Selman A. Waksman, Jack Frankel, Otto Graessle
1949 Journal of Bacteriology  
Among the most important properties of a new antibiotic are its toxicity to animals and its in viw activity. When this antibiotic is produced by a member of a group of organisms that has already yielded several important or promiig agents, a comparison of their respective in vivo activities and chemotherapeutic potentialities is desirable. Since neomycin (Waksman and Lechevalier, 1949) is produced by a member of the genus Streptomyce8, which has yielded such interesting and important compounds
more » ... mportant compounds as streptothricin, streptomycin, chloromycetin, and aureomycin, it is logical that the comparison should be based upon these agents, especially the first two, which were isolated in this laboratory. Neomycin differs from streptothricin and from streptomycin in its antibiotic spectrum. Although streptothricin has potential in tivo activity (Metzger et al., 1942) , its latent toxicity prevents its use as a chemotherapeutic agent. Streptomycin, on the other hand, is not very toxic (Jones et al., 1944) and is highly effective against certain gram-positive and gram-negative bacteria. To protect mice against infection with Salmonella schottmilleri and egg embryos against SalmoneUa pullorum, 50 ,g per mouse or embryo were required. Neomycin is slightly more effective against such bacteria than is streptomycin. Mice weighing 15 to 20 g require doses as low as 25 units and even 12.5 units to protect them against Staphylococcu aureus; concentrations of 100 units or less were effective against S. 8chottmiilleri. Both streptomycin-sensitive and streptomycin-resistant strains were found to be affected alike by neomycin both in tivo and in vitro (Waksman and Lechevalier, 1949) . The toxicity of neomycin to mice, when given in a single subcutaneous injection, was found to range from above 2,000 to above 5,000 units per mouse, depending on the nature of the particular lot of material and the degree of purity. Crude preparations of neomycin instilled into the eye sac of the rabbit in concentrations of 1,500 units per ml for 30 minutes produced only a mild transient irritation. No delayed toxic signs were noticed during the 7-day observation period. EXPERIMENTAL RESULTS Effect against S. aureus. The following results of detailed investigations of the in vivo activity of neomycin, as compared to streptomycin, tend to substantiate previous conclusions and enlarge the number of organisms tested.
doi:10.1128/jb.58.2.229-237.1949 fatcat:zkmgegfprjc4voegaidgtsp5em