Sensitivity and Resistance to Spectinomycin in Escherichia coli

Inhibition of growth and division of Escherichia coli by spectinomycin is reversible, and the kinetics of its interference with deoxyribonucleic and ribonucleic acid synthesis may be interpreted as secondary effects of inhibition of protein synthesis on the ribosome. Spontaneous mutations to spectinomycin resistance occur in E. coli K-12 at a rate of about 2 x 10(-10). Resistance is transducible with a discrete lag in phenotypic expression, and the kinetics of its development is about the same as that for streptomycin resistance. All spectinomycin-resistant mutants tested contain resistant ribosomes, and all map in a locus (spc) counterclockwise to and 70% cotransducible with the classical str locus. Differences in the residual drug sensitivity of various spectinomycin-resistant mutants, and of their ribosomes, indicate the existence of more than one phenotypic class of resistance.