Loss of sulphanilamide adaptation induced by growth of Bact. lactis aerogenes in presence of proflavine

Abstract

When Bacterium lactis aerogenes becomes adapted to sulfanilamide it does not lose its resistance to the drug when subcultured in a sulfanilamide-free medium. However, a marked change in resistance can be observed by a single passage of the organism through a medium containing proflavine. In presence of a mixture of proflavine and sulfanilamide the adaptation of the cells to each drug is not hindered. Adaptation to a moderate conc. of proflavine renders the cells capable of retaining their sulfanilamide adaptation, even when exposed to much higher concs. of proflavine.