Abstract
Summary
1. Differences in the vitamin requirements of susceptible strains of S. mitis, their artificially-induced resistant variants and a naturally-resistant S. fecalis, have been determined. 2. The greatest difference was in the PGA requirements, the mitis strains grew in its absence; the resistant mutants required PGA. 3. The induced resistance of the trained S. mitis strains appears to be the same as that of the natural resistance of S. fecalis, and may be due to the loss of ability to synthesize PGA, the synthesis of which is inhibited by sulfonamides.
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