title: [Group of derepressed pKMR plasmids found in wild strains of Shigella].
abstract: A group of derepressed (drd) R plasmids was identified in 3 clinical isolates of Shigella, i. e. Sh. flexneri 1b, Sh. flexneri 3c and Sh. sonnei resistant to ampicillin (Ap), streptomycin (Sm), tetracycline (Tc), chloramphenicol (Cm), kanamycin (Km) and sulfathiazole (Su). The plasmids were designated as pKMR 202-2 (Sm, Tc, Cm, Km, Su), pKMR 203-3 (Ap, Tc, Cm, Su), pKMR 204--2 (Sm, Km, Su), pKMR 204-3 (Ap, Sm, Cm, Km, Su), pKMR 204-4 (Ap, Sm, Km, Su), pKMR 204-5 (Km, Su), pKMR 204-6 (Ap, Sm, Tc, Cm, Km, Su) and pKMR 204-7 (Sm, Tc, Cm, Km, Su). All of the plasmids were transferred with the R- -cells of E. coli in 5 minutes at a frequency of 2 . 10(-6) to 4 . 10(-5) and had the Fi+  phenotype. None of them except pKMR 203-2 transferred sensitivity to F- donor-specific phages (f2 and Q beta) to the E. coli cells. The plasmids had neither capacity for maintaining multiplication of phages Ike and PR4 possessing the donor-specific properties with respect to the Inc N-, Inc P- and Inc W-plasmids. Therefore, the pKMR plasmids do not belong to these incompatibility groups. It should be noted that several plasmid variants (2--6) were isolated from every of the Shigella strains studied. Since they were stable in the cells and could be transferred separately on conjugation it was concluded that each combination was presented by the R factors belonging to different Inc-groups.
mesh_terms: D003227:Conjugation, Genetic; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000235:genetics; D005819:Genetic Markers; D010641:Phenotype; D010957:Plasmids; D011815:R Factors; D012760:Shigella / Q000235:genetics*; D012763:Shigella flexneri / Q000235:genetics; D012764:Shigella sonnei / Q000235:genetics
chemical_list: D005819:Genetic Markers
vernacular_title: Gruppa depressirovannykh pKMR-plazmid, vyiavlennykh u dikikh shtammov Shigella.