Nocardia asteroides
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- 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