THE MICROBIOTICS — MCDONNELL 453 



STREPTOTHRICIN AND STREPTOMYCIN 



However, another new antibiotic which is already in the clinical 

 research stage of development is streptothricin. This substance is 

 derived from A. lavendulae and is effective against both gram-positive 

 and gram-negative organisms. It possesses the properties of an or- 

 ganic base. Streptothricin is antimicrobic rather than merely anti- 

 bacterial for it has shown value against various pathogenic fungi and 

 higher forms. In addition to equaling the value of penicillin against 

 gram-positive organisms (with the exception of streptococci), it has 

 a significant value against such gram-negative organisms as the colon- 

 typhoid and salmonella groups. Other than use in the treatment of 

 infected wounds and burns, it has a limited future. 



Streptomycin, a closely related compound, is similar in activity and 

 has been shown to have far less toxicity. Developed by Waksman 

 and his associates at the New Jersey Agricultural Experiment Station, 

 streptomycin is derived from cultures of Actinomyces griseus. It has 

 shown remarkable properties in combating both gram-positive and 

 gram-negative organisms, particularly against hitherto resistant bacil- 

 lary conditions of the latter group. This new drug has been studied 

 by Herrell and Heilman, of the Mayo Clinic, and by Keimann and 

 others at Pennsylvania. 



Effective against Klebsiella pneumoniae, Friedlander's infection, 

 mixed bacillary and salmonella infections, and in particular against 

 B. tularense of tularemia, streptomycin has proved exceedingly valu- 

 able in the eradication of Eberthella typhosa in typhoid fever. In early 

 reports based on laboratory in vivo experiments and on remission of 

 lesions in clinical treatment of Mycobacterium tuberculosis infections, 

 streptomycin has been found to be a valuable agent. It has also given 

 early promise in treatment of veterinary infections such as fowl 

 typhoid and brucellosis. 



Streptomycin is not a replacement for penicillin, but will be a valued 

 supplement to that drug and to the sulfonamide chemotherapeutic 

 agents. It has great promise as a therapeutic agent of the future. 



As far as the related antibiotics are concerned, three substances are 

 now recognized as valuable in the treatment of human infections. One 

 is derived from soil bacteria, the other two from molds. Tyrothricin 

 has sufficient value to be retained as a therapeutic agent for immediate 

 nontissue penetration contact bactericidal action, particularly for op- 

 erational usage. Streptomycin is already proved of value for its effec- 

 tiveness against the gram-negative organisms. Penicillin will still 

 remain the drug of greatest promise, at least until some as yet undis- 

 covered substance appears to displace it. 



