The inactivation of streptomycin by cyanate.

The reversal of the bacteriostatic action of streptomycin for certain mycobacteria as well as Escherichia coli by urea has been the subject of a preliminary note by Fitzgerald and Bernheim (1). At that time the possibility was considered that urea was being directly assimilated by the organisms. Subsequent work to elucidate the nature of this phenomenon has revealed that the agent which causes the reversal of streptomycin is most probably not urea but some product formed when urea is autoclaved in the medium. The purpose of this paper is to present the experimental evidence for this conclusion as well as information on the possible nature of the active reverser and its mode of action.