Nocardia asteroides

• Found in soil and decaying vegetation - saprophytic
• Opportunistic infection of immunocompromised animals
• Infection via inhalation, wounds or teat canal; also ingestion
• Causes granulomatous lesions in animals
• Canine nocardiosis:
  • Thoracic, cutaneous and disseminated forms
  • Cutaneous pyogranulomas: ulcers or granulomatous swellings with discharging fistulae
  • peritonitis
  • pleuritis and pyothorax with fever, anorexia and respiratory distress
  • Disseminated lesions
  • Treat with appropriate systemic antibiotics for 6 weeks
• Cattle: chronic mastitis; abortion
• Pigs: abortion
• Sheep, goats, horses: wound infections; mastitis; pneumonia
• Survives and multiplies in macrophages
• Superoxide dismutase and catalase as well as a thick peptidoglycan wall prevent activity of phagocytes
• Chronic, progressive disease
• Positive modified Ziehl-Neelson
• Culture on blood agar and incubate under aerobic conditions at 37 degrees centigrade for 10 days
• White, powdery colonies, adherent to the agar appear after 5 days
• Subculture onto Sabouraud dextrose agar yields wrinkled, orange colonies
• Lesions difficult to treat due to resistance of organisms to many antimicrobials (e.g. penicillins)
• Cell-mediated immunity required