288 DISEASE CONTROL 



other pathogens. Mycobacteria are readily inhibited by both strepto- 

 thricin (1029) and streptomycin (232, 831). Different strains of M. 

 tuberculosis vary greatly in their sensitivity to the same substance. The 

 same is true of the sensitivity to streptomycin of different strains of 

 Erysifelothrix and various saprophytic and parasitic actinomycetes. 



When given parenterally, streptomycin, injected daily in doses of 

 50,000 units (50 mg. of pure base) per kg, for one month, was well tol- 

 erated by mice, rats, and monkeys. Injected subcutaneously, 100 \\g 

 gave protection to mice against 10,000 lethal doses of the pathogen. 

 Feces of mice fed streptomycin was sterile as far as lactose-fermenting 

 bacteria were concerned j the total population was considerably reduced. 

 Seventy per cent of the streptomycin was excreted in the urine in 5 to 6 

 hours. In order to maintain proper blood concentration it has to be 

 administered, therefore, by frequent intramuscular injections or by 

 continuous intravenous drip (746, 791, 795). 



Streptomycin was found to be effective in the treatment of a variety 

 of experimental infections caused by various gram-negative bacteria, 

 including Br. abortus (478), Sh. galUnarufn (478), S. schottmulleri 

 i795)y P- tularensis (397), the Friedlander bacillus or Klebsiella 

 (398), Z). pneumoniae (y<^5), M. tuberculosis (249), and a number of 

 others, especially the organisms commonly found in urinary infections 

 (401). In a comparative study of several human strains of M. tuber- 

 culosis, the bacteriostatic concentration of streptomycin was shown to 

 vary from 0.095 to 0.78 Mg per ml.j the effect was not influenced 

 greatly by either the number of organisms or the presence of human 

 plasma (Table 46). The bactericidal action of streptomycin upon 

 human tubercle bacilli was slight as compared with its bacteriostatic 

 action, nearly lOO pg/ml. being required to kill o.i mg. of virulent 

 bacterial cells (1039). 



In the treatment of mice infected with the tularemia organism 

 (Table 47), the controls died within 96 hours after inoculation, those 

 receiving 1,000 units or i mg. of pure streptomycin daily, for 10 days, 

 survived J smaller amounts of streptomycin gave incomplete protection 

 (397). Infections caused by various other organisms, such as Borrelia 

 novyi and Leftosfira icterohaemorrhagiae (Table 48), can also be 

 treated with streptomycin (399). Streptomycin is not effective in the 



