Difference between revisions of "Erysipelothrix rhusiopathiae"

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===Swine erysipelas===
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===[[Swine Erysipelas]]===
  
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*Carrier pigs act as reservoir of infection
 
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*Organisms excreted in faeces of acutely-affected pigs
 
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*Ingestion of contaminated food and water, or via skin abrasions
 
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*Clinical outcome depends on susceptibility of pigs and virulence of strain
 
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*Pigs susceptible after maternal antibody waned (after 3 months) and before protective immunity acquired (3 years)
 
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*Change in diet, extremes of temperature and fatigue thought to predispose to infection
 
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*Septicaemic form:
 
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**Acute; incubation period 2-3 days
 
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**Pigs found dead, febrile, depressed, recumbent or with stilted gait
 
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**Mortality high
 
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**Pregant sows abort
 
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*Cutaneous form:
 
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**Diamond skin lesions
 
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**Fewer systemic signs, mortality rates lower
 
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**Pigs febrile with small, pink/purple raised areas or extensive diamond-shaped plaques over skin
 
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**Lesions may resolve within a week, or become necrotic and slough
 
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*Arthritis:
 
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**Older pigs, chronic
 
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**Stiffness, lameness, non-weight bearing on affected limbs
 
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**Joint lesions with erosion of articular cartilage, fibrosis and ankylosis
 
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**Strong impact on productivity
 
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*Chronic valvular endocarditis:
 
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**Vegetatic thrombosis of mitral valves
 
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**Asymptomatic or congestive heart failure and sudden death with stress
 
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*Diagnosis:
 
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**Diamond-shaped skin lesions
 
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**Haematology and post mortem, especially liver, [[Spleen - Anatomy & Physiology|spleen]], heart valves, synovial tissues
 
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**Slender Gram-positive rods on microscopy of acute lesions; filamentous forms in chronic lesions and smears
 
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**No growth on MacConkey agar
 
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**Colonial characteristics and biochemical tests
 
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*Treatment:
 
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**Penicillin and tetracyclines for acute infections
 
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**Hyperimmune serum
 
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*Control:
 
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**Hygience
 
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**Cull chronic cases
 
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**Isolate affected pigs
 
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**Live attenuated or inactivated vaccines
 
  
 
===Turkey erysipelas===
 
===Turkey erysipelas===
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*Occasional joint and heart disease after haematogenous spread if untreated
 
*Occasional joint and heart disease after haematogenous spread if untreated
 
[[Category:Bacteria miscellaneous]][[Category:Gram_positive_bacteria]][[Category:Rods]][[Category:Pig]][[Category:Sheep]][[Category:Poultry]]
 
[[Category:Bacteria miscellaneous]][[Category:Gram_positive_bacteria]][[Category:Rods]][[Category:Pig]][[Category:Sheep]][[Category:Poultry]]
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[[Category:To_Do_-_Bacteria]]

Revision as of 10:18, 25 June 2010

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Overview

  • Causes erysipelas in pigs and turkeys worldwide
  • Arthritis and discospondylitis in pigs as well as cutaneous lesions
  • Occasionally causes arthritis in sheep and disease in other animals
  • Causes erysipeloid, a localised cellulitis in humans
  • Found in porcine tonsils - 50% of pigs are thought to be carriers
  • Bacteria excreted in faeces and oronasal secretions
  • Survive in soil for less than 35 days
  • Present on fish


Characteristics

  • Gram-positive, small rod (smooth form) or filamentous (rough form)
  • Facultative anaerobe
  • Non-motile
  • Catalase negative, oxidase negative, coagulase positive
  • Grow on nutrient agar; growth enhanced by addition of blood or serum
  • Small colonies with incomplete haemolysis in 48 hours
  • Hydrogen sulphide formed as black central line in TSI agar
  • Growth over wide rangs of temperatures and pH


Identification and diagnosis

  • Isolates from acute infections produce smooth colonies; 1.5mm diamteter, convex and circular with even edges
  • Isolates from chronic infections produce rough colonies; larger, flat and opaque colonieswith irregular edges
  • Biochemical tests
  • Serotypying according to a heat-stable peptidoglycan extracted from the cell wall
  • Virulence testing in lab animals
  • PCR for detection of virulent isolates


Pathogenesis and pathogenicity

  • Route of infection: ingestion from pig faeces
  • Entry via tonsils, skin or mucous membranes
  • Capsule prevents phagocytosis
  • Adhere to endothelial cells
  • Produce neurominidase which enhances cell penetration
  • Septicaemia with vascular damage
  • Swelling of endothelial cells, monocyte adherence to vascular walls and hyaline microthrombus formation
  • Bacteria localise in synovia of joints and on heart valves during bacteraemia and cause chronic lesions
  • Host immune response to persistent bacterial antigens causes long-term damage to the joints


Swine Erysipelas

Turkey erysipelas

  • Affects birds of all ages
  • Excreted in semen, causing death of turkey hens 4-5 days after AI
  • Septicaemia
  • High mortality
  • Dark, swollen snoods
  • Enlarged friable liver and spleen on post mortem
  • Arthritis and vegetative endocarditis and emaciation with chronic infections
  • Inactivated vaccine

Sheep infections

  • Non-suppurative polyarthritis of lambs from contamination of navel or tail-docking/castration wounds
  • Cellulitis and laminitis in older lambs and ewes causing post-dipping lameness - entry through skin abrasions in hoof from contaminated dip
  • Valvular endocarditis and pneumonia in ewes reported


Human erysipeloid

  • Infection through skin wounds from fish and poultry
  • Localised cellulitis
  • Occasional joint and heart disease after haematogenous spread if untreated
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