A novel integron-like element carrying the metallo-beta-lactamase gene blaIMP.

A plasmid-mediated metallo-beta-lactamase gene was cloned from a carbapenem-resistant Serratia marcescens strain, AK9373. The metallo-beta-lactamase gene was identical to the blaIMP, and it was located in the space between an integrase-like gene and an aac(6')-Ib-like gene. The deduced amino acid sequence for the putative integrase gene showed considerable identity (60.9%) to that of the Escherichia coli integrase reported. Sequences similar to the GTTRRRY and an atypical 59-base element containing a 67-bp inverted repeat sequence, which were peculiar to the integrase-dependent recombination, were also conserved in the flanking regions of the blaIMP gene. These findings imply that the metallo-beta-lactamase gene in S. marcescens AK9373 is carried by a novel integron-like element that is mediated by a transferable large plasmid.