogenous spread) - Resists phagocytosis - walls off abscesses preventing penetration of WBCs - Chronic invasive pyogenic infections (no sulfur granules) - Treatment is difficult and prolonged! |
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Three clinical forms of Nocardia spp? |
- Three clinical forms: 1. Cutaneous 2. Respiratory (pyothorax) = common in cats 3. Systemic = pyrexia, cough, neurological signs |
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Disease/symptoms of Trueperella pyogenes (= arcanobacterium pyogenes)? |
1. Abscesses = focal & disseminated (to organs) 2. Wound infections 3. Septic arthritis 4. Secondary respiratory infections 5. Reproductive impairment 6. Secondary/mixed infections (Mastitis & foot abscesses) * Can infect many species (all livestock) in many different ways! |
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Virulence factors of Trueperella pyogenes? |
1. Protease = necrosis/suppuration 2. Hemolytic exotoxin = dermonecrotic 3. Neuraminidase = NanH/NanP adhesion 4. Pyolysin (PLO) = essentially hemolytic but effects both RBCs and WBCs |
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Pathology of actinobacteria?
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1. Chronic inflammation 2. Focal or disseminated lesions 3. Granulomatous lesions - e.g. abscesses, plelonephritis, lymphadenitis, osteomyelitis |
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What are the four main genera of Actinobacteria of concern in vet med? |
1. Nocardia spp 2. Trueperella 3. Actinomyces spp 4. Corynebacterium spp |
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General characteristics of actinomyces species? |
ACTINOBACTERIUM: (non-motile/non-spore forming) - Non-acid fast with branching - Microaerophilic or anaerobic - Produce pyogenic, granulomatous reactions (sulphur granules) |
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Actinomyces species of concern in vet med? |
1. Actinomyces bovis - Causes lumpy jaw (osteomyelitis) in cattle - Thick yellow pus with sulphur granules 2. A. viscosus = dogs mainly (but most other spp) - Thoracic lesions & osteomyelitis 3. A. suis - Mastitis in pigs; initiated by trauma |
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General characteristics of Corynebacterium spp? |
ACTINOBACTERIUM - Small, pleomorphic gram+ rods = chinese letters - Pyogenic, common commensals |
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What are the corynebacterial species of veterinary interest? |
1. Corynebacterium renale = cattle - Causes cystitis, pyelonephritis, & balanoposthitis (inflamed urethra in males post-mating) 2. Corynebacterium ulcerans = cats = zoonotic 3. C. psuedotuberculosis = ruminants & horses; Caseous lymphadentis (CLA) |
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Virulence factors for Corynebacterium Renale? |
1. Pili = adherence 2. Renalin = cell lysis 3. Urease = lowers pH in UT accommodating infection 4. Caseinase |
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Pathogenesis of C. renale? |
Adhere to urogenital mucosa - "Stress" = proliferation - Ascending infection - Inflammation - Cystitis/pyelonephritis |
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Pathogenesis of Corynebacterium pseudotuberculosis resulting in Caseous Lymphadenitis (CLA)? |
Corynebacterium pseudotuberculosis gains entry to host through wounds or flies (transfer of pus) - Drains to local drainage lymph node & spreads within animal from their resulting in onion-like, layers of pus forming within lymph nodes = CLA |
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Virulence factors of C. Pseudotuberculosis? |
1. Phospholipase D (PLD) = prevents inflammatory cell chemotaxi 2. Mycolic acid = allows survival in macrophages 3. Serine protease (Cp40) 4. Siderophore = acquisition of iron from the host |
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Prevention strategies against Caseous Lymphadenitis, caused by Corynebacterium pseudotuberculosis? |
1. VACCINES - targets PLD 2. Diagnosis - ELISA Test; detection of anti-PLD antibodies as a marker |
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Most important Listeria spp in vet med? |
1. L. monocytogenes - Meningoencephalitis, septicemia, abortion, pyogenic infection 2. L. ivanovii - Abortion & systemic infections |
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General characteristics of listeria spp? |
- Commensal (tonsils, intestines) & environmental organism - Grows at low & high temps (4-45C) |
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Clinical signs of listeriosis? |
1. Meningoencephalitis (inflammation of brain) - Circling disease, fever, blindness, headpressing, paralysis & death in 2-3 days 2. Abortion due to crossover into amniotic fluid3 3. Subclinical mastitis & milk contamination |
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Pathogenesis of Listeriosis? |
Various routes of entry with varying pathogenesis: 1. CNS infection = bacteria enters mucosa via oral inoculation of some kind, bacteria travels up trigeminal nerve into brainstem & causes inflammation 2. Transmammary = epithelial invasion causing bactermia and either neonatal septicemia or placentitis leading to abortion. 3. Nasal mucosa & conjunctiva |
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Pathogenic mechanisms/virulence factors of listeria? |
1. Bacerial protein internalin (inIA) results in cell uptake (by macrophages or epithelial cells) 2. Once inside cell, bacteria escape the hijacked cell via Listeriolysin (LLO) 3. Multiply in cytoplasm and via actin based motility (ActA) spread laterally to adjacent cells |
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Pathogenesis & Infections caused by ERYSOPELOTHRIX RHUSIOPATHIAE? |
PATHOGENESIS: E. Rhusiopathiae is a commensal in pigs & when there's a depression of host defenses this allows multiplication of virulent strains - Entry via tonsils or cuts/abrasion - Invade neutrophils INFECTIONS: 1. Acute = Septicemia (smooth) 2. Subacute urticarial form = "Diamond" Skin Disease in pigs 3. Chronic = arthritis/endocarditis, chronic inflammation (rough) |
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General characteristics of Erysipelothrix Rhusiopathiae? |
- Commensal, widespread in animals - ZOONOTIC - Infections mainly in pigs, but also in sheep, turkeys and others - Smooth & rough forms associated with diff diseases: Smooth = acute septicemia in pigs, turkeys and sub-acute skin lesions in pigs Rough = chronic arthritis in sheep & endocarditis in pigs |
