Nocardia asteroides as a cause of pneumonia in a buffalo calf.

Pulmonary nocardiosis has been described in a four-month-old male buffalo calf (Bubalus bubalis) with a history of respiratory distress lasting ten days. Microscopic examination of tissue imprints from the infected lungs revealed numerous Gram-positive, acid-fast, fine, branched, filamentous organisms which were morphologically identical with those of Nocardia spp. Cultures of pneumonic lung specimens on plain Sabouraud medium yielded pure growth of Nocardia asteroides at 37 degrees C. Lungs from ten healthy buffalo gave negative results for bacteria, suggesting that N. asteroides does not occur as a commensal in the pulmonary tissues. Epidemiological investigation established the source of infection in the immediate environment of the animal. It is emphasised that N. asteroides may be considered to be a respiratory pathogen and should be included in differential diagnosis of pulmonary diseases.