[Transmissivity of the various R factors found among E. coli cultures circulating under natural conditions]. / Transmissivnost' razlichnykh R-faktorov, obnaruzhennykh sredi kul'tur E. coli, tsirkuliruiushchikh v estestvennykh usloviiakh

Transmissivity of drug resistance in wild strains of E. coli was shown to be determined not only by the presence of the transmissive factor and r-determinants in the microbial cell, but also by the functional activity of the R-factor. The capacity of the R-factor for transmission depended to a certain extent on the number of the r-determinants in the R-factor and the presence of various r-determinants in the R-factor.

[Transmissivity of drug resistance in Salmonella]. / Transmissivnost' lekarstvennoi ustoichivosti u Sal'monell

The experiments showed that among 110 Salmonella strains resistant to 1 or more antibiotics 54.5 per cent of the cultures transfered their resistance to E. coli when grown in vitro. The frequency of the transmissive drug resistance in Salmonella was directly proportional to the number of r-determinants in R-factor. The cultures resistant to ampicillin and kanamycin proved to be the most competent donors.