Comments on bacterial resistance to streptomycin.

Shortly after streptomycin was introduced in the treatment of tuberculosis, two major obstacles to its value as a therapeutic agent became apparent. These were, vestibular damage and development of bacterial resistance. With the reduction in the daily dosage from 2 gm. and higher, to 1 gm. and later to 0.5 gm., serious vestibular damage has been eliminated. However, development of bacterial resistance, which is apparently due to duration of treatment rather than to dosage, remains for the present the most serious threat to successful streptomycin therapy in tuberculosis. With the appearance of resistant forms of tubercle bacilli, streptomycin ceases to be an effective therapeutic agent not only for the individual patient but also for those to whom he may transmit the disease. Youmans and Wffliston’ found that when a group of mice were injected intravenously with 0.1 mg. of a culture of tubercle bacilli isolated from a patient with pulmonary tuberculosis, streptomycin bad a marked suppressive effect on the infection produced in the animals. On the other hand when a group of mice were injected in the same manner with a culture of tubercle bacilli from the same patient after he was treated with streptomycin, the infection resulting from it was uninfluenced by the drug. Bogen2 related the case of a nurse who contracted tuberculosis while working with streptomycin treated patients. Tubercle bacilli recovered from this case were resistant to 1000 micrograms per cc. on original isolation. It is obvious why the study of bacterial resistance to streptomycin and specifically the search for measures to prevent it are occupying a very prominent place in this field of investigation. The theory behind the development of bacterial resistance to streptomycin is based on the knowledge that probably every case of tuberculosis harbors different varieties of tubercle bacilli. By