Mosaic Structure of p1658/97, a 125-Kilobase Plasmid Harboring an Active Amplicon with the Extended-Spectrum β-Lactamase Gene bla SHV-5

Escherichia coli isolates recovered from patients during a clonal outbreak in a Warsaw, Poland, hospital in 1997 produced different levels of an extended-spectrum β-lactamase (ESBL) of the SHV type. The β-lactamase hyperproduction correlated with the multiplication of ESBL gene copies within a plasmid. Here, we present the complete nucleotide sequence of plasmid p1658/97 carried by the isolates recovered during the outbreak. The plasmid is 125,491 bp and shows a mosaic structure in which all modules constituting the plasmid core are homologous to those found in plasmids F and R100 and are separated by segments of homology to other known regions (plasmid R64,Providencia rettgeri genomic island R391,Vibrio cholerae STX transposon,Klebsiella pneumoniae orE. coli chromosomes). Plasmid p1658/97 bears two replication systems, IncFII and IncFIB; we demonstrated that both are active inE. coli . The presence of an active partition system (sopABC locus) and two postsegregational killing systems (pemIK andhok/sok ) indicates that the plasmid should be stably maintained inE. coli populations. The conjugative transfer is ensured by the operons of thetra andtrb genes. We also demonstrate that the plasmidic segment undergoing amplification contains thebla SHV-5 gene and is homologous to a 7.9-kb fragment of theK. pneumoniae chromosome. The amplicon displays the structure of a composite transposon of type I.