Erysipelothrix rhusiopathiae
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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
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
- Clinical sighns:
- Cutaneous erysipelas
- Polyarthritis in lambs
- Rarely fatal septicaemia
- Enters via:
- Cuts, abrasions
- Castration or docking wounds
- Haematogenous spread -> subacute or chronic fibrinopurulent polyarthritis
- Morbidity up tp 50%
- Affects mostly unthrifty lmbs
- Fibrosis and osteophyte formation in later stages -> persistent lameness
- Clinical sighns:
- Corynebacterium pyogenes
- May cause post-dipping joint infections
- Streptococcus spp.
- Commonly cause suppurative polyarthritis in lambs
- Naval infection -> bacteriamia -> polyarthritis
- May also cause blindness and nervous signs if uvea or meninges are affected
- Larger joints are more afected
- May spread to other organs
- Staphylococci
- Sporadically infect joints
- May complicate 'tick-borne fever'
- Chlamydia sp.
- Sporadic or outbreaks of lamb polyarthritis
- High morbidity, low mortality
- Commonly together with conjunctivitis
- Most recover but may remain lame
Human erysipeloid
- Infection through skin wounds from fish and poultry
- Localised cellulitis
- Occasional joint and heart disease after haematogenous spread if untreated