The Influence of Cortisone on Experimental Tuberculosis of Guinea Pigs

¹ Division of Experimental Medicine, Mayo Foundation, University of Minnesota, Rochester, Minnesota.
² Research Assistant, Mayo Foundation, University of Minnesota, Rochester, Minnesota.

Forty-eight guinea pigs were inoculated with virulent tubercle bacilli and 20 days later six were killed and found to have visible lesions of tuberculosis. The remaining animals were divided into groups as follows: 10 controls, eight treated once daily with 6 mg. of streptomycin, eight treated once daily with 2 mg. of streptomycin, eight treated once daily with 2 mg. of cortisone, and eight treated once daily with 2 mg. of streptomycin plus 2 mg. of cortisone. Treatment started on the 21st day of infection and continued for 62 days. During the course of treatment the animals given cortisone alone or in combination with streptomycin showed an average loss of weight and also a decrease of sensitivity to tuberculin in comparison to the other groups. After 62 days of treatment all animals were killed. The untreated controls and those given cortisone alone were found to have extensive tuberculous disease in the lungs, liver and spleen. There was almost complete absence of visible lesions in those given 6 mg. of streptomycin. Those given 2 mg. of streptomycin had less disease than seen in the controls. Only two of eight animals given streptomycin plus cortisone appeared to have responded beneficially. The other six had visible lesions of tuberculosis comparable to those seen in the controls. Histopathologic studies confirmed the necropsy findings. In six of the eight animals treated concomitantly with streptomycin and cortisone, the administration of cortisone appeared to have prevented the restriction and healing of the tuberculous process. Cortisone had no inhibitory effect on streptomycin in vitro.