Susceptibility to Kasugamycin of Escherichia coli Carrying Conjugative and Nonconjugative R Plasmids

Ten conjugative and two nonconjugative R plasmids, all of which were naturally isolated, were tested for their ability to confer epistatic susceptibility to kasugamycin upon the host Escherichia coli . All of the conjugative plasmids, which belonged to various incompatibility groups, conferred a plasmid-determined epistatic susceptibility to kasugamycin upon the host cells, whereas the nonconjugative plasmids did not.