Characterization of the plasmid of incompatibility groups IncFII pKF727591 and Inc pKPHS1 from Enterobacteriaceae species

Background: Multiple incompatibility (Inc) groups of plasmids have been identified in Enterobacteriaceae species, but there are still quite a few sequenced plasmids that could not be assigned to any known Inc groups. Methods: One IncFIIpKF727591β plasmid p205880-qnrS and two IncpKPHS1 plasmids p11219-CTXM and p205880-NR1 were fully sequenced in this work. Detailed genomic comparison was applied to all available sequenced plasmids of IncFIIpKF727591 or IncpKPHS1 group. Results: p205880-qnrS carried a novel transposon Tn6396, which was an ISKpn19-compsite transposon and represented a prototype transposable element carrying a minimum core qnrS1 module. p11219-CTXM harbored a novel transposon Tn6559, which was generated from integration of a truncated IS903D-blaCTX-M-14-ISEcp1 unit into the Tn3-family cryptic unit transposon Tn1722. Two Inc groups, IncFIIpKF727591 and IncpKPHS1, of plasmids from Enterobacteriaceae species were proposed, and IncFIIpKF727591 was further grouped into two subgroups IncFIIpKF727591α and IncFIIpKF727591β. Each of the 11 IncFIIpKF727591 plasmids carried multiple accessory modules including at least one resistance module, and the relatively small IncFIIpKF727591 backbones could acquire a wealth of foreign genetic contents. The modular structures of plasmid backbones were conserved within each of IncFIIpKF727591α and IncFIIpKF727591β subgroups but dramatically different, although with similar gene organizations, between these two subgroups. The IncpKPHS1 backbones were conserved with respect to modular structures, and only four of the 14 IncpKPHS1 plasmids carried accessory modules, two of which contained resistance genes. Conclusion: A genomic comparison of sequenced IncpKPHS1 or IncFIIpKF727591 plasmids provides insights into modular differences and genetic diversification of these plasmids, some of which carries antimicrobial resistance genes.