Abstract
The number of viable Escherichia coli in a young, actively growing culture is decreased approximately 99.9 per cent by a 30 second exposure to 25 phig. streptomycin/ml. The injury induced by the antibiotic is only potentially lethal, however, and may be reversed by subculture within 5 minutes into fresh culture medium, NH(4)NO(3), NH(4)Cl, (NH(4))(2)HPO(4), NH(4) citrate, and NH(4) tartrate. Subculturing into water, glucose, or MgSO(4) results in a more marked decrease in the number of viable organisms. In KNO(3), NaNO(3), K(2)HPO(4), and Na(2)SO(4) solutions reversal occurs first, followed by a rapid decrease in viability. True reversal of the streptomycin injury takes place, as demonstrated by the rapid rate of recovery to the viable count of the original culture. Development of resistance has been eliminated as the cause of regrowth since the streptomycin sensitivity of recovered cultures remained the same as that of the original culture. The use of water as diluent for viability determinations potentiates the lethal effect of streptomycin activity. Several compounds, at various dilutions, substituted for water as the diluent gave rise to four types of responses, group I, NH(4)NO(3), NH(4)Cl, KNO(3), NaNO(3), Ca(NO(3))(2), showed complete reversal of the streptomycin injury at all levels of the salts tested, from 0.01 to 0.5 M concentrations. Group II, NaCl and K(2)HPO(4) showed complete reversal at 0.03 and 0.1 M. Group III, glucose and urea allowed complete reversal at 0.5 M. Group IV, glycerol and glycerine showed no reversal at 0.5 M concentration. The reversal of the streptomycin injury to young actively growing bacteria is suggested as a tool for studying the pathology of the injury to the cells.
Highlights
It has been reported that the inhibitory action of streptomycin on bacteria can be counteracted by culture medium components, pH, salts, etc. [1,2,3,4]
This paper reports on the results of an investigation, based on the above principles, of the antibiotic activity of streptomycin on Escherichia coli, and the process of the reversal of this inhibition
Using a young actively growing culture of E. coli, it is possible to study the activity of streptomycin
Summary
It has been reported that the inhibitory action of streptomycin on bacteria can be counteracted by culture medium components, pH, salts, etc. [1,2,3,4]. Growth may have resulted from [1] selection of a few resistant organisms, [2] adaptation of the majority of cells in the original inoculum to alternate metabolic pathways, or [3] a general stimulatory effect of the added test compound which would increase growth of normal cells as well as that of cells exposed to streptomycin. Utilized by the cell for the immediate resumption of normal activity The effects of such an injury, and the activity of various substances in reversing the injury, can be detected in several ways; e.g., changes in viable cell counts, or metabolic activity. This paper reports on the results of an investigation, based on the above principles, of the antibiotic activity of streptomycin on Escherichia coli, and the process of the reversal of this inhibition
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