Difference between revisions of "Bacterial skin infections - Pathology"

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===[[Deep pyoderma]]===
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===[[Deep Pyoderma]]===
  
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*Less common than superficial pyoderma
 
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*Occurs mainly in dogs
 
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*Affects infundibulum, isthmic portion of hair follicles and surrounding dermis and subcutis
 
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*Heals with scarring
 
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*Local lymph nodes are often affected
 
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*Often secondary to immunosuppression, follicular hyperkeratosis or [[Parasitic skin infections - Pathology#Demodicosis|demodicosis]]
 
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*May also be a sequele to [[Bacterial skin infections - Pathology#Superficial pyoderma|superficial pyoderma]]
 
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*Grossly:
 
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**[[Skin Glossary - Pathology|Crusted papules, pustules, alopecia, abscesses, nodules, fistulas, ulcers, haemorrhagic bullae]]
 
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**In dogs may look similar to [[Pyotraumatic Dermatitis|pyotraumatic dermatitis]]
 
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*Microscopically:
 
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**Pyogranulomatous folliculitis and furunculosis
 
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**Nodular or diffuse dermatitis
 
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**Panniculitis
 
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*May involve a foreign bodey reaction to follicular contents and draining sinuses develop
 
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*If chronic, scarring and loss of adnexa
 
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*Bacteria often isolated include [[:Category:Staphylococcus species|''Staphylococcus'' spp.]], especially ''S. intermedius'' in dogs, [[:Category:Streptococcus species|''Streptococcus'' spp.]], ''[[Corynebacterium pseudotuberculosis]]'', [[:Category:Pseudomonas and Burkholderia species|''Pseudomonas'']], [[:Category:Pasteurella and Mannheimia species|''Pasteurella'']], [[Proteus|''Proteus'']], [[Escherichia coli|''E.coli'']]
 
  
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====[[Staphylococcal Folliculitis and Furunculosis]]====
 
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====[[Subcutaneous Abscesses]]====
 
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*Purulent exudate within dermis and subcutis
 
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*Commonly occurs in cats due to contamination of penetrating wounds
 
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*Surrounding wall of collagen and fibroblasts may develop
 
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*Common bacteria (often normal mouth flora)
 
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**[[Pasteurella multocida|''Pasteurella multocida'']], [[Fusobacterium necrophorum|''Fusobacterium'' spp.]], [[:Category:Streptococcus species|beta - haemolytic streptococci]], [[Bacteroides|''Bacteroides'']]
 
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[[Category:Integumentary System - Bacterial Infections]]
 
  
  

Revision as of 19:10, 21 February 2011


Cutaneous bacterial infections tend to be called pyodermas. They are superficial, deep and are common in dogs, but less common in other species.




Deep Pyoderma

Bacterial Granulomatous Dermatitis

  • Usually due to saprophytes
  • Grossly:
    • Diffuse or nodular lesions
    • May ulcerate and form drainage fistulas
  • Microscopically:
  • Mycobacterial granulomatous or pyogranulomatous lesions
    • Usually caused by Mycobacterium lepraemurium (feline leprosy) or other Mycobacteria
    • Most commonly lesions appear on head, neck and legs
  • Botryomycosis

Bacterial Pododermatitis


Systemic Bacterial Infections

  • Salmonellosis
    • Capillary dilatation and congestion -> cyanosis of external ears and abdoman
    • Thrombosis -> necrosis of extremities
  • Erysipelas in pigs
    • Caused by Erysipelothrix rhusiopathiae
    • Vasculitis, thrombosis, ischaemia -> cutaneous lesions - firm, raises, rhomboidal pink to dark purple areas
  • Clostridium novyi
    • Severe cellulitis, toxaemia and death of young rams during breeding season (due to traumatised heads) - 'big head'
  • Streptococcus equi
    • In horses
    • Immune complex vasculitis -> purpura
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