Serological study of nocardia by using mycobacterial precipitation reference systems.

Forty-six nocardia strains and ten strains labeled "Mycobacterium" were analyzed with the comparative immunodiffusion technique, employing as reference material nine mycobacterial precipitation systems, each one representing a different species. Three precipitinogens were common for many of the tested strains and the mycobacterial reference strains. The serological analyses indicated the possibility of differentiating two groups within Nocardia depending on the characteristics of one of the common precipitinogens. Five of eight tested Nocardia farcinica strains showed a serologically close relationship with the mycobacteria and might be regarded as belonging to this genus. The "M." pellegrino and "M." rhodochrous strains, however, did not react with the antimycobacterial sera to a higher degree than did the tested nocardia strains.