Molecular Diversity and Plasmid Analysis of KPC-Producing Escherichia coli
ABSTRACTThe emergence and spread ofKlebsiella pneumoniaecarbapenemase (KPC) amongEnterobacteriaceaepresents a major public health threat to the world. Although not as common as inK. pneumoniae, KPC is also found inEscherichia colistrains. Here, we genetically characterized 9 carbapenem-resistantE. colistrains isolated from six hospitals in the United States and completely sequenced theirblaKPC-harboring plasmids. The nine strains were isolated from different geographical locations and belonged to 8 differentE. colisequence types. SevenblaKPC-harboring plasmids belonged to four different known incompatibility groups (IncN, -FIA, -FIIK2, and -FIIK1) and ranged in size from ∼16 kb to ∼241 kb. In this analysis, we also identified two plasmids that have novel replicons: (i) pBK28610, which is similar to p34978-3 with an insertion of Tn4401b, and (ii) pBK31611, which does not have an apparent homologue in the GenBank database. Moreover, we report the emergence of a pKP048-like plasmid, pBK34397, inE. coliin the United States. Meanwhile, we also found examples of interspecies spread ofblaKPCplasmids, as pBK34592 is identical to pBK30683, isolated fromK. pneumoniae. In addition, we discovered examples of acquisition (pBK32602 acquired an ∼46-kb fragment including a novel replication gene, along with Tn4401band other resistance genes) and/or loss (pKpQIL-Ec has a 14.5-kb deletion compared to pKpQIL-10 and pBK33689) of DNA, demonstrating the plasticity of these plasmids and their rapid evolution in the clinic. Overall, our study shows that the spread ofblaKPC-producingE. coliis largely due to horizontal transfer ofblaKPC-harboring plasmids and related mobile elements into diverse genetic backgrounds.