Kanamycin was first described by Umezawa et al. in 19571; it is produced by Streptomyces kanamyceticus.ChemistryThe crystalline sulfate of kanamycin is water-soluble, alcohol-insoluble, and basic. It is a very stable compound with less than 10% loss after autoclaving for one hour at 120 C; it is stable over a pH range of 2 to 11. Cron and his co-workers2have determined that kanamycin consists of two amino sugars linked glycosidally to 2-deoxystreptamine, with the structural formula shown in Figure 1. This structure resembles that of neomycin and has some similarity to streptomycin.Paper chromatography of kanamycin preparations reveals a second antibiotic, kanamycin B. Kanamycin B exhibited more toxicity than kanamycin A in animal studies3and is present to the extent of only 2% to 3% in later preparations of the drug.Microbiological Studies1.Spectrum.—In vitro, kanamycin is active against a variety