178 Perspectives in Microbiology 



proves to be streptomycin, chloramphenicol, or a tetra- 

 cycline. A fresh approach and a new orientation may prove 

 necessary if these screening programs are to be of con- 

 tinuing productivity. Whether that fruitful new approach 

 involves an intensive study of the metabolic pathways by 

 which the antibiotics are produced; whether the screen- 

 ing program itself could be profitably modified, for ex- 

 ample, by greater emphasis on protozoa and viruses; or 

 whether the chemical modification of known antibiotics, 

 with a view to altering their antibacterial spectrum or 

 reducing their toxicity, deserves further exploration; this 

 is the multiple-choice problem with which the pharma- 

 ceutical industry has been faced for some years. 



We as microbiologists cannot share the satisfaction of 

 the physician and of the drug house in their joint past ac- 

 complishments. However reluctantly, we must admit that 

 the striking chemotherapeutic advances of the past decade 

 have resulted from screening programs. There has been 

 no comparable progress in the development of new agents 

 on the basis of a priori considerations, or even in our un- 

 derstanding of the cellular effects and selective cytotoxicity 

 of the known agents. This is the intellectual challenge 

 of the antibiotics. Even on a pragmatic level, it is possible 

 that in this instance also, to paraphrase the title of Flex- 

 ner's famous essay, the slow and laborious pursuit of ap- 

 parently useless knowledge for knowledge's own sake may 

 in the long run prove even more rewarding than the 

 screening programs have proved to date. 



