Pathogenicity of Nocardia transvalensis for laboratory mice.

Nocardia transvalensis was found to be virulent for laboratory mice both by intraperitoneal and intravenous routes of inoculation, the latter route producing a more progressive and disseminating infection. Cortisone administration was found to enhance the susceptibility of mice, the LD50 for the cortisone treated mice being five times less than that for the untreated animals. In the tissues of cortisone treated mice, N. transvalensis grew as dispersed filaments with coccobacillary forms or sometimes their loose aggregates, whereas in normal animals granule formation was a conspicuous feature. The pathogenicity of N. transvalensis is compared with that of N. asteroides, N. brasiliensis and N. caviae from published reports.