REVERSAL BY COMPLEX NATURAL MATERIALS OF GROWTH INHIBITION CAUSED BY ANTIBIOTICS

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Abstract
A spread plate procedure has been devised to show that 4-8 times the concn. of penicillin, streptomycin, aureomycin, chloramphenicol, terramycin, and bacillin are required for complete inhibition of Escherichia coli in the presence of small amts. (100 to 1000 [mu]g./ml.) of complex organic supplements than in their absence. This is interpreted as a reversal of antibiotic inhibition by one or more substances in the complex mixtures. Cysteine and cystine had no effect under the conditions employed; reversal activity of the complex materials is not the result of destruction of the antibiotic. Characteristics of the spread plate procedure as applied to this problem are given, and some features of the counteraction of inhibition by antibiotics are descr. Inadequacies of liquid cultures for work of this kind are discussed.