Genetic and structural insights into the dissemination potential of the extremely broad-spectrum class A beta-lactamase KPC-2 identified in an Escherichia coli strain and an Enterobacter cloacae strain isolated from the same patient in France.

Two clinical strains of Escherichia coli (2138) and Enterobacter cloacae (7506) isolated from the same patient in France and showing resistance to extended-spectrum cephalosporins and low susceptibility to imipenem were investigated. Both strains harbored the plasmid-contained bla(TEM-1) and bla(KPC-2) genes. bla(KLUC-2), encoding a mutant of the chromosomal beta-lactamase of Kluyvera cryocrescens, was also identified at a plasmid location in E.

Characterization of the chromosomal class A beta-lactamase CKO from Citrobacter koseri.

The gene bla(CKO) encoding the chromosomal class A beta-lactamase of Citrobacter koseri was cloned and sequenced. CKO was found to display only 41% identity with SED-1 from Citrobacter sedlakii and 36% with CdiA from Citrobacter amalonaticus (formerly Citrobacter diversus). No transcriptional regulator was found upstream from bla(CKO).