[Formation of donor strains of enteropathogenic Escherichia, serogroups O112ac, O129, O143, and Sh. boydii 8 using R-plasmids].

: The possibility of the formation of enteropathogenic Escherichia and Shigella donor strains by means of R-plasmids RP4 and RPI-2 with thermosensitive replication was studied. The donor strains of E. coli, serogroups O112ac, O129, O143, and Sh. boydii 8 were thus obtained; these strains had the above-mentioned plasmids integrated into their chromosome, and in the process of conjugation they transferred plasmid and chromosomal genes to E. coli, K12 and O129, with the effectiveness 10(5)--10(8). Such donor strains may probably be used for studying the mechanisms of the formation of new enteropathogenic Escherichia and Shigella biovars and for their genetic analysis.