ON THE MECHANISM OF THE DEVELOPMENT OF MULTIPLE DRUG-RESISTANT CLONES OF SHIGELLA

Abstract

The authors confirmed that strains of E. coli, which were isolated from human feces and resistant to streptomycin, chloramphenicol, tetracycline and sulfonamide, could produce the same multiple-resistant clones of Shigella by mixed cultivation. Using a single resistant strain as the donor, it was possible to transfer single resistance, such as streptomycin or tetracycline resistance.
The transfer of the resistance-factor by the mixed culture was succeseful intergenetically and interspecifically with Escherichia and Shigella. Since the transfer of resistance occurred without accompanying unselected markers, the induced resistant clones maintained the same biochemical and serological characteristics as those belonging to the sensitive recipient strain. As for the mechanism, the results obtained suggested the similarity of the transfer of resistance-factor to that of the colicinogenic factor.