Cortisone injection tests were made to check infections due to Corynebacterium and Tyzzer's organism among mouse breeding colonies and the following results were obtained.
A single injection of 2.5 to 5 mg cortisone was effective to check the both infections and the symptoms in resulting fatal disease or the lesions in killed animals after cortisone injection were perfectly analogous to those observed in the natural infections. A part of cortisone-injected mice died of the infection within 2 weeks after injection, although most of infected animals were detected when killed at the end of the observation. The incidence of the both infections was much higher in cortisone-treated young animals than in non-treated ones or in retired breeder animals from the same breeding colony. Since maintainance for a certain period in the laboratory, where contamination was possible, seemed to render animals resistant to cortisone injection test, it might be desirable to make the test on arrival at the laboratory.
