Resistance of Dissociants of Gaffkya tetragena to Penicillin and Streptomycin.

ConclusionG. tetragena, strains 6007 and 10875, failed to acquire resistance to penicillin after repeated transfers in or on media containing it, nor did the procedure induce visible variation or reversion of the usual dissociant forms. Growth on streptomycin-agar increased the tolerance of each variant to 5 to 30 times the original amount of streptomycin which may be of clinical significance. There was no evidence that variant forms better fitted than the original one to grow under new adverse circumstances were either induced or purposefully developed. The change seemed to be a gradual adaptive one.