VMC 311: Systematic Veterinary Bacteriology and Mycology (2+1)

PATHOGENESIS

• Nocardia are aerobic and essentially saprophytic.
• They cause suppurative and pyogranulomatous reactions in immunocompromised hosts or animals that have been exposed to large doses of the bacterium.
• The pathogenic Nocardia survive within phagocytic vacuoles by preventing phagolysosome formation.
• This is probably due to the surface lipids as Nocardia species have a cell wall similar to the mycobacteria.
• Other cell wall lipids may provoke the characteristic granulomatous reaction.
• Exudates are sanguinopurulent and can sometimes contain soft granules consisting of bacteria, neutrophils and debris.
• They lack the microstructure of the sulphur granules produced by some of the Actinomyces species.
• Diseases caused by the pathogenic Nocardia are

Species	Host (s)	Disease
Nocardia asteroides Nocardia farcinica	Dogs/ Cats Cattle	Localised cutaneous granulomatous abscesses nocardiosis Pyothorax and granulomas in the thoracic cavity Chronic granulomatous mastitis Bovine farcy in tropical regions