[Analysis of carbapenem resistant plasmid isolated from Serratia marcescens].

Four nontransferable plasmids of about 28-32 kbp were isolated in 120 Serratia marcescens strains isolated from patients with urinary tract infection. All of these plasmids were tranformable in Escherichia coli, and showed a high frequency of mobilization by R9-5 plasmid of incompatibility group F II. The MICs of carbapenems were significantly lower than those of cephalosporins. This trend was more marked when MICs were determined at 10(6)cfu/ml. Based on the substrate profiles and on the effect of inhibitors of the beta-lactamase, the enzyme was classified as a class B beta-lactamase, so called carbapenemase. The carbapenem resistance genes of these 4 plasmids were cloned into vector plasmid pHSG398 using Bam H1 digestion and the size of the DNA was found to be 4.9 kb.