Chloramphenicol-sensitive and-insensitive phases of the lethal action of streptomycin.

Hurwitz, Charles (Veterans Administration Hospital, Albany, N.Y.) and Carmen L. Rosano. Chloramphenicol-sensitive and -insensitive phases of the lethal action of streptomycin. J. Bacteriol. 83:1202-1209. 1962.-If chloramphenicol is added to sensitive Escherichia coli cells at the same time as streptomycin, the lethal effect of the latter drug is prevented. If the cells receive a prior exposure to streptomycin before the addition of chloramphenicol, the bacteria are then susceptible to killing by streptomycin in the presence of chloramphenicol. These results are interpreted to mean that the lethal action of streptomycin can be divided into chloramphenicol-sensitive and chloramphenicol-insensitive stages. It is proposed that during the chloramphenicol-sensitive stage, a streptomycin-initiated protein synthesis occurs, and that this protein synthesis must precede the actual killing by streptomycin. Inorganic phosphate has no effect on the chloramphenicol-sensitive phase, but does prevent killing by streptomycin. Evidence is presented arguing against the formation of a leaky permeability barrier as being the primary cause of death of cells exposed to streptomycin.