[Incompatibility properties of pKMR plasmids determining antibiotic resistance and the capacity to produce colonization antigen]. / Izuchenie svoistv nesovmestimosti pKMR-plazmid, opredeliaiushchikh ustoichivost' k antibiotikam i sposobnost' produtsirovat' antigen kolonizatsii.

pKMR207-1, pKMR208-1, pKMR209, pKMR210 and pKMR212 plasmids controlling simultaneously antibiotic resistance and capacity for synthesis of the colonization antigen were detected in wild strains of E. coli of various serotypes. The properties of compatibility of plasmids pKMR to each other and their attitude to the known incompatibility groups were studied. It was shown that pKMR207-1, pKMR208-1, pKMR210 and pKMR212 plasmids were incompatible. These plasmids had the incompatibility properties with respect to R388 (Inc FI) plasmid and probably belonged to the incompatibility group Inc. FI. pKMR209 plasmid was compatible with pKMR207-1, pKMR208-1, pKMR210 and pKMR212 plasmids and belonged to another incompatibility group.

[Physicochemical properties of the pKMR plasmids controlling antibiotic resistance and the capacity to produce colonization antigen]. / Izuchenie fiziko-khimicheskikh svoistv pKMR-plazmid, kontroli-ruiushchikh antibiotikorezistentnost' i sposobnost' produtsirovat' antigen kolonizatsii.

KMR plasmids controlling antibiotic resistance and the capacity for production of the colonization antigen were identified in wild strains of E. coli (026, 0126, 0124) and S. sonnei isolated from patients with acute intestinal diseases. The strains of E. coli 026 and E. coli 0126 carried p KMR207-1 plasmid determining resistance to chloramphenicol and tetracycline and the adhesive properties. The molecular weight of the plasmid is 98 mD. The strain of S. sonnei carried p KMR 208-1 plasmid responsible for resistance to streptomycin, chloramphenicol and tetracycline and the adhesive properties. The molecular weight of this plasmid is 98 mD. The resistance to streptomycin and tetracycline and the capacity for the synthesis of the colonization antigen in E. coli 0214 was controlled by p KMR209 plasmid with the molecular weight of 2.66 mD. The restriction analysis suggests that p KMR207a-1 and p KMR 207b-1 plasmids detected in E. coli of different serotypes were identical, since they could be broken with BamH1 endonuclease into equal numbers of fragments similar by their molecular weights. p KMR207-1 and p KMR208-1 plasmids differed in their sensitivity to BamH-1 endonuclease. However, they were broken into 6 fragments similar by their molecular weights. p KMR207-1 and p KMR208-1 plasmids are probably closely related but not identical.

[Characteristics of new pKMR-plasmids detected in natural strains of Enterobacteriaceae]. / Kharakteristika novykh pKMR-plazmid, obnaruzhennykh u prirodnykh shtammov énterobakterii.

pKMR-plasmids controlling the antibiotic resistance and adhesive properties were isolated from clinical strains of E. coli O26 and O124, and Sh. sonnei. Two of them, i.e. pKMR 207 and pKMR 208 were conjugative. On conjugation they jointly transferred the features of the antibiotic resistance and capacity for production of the colonization antigen. The studies on transformation of E. coli K 12 802 with the plasmid DNA of E. coli O124 showed that the antibiotic resistance and colonization properties in E. coli O124 were controlled by the nonconjugative plasmid pKMR 209. It was found that plasmids pKMR 207 and pKMR 208 had the fi(-)-phenotype. None of the plasmids allotted the host cells sensitivity to the donor specific phages of the incompatibility groups F, N, P, W, and I. Probably, the plasmids did not belong to these incompatibility groups. When the cells of E. coli K 12 802 were transformed with the plasmid DNA of the wild strain to the hemolytic strain of S. typhimurium with multiple antibiotic resistance, 3 pKMR 210 plasmids with different markers of the antibiotic resistance were detected in the transformants. One of the plasmids controlled both the drug resistance and the capacity for production of hemolysin. The ability of the detected pKMR plasmids to inhibit fertility and relation to the donor specific phages was studied.

[Changes in the nature of the sensitivity of an E. coli M strain carrying Inc-group R plasmids, to coliphages T3 and T7]. / Izmenenie prirody chuvstvitel'nosti shtamma E. coli M, nesushchego R-plazmidy nekotorykh Inc-grupp, k koli-fagam T i T7.

After the transfer of prototype plasmids R6K (IncX), R387 (IncK), R27 (IncH1) and T (IncN) to E. coli M nalr the appearance of histidine-dependent mutants (R27, T), histidine-leucine-dependent mutants (R6K), methionine-proline-dependent mutants (R387) was observed among the resulting transconjugates. The mutations of E. coli M nalr R+ cells induced by the introduction of the plasmids were accompanied by the transformation of the cells from the S-form into the R-form. In contrast to the prototrophs E. coli M nalr, the auxotrophs carrying plasmids R6K, R27, T acquired sensitivity to phage T7, and the methionine-proline-dependent mutant became sensitive to phages T and T7. The above-mentioned plasmids rendered E. coli M cells capable of synthetizing the donor pili. But the adsorption of phages T3 and T7 on the auxotrophic cells, both with and without plasmids, occurred due to their interaction with the cell-wall receptors.