Botryomycosis

• Caused by Staphylococcus aureus
• Occurs in horses and pigs usually due to wounds
• Lowgrade persistent infection -> granulomatous lesions
• Grossly:
  • Hard nodules with fibrous capsule in muscles
  • Contain yellow-brown pus and granules
• Histologically:
  • Encapsulated granulomatous lesions
  • Central club colonies
  • Staphylococci are present

• • Granulomatous dermatitis caused by nonfilamentous bacteria
  • Usually Staphylococcus aureus
  • Small, yellow granules are formed - sulfur granules
    • Central bacteria surrounded by homogeneous eosinophilic material
• Filamentous bacteria can also cause granulomas
  • E.g. Actinomyces and Nocardia, Actinobacillus