Thermosensitive replication of a kanamycin resistance factor.
A strain of Proteus vulgaris isolated from the urinary tract of a patient with postoperative pyelonephritis and resistant to sulfonamide, streptomycin, tetracycline, and kanamycin (KM) was found to transfer only KM resistance by cell-to-cell conjugation. The genetic determinant controlling the transferable KM resistance was considered to be an R factor and was designated R (KM). Successive transfer of KM resistance was demonstrated also from Escherichia coli 20S0, which received the R (KM) factor, to other substrains of E. coli K-12 or Salmonella typhimurium LT-2. The transfer of the R (KM) factor was strongly affected by the temperature at which the mating culture was kept. The transfer frequency of R (KM) at 25 C was about 10(5) times higher than at 37 C. The R (KM) factor was spontaneously eliminated from the host bacterial cells when P. vulgaris was cultured at 42 C, but no elimination occurred at 25 C. This elimination of the R (KM) factor at elevated temperature was also observed when the R (KM) factor infected E. coli and S. typhimurium. On the other hand, a normal R factor could not be eliminated from the same E. coli host strain by cultivation at the higher temperature. We consider the thermosensitive transfer and the spontaneous elimination of the R (KM) factor at higher temperature to depend upon thermosensitive replication of the R (KM) factor.
D004096:Dihydrostreptomycin Sulfate / Q000494:pharmacology; D004926:Escherichia coli; D005823:Genetics; D007612:Kanamycin / Q000494:pharmacology*; D008967:Molecular Biology; D011511:Proteus / Q000187:drug effects; D012486:Salmonella typhimurium; D013444:Sulfisoxazole / Q000494:pharmacology; D013696:Temperature; D013752:Tetracycline / Q000494:pharmacology
D007612:Kanamycin; D013444:Sulfisoxazole; D013752:Tetracycline; D004096:Dihydrostreptomycin Sulfate