[Conjugative R-plasmids simultaneously belonging to the 2 incompatibility groups INC I zeta and INC B].

Five plasmids detected in the clinical strains of Shigella were studied. The plasmids had similar phenotypes of antibiotic resistance and allotted streptomycin and tetracycline resistance to the host cell. None of them allotted the bacterial cells with sensitivity to phages specific for the Inc groups F, N, P and I. The molecular weights of the plasmids ranged from 47 to 50 MD. The studies on the incompatibility showed that pKMR 227, pKMR 228-1, pKMR 231, pKMR 242-1 and pKMR 245 plasmids simultaneously belonged to two Inc groups: Inc I zeta and Inc B. Two plasmids, i.e. R 805a and R 861a simultaneously belonging to the two Inc groups: Inc I zeta and Inc B are described in the literature. pKMR 231 and pKMR 242-1 plasmids detected by the authors differ from them by the antibiotic resistance phenotype. The other three pKMR plasmids in addition differ from them by belonging to Fin.