Kanamycin-resistance mechanism of Pseudomonas aeruginosa governed by an R-plasmid independently of inactivating enzymes.

We have isolated a strain K-Ps 102 with Rplasmid resistant to the 5 antibiotics, tetracycline (TC), chloramphenicol (CP), streptomycin (SM), sulfonamide (SA) and kanamycin (KM), from clinically isolated Pseudomonas aeruginosa strains.1) The resistance mechanisms of this Rplasmid kR102 have been studied with TC, SM, and CP2`4). The results suggest that a decrease of cell permeability for the respective drugs contributes to the resistance. This report deals with the mechanism of KM-resistance by the R-plasmid, kR102, in Pseudomonas aeruginosa. A rifampicin (RFP) resistant mutant, K-Ps 47 RFP sensitive to the 5 antibiotics described above was used as an R-strain. A conjugant, K-Ps 47 RFP (kR102), was obtained from K-Ps 47 RFP by mating with K-Ps 102. KM-inactivation by cell free extracts was examined as follows: 0.3 nil of cell free extract (30 mg protein/ml), 0.1 nil of 40mt ATP, 0.1 ml of 2 m\ CoA, 0.1 nil of 1 mM KM, and 0.4 nil of TMK solution (0.06 M KCI, 0.01 M magnesium acetate, and 6 mm 2-mercaptoethanol dissolved into pH 7.8 Tris-HCl buffer solution) were mixed and allowed to react at 37'C for 24 hours,