抄録
Since streptomycin had been found by Waksman, various antibiotics were obtained in the field of streptomyces. They are different each others, not only in their chemical characters, but also their antibacterial spectra. Umezawa and others found a simple method of differentiating the antibiotics and confirmed that the antibiotics produced by S. fradiae are different from streptomycin and streptothricin-group substances produced by otherr species. According to the above authors, streptothricin-group substances are the antibotics which are obtained from the broth of various kinds of streptomyces other than S. griseus, extracted by the streptothricin extraction process, and to which streptothricin-fast E. coli are more resistant than the normal culture. Among streptothricin-group substances the antibiotics produced by S. fradiaeare different from the others not, aonly in their bacteriostatic effects against B. anthracis and B. subtilis, but also in their toxicity. The antibiotics of S. fradiae inhibit the growth of B. antlhracis as well as that of B. subtilis, however, the latter is more sensitive to the other streptothricin-group substances than the former. The antibiotics of S. fradiae do not show the later appearing toxicity which is common to the others. Therefore Umezawa named the antibiotics of S. fradiae as streptothricin B and the others as streptothricin A. Thereafter be noticed that streptothricin B produced by a certain strain of S. fradiae is different from that by other strains in the ratio of bacteriostatic effects to the minimal lethal doses to mice and named the one which is more non-toxic as streptothricin BI and another as streptothricin BII.
The antibiotics produced by S. fradiae were called as neomycin by Waksman, and thereafter neomycin A and B were differentiated. Streptothricin B seems to resemble neomycin. Both do not show the later appearing toxicity and inhibit widely grampositive and gram-negative bacteria. Neomycin inhibits the growth of streptomycinfast tubercle bacilli and the results of the experiments in vitro seemed to indicate the therapeutic effect against tuberculosis. Though the further clinical experiment could not confirm its practical use, the first animal experiment seems yet now to indicate some clinical usefulness. The chemical nature of streptothricin B is not yet definitely determined, therefore the relation to neomycin is not yet cleared. It will be cleared in other reports.
Among antibiotics obtained from streptomyces, streptomycin, chloramphenicol, aureomycin and terramycin are clinically effective against gram-negative diseases. As chloramphenicol and streptomycin are produced, by the pilot plant of our laboratory, their bacteriostatic effects are also studied, being compared with those of streptothricin BI and BII. In the present paper their effects in vitro are described.
