Abstract
Summary
Under standard test conditions, raising the concentration of tryptone from 0.50% to 1.0%, in a medium containing only tryptone and water, raised the minimum inhibiting concentration of streptomycin from 0.036 units/ml to 0.084 units/ml. The fur-their addition of glucose to the medium increased the minimum inhibiting concentration to a lesser, but nevertheless, definite degree.
The minimum inhibiting concentration of streptomycin in an enriched broth containing sodium glycollate was about 10 times greater than that in 0.75% tryptone. The substitution of sodium thioglycollate for sodium glycollate further greatly increased the MIC. This additional interference by sodium thioglycollate was observed to decrease as the broth aged (and hence as the thioglycollate was oxidized). Since thioglycollate per se is said to cause no significant destruction of streptomycin, it is proposed that its interfering action may be due to its role in reducing the oxidation-reduction potential of the medium and that perhaps streptomycin interferes more with the aerobic than anaerobic metabolism of the test organism.
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