The identification of Nocardia asteroides and Nocardia brasiliensis.

The identification of Nocardia asteroides, an important agent of human and animal disease, presents many difficulties. This organism is highly variable in its gross and microscopic morphology, as well as in many of its biochemical properties. Furthermore, it shares many characteristics with the closely related N. brasiliensis and various species of Streptomyces and Mycobacterium. Recently a number of investigators reviewed this problem. They proposed criteria and tests for the differentiation and identification of N. asteroides. The present study was carried out to evaluate these tests and to establish reliable and efficient procedures which would serve to identify N. asteroides and N. brasiliensis and differentiate them from other actinomycetes and mycobacteria.