IncC bla-positive plasmid characterised from ST648 Escherichia coli.

OBJECTIVES

This study describes the characterisation of type 2 IncC plasmids pC-Ec20-KPC and pC-Ec2-KPC, carrying thebla gene, from two multiresistant Escherichia coli recovered in University Hospital of Larissa (Greece) in 2018.

METHODS

E. coli strains Ec-2Lar and Ec-20Lar were recovered from rectal swabs of two patients during monthly surveillance cultures. Transfer experiments by conjugation were carried out using rifampicin-resistant E. coli A15 laboratory strain as recipient. bla-carrying plasmids were characterised by S1 profiling. Isolates were typed by MLST. Whole-genome sequencing was performed using the Sequel platform.

RESULTS

Both E. coli isolates, belonging to ST648, transferred bla to E. coli A15 by conjugation. Plasmid analysis revealed that the transconjugants harboured bla-positive plasmids of different sizes. Analysis of plasmid sequences showed that in both isolates the bla gene was carried on a type 2 IncC plasmid (pC-Ec20-KPC and pC-Ec2-KPC, respectively). Both plasmids carried the ARI-B resistance island consisting of several resistance genes, intact and truncated copies of several mobile elements, and a 25 571-bp segment harbouring coding sequences for an iron transporter. The bla gene was part of transposon Tn4401a, which was bounded by 5-bp direct repeats (TCCTT) suggesting its transposition into the IncC plasmids.

CONCLUSION

To our knowledge, this is the first report on complete nucleotide sequences of type 2 IncC plasmids. These findings, which hypothesise the acquisition of KPC-2-encoding transposon Tn4401a by an IncC replicon, indicate the ongoing need for molecular surveillance studies of multidrug-resistant pathogens. In addition, they underline the increasing clinical importance of the IncC plasmid family.