Neomycin in Experimental Tuberculosis of Guinea Pigs

Twenty-one days after infection with virulent human tubercle bacilli 10 guinea pigs were started on treatment with neomycin as follows: 2,000 units twice daily for 6 days, 4,000 units twice daily for 20 days, 6,000 units twice daily for 24 days and finally 8,000 units twice daily for 27 days for a total of 77 days of treatment. Six other animals similarly infected were treated with 6 mg. of streptomycin daily for 77 days and 10 untreated animals served as controls. When all the animals, including the controls, were killed after the treatment period there was found to be very little grossly evident disease in the animals treated with streptomycin and in those treated with neomycin in contrast to the extensive tuberculous involvement in the untreated animals. Microscopic evidence of healing such as fibrosis and calcification in tissues from the animals treated with neomycin indicated that this antibiotic was capable of effecting a reversal of the progressive tuberculosis that was present when treatment started. The effect of neomycin was not as great as that produced by streptomycin in the doses used. Preliminary observations indicate that neomycin is effective against experimental infections due to streptomycin-resistant tubercle bacilli. The kidneys from animals treated with neomycin reveal small lesions in the cortex characterized by tubular degeneration and cellular infiltration. The results reported here warrant further study of this antibiotic.