Episome-mediated transfer of drug resistance in Enterobacteriaceae. III. Transduotion of resistance factors.

Watanabe, Tsutomu (Keio University, Tokyo, Japan), and Toshio Fukasawa. Episome-mediated transfer of drug resistance in Enterobacteriaceae. III. Transduction of resistance factors. J. Bacteriol. 82:202-209. 1961.-Transmissible multiple drug resistance of Enterobacteriaceae, which includes resistance to streptomycin (SM), chloramphenicol (CM), tetracycline (TC), and sulfonamide (Su), was found to be transduced in the systems of Salmonella typhimurium strain LT-2 with phage P-22 and Escherichia coli strain K-12 with phage P1kc. No linked chromosomal markers to the resistance factors have so far been found in the substrains of K-12. The transductants of K-12 were all found to be able to transfer their resistance factors by conjugation, whereas a majority of those of LT-2 could not transfer their resistance factors by conjugation. The resistance factors were segregated rarely in K-12 and consistently in LT-2. Defective resistance factors could be transferred by conjugation to the transductants of LT-2. The transductants thus made resistant to the four drugs were able to transfer only the resistance factors which had been introduced by conjugation and none of those which had been transduced. The patterns of segregation of the resistance factors by transduction suggested that they are located in the following sequence; Su-----Sm-----Cm-----Tc, and they were assumed to be carried by an episome "resistance transfer factor" which is considered to be located at the distal end of Tc.