118 



NATURE, FORMATION, AND ACTIVITIES 



tion of virus vaccines has made possible cer- 

 tain special forms of prophylactic therapy. 



Problems Arising from Use of Anti- 

 biotics 



The tremendous benefits of antibiotics to 

 the human race were soon fully recognized. 

 They were lauded as the "miracle drugs." 

 The medical profession was ready to replace 

 the concept of "chemotherapy" with that of 

 "antibiotic therapy." On the other hand, 

 many persons went to the other extreme. 

 If no rapid cures for cancer or for the ^'arious 

 viral diseases were forthcoming, they tended 

 to blame the antibiotics. When of the hun- 

 dreds of thousands of cultures tested and 

 the numerous antibiotics isolated, only 20 

 or 30 found a place in practical therapy, 

 many persons felt cheated and asked for 

 more. Further, the de^'elopment of liacterial 

 resistance to some antibiotics and the unde- 

 sirable reactions occasionally produced in 

 certain patients were given undue pul)licity, 

 with the resulting designation of the anti- 

 biotics as "toxins" and "poisons" (Gale, 

 1960). 



Ciradually, howe\'ei', the undesirable char- 

 acteristics of the antil)iotics are being elimi- 

 nated through a better understanding of 

 their use. Combinations of two antibiotics, 

 such as penicillin and streptomycin, or of 

 two forms of the same antibiotic, such as 

 streptomycin and dihydrostreptomycin, or 

 of an antibiotic with a synthetic chemical 

 agent, as streptomycin with p-aminosalicylic 

 acid or with isoniazid in the treatment of 

 tuberculosis, have tended to increase the 

 effectiveness of antibiotics and decrease 

 their limitations (Lacey, 1960). New anti- 

 biotics are constantly being introduced to 

 supplement those now in use. Both the 

 physician and the patient have come to 

 recognize that every new discovery carries 

 wdth it an obligation and that no sure cure 

 can be expected, even from the most nearly 

 ideal drugs, unless their mode of action, 



their specific role in therapy, and especially 

 their limitations are thoroughly understood. 



Treatment of Plant Diseases 



The antagonistic effects of microbial 

 saprophytes upon plant pathogens were 

 recognized long before the advent of anti- 

 biotic therapy. Various bacteria and fungi 

 were utilized for the purpose of controlling 

 plant diseases. The results were not alwaj^s 

 convincing, however, and could never be 

 properly duplicated. On the other hand, 

 some of the antibiotics, such as streptomy- 

 cin, have proved to be markedly effective 

 in the treatment of \'arious bacterial dis- 

 eases of plants; and actidione, antimycin, 

 and streptomycin have found a place in the 

 ti'eatment of certain fungus diseases. A de- 

 tailed re\iew of this suljject was recently 

 published by P. Miiller (1959). 



Important Therapeutic Applications 



A list of the anti})iotics of actinomycetes 

 that ha\'e found important therapeutic ap- 

 plications is given here in order of their 

 disco\'ery : 



Actinomycins C and D, used in the treat- 

 ment of certain forms of cancer, such as 

 rhabdosarcoma and Wilms' tumor. 



Streptomycin and dihydrostreptomycin, 

 used in the treatment of tuberculosis and of 

 various infections caused by gram-negative 

 and gram-positive bacteria; also of certain 

 plant diseases caused by bacteria and a few 

 fungi. 



Chlortetracycline, oxytetracycline, and 

 tetracycline, used in the treatment of dis- 

 eases caused by various gram-posit Ia'c and 

 gram-negative bacteria, rickettsiae, and the 

 psittacosis-lymphogranuloma group of or- 

 ganisms. 



Chloramphenicol for the treatment of 

 diseases caused by gram-posit i\'e and gram- 

 negative bacteria, rickettsiae, and the psitta- 

 cosis-lymphogranuloma group of organisms. 



