290 DISEASE CONTROL 



Some very striking results have been obtained in the treatment o£ 

 experimental tuberculosis in guinea pigs (Table 49). On the basis of an 

 arbitrarily established index of infection, microscopically determined, 

 100 represented the maximum possible amount of tuberculosis. The 

 control animals, sacrificed after 61 days, exhibited an index of 67 as 

 contrasted to 5.8 for those which had received streptomycin. In another 

 experiment, the corresponding values were 81.9 for the untreated and 

 2.8 for the treated animals. The daily administration of streptomycin 

 per pig varied from 1,387 to 6,000 mg. Two different strains of the 

 human tubercle bacillus were equally sensitive to streptomycin in vivo 

 (250). 



Streptomycin was pronounced to be "the most effective in vivo 

 tuberculochemotherapeutic agent which we have studied and which we 

 have seen reported in the literature." It has been repeatedly shown 

 that antibacterial agents active against M. tuberculosis in vitro may be 

 of little value in combating the infection in vivo; since experimental 

 tuberculosis in guinea pigs may be quite distinct from that produced by 

 the same organism in man, the application of results obtained in ani- 

 mals to its possible effect in humans is largely speculative. 



The ability of streptomycin to check and retard the normal course of 

 tuberculosis infection in guinea pigs has been confirmed. By combining 

 streptomycin and promin, it was possible to obtain results unlike any- 

 thing heretofore obtained in the treatment of experimental tuberculosis 

 infections (862). The combination was also found (1040) to have a 

 marked suppressive effect on experimental pulmonary tuberculosis in 

 mice. 



Both the toxicological and pharmacological properties of strepto- 

 mycin readily allow its use in the treatment of diseases in man. Pure 

 streptomycin, as well as many impure concentrated preparations, have 

 been given at therapeutic levels, in doses as high as 4 gm. daily, with- 

 out any unfavorable reactions. 



Blood levels following intravenous injections can be better main- 

 tained with streptomycin than with penicillin, detectable amounts of 

 the first being present for 6 hours compared with 2.5 to 3 hours for the 

 second. Following parenteral administration, most of the streptomycin 

 is excreted in the urine. It is distributed throughout the body fluids: 



