Reversion to susceptibility of a carbapenem-resistant clinical isolate of klebsiella pneumoniae producing KPC-3

Objectives:We report the case of a kidney-transplant patient, suffering an intra-abdominal abscess at the surgical site caused by a carbapenem-resistant ST258 Klebsiella pneumoniae clone, producing the KPC-3 carbapenemase. Under tigecycline treatment, the patient developed a sepsis caused by a carbapenem-susceptible ST258 K. pneumoniae strain. Complete DNA sequences of the plasmids carried by the resistant and susceptible strains from this patient were determined. Methods: The complete DNA sequences of plasmids were obtained by applying the 454 Genome Sequencer FLXPLUSprocedure onalibrary constructed of total plasmidDNApurified fromthe carbapenem-resistantand-susceptible strains. Results: In the carbapenem-resistant strain, four plasmids encoding 24 resistance genes, including blaKPC-3, and two putative virulence clusters were detected. In the susceptible strain, large rearrangements occurred in the KPC-carrying plasmid, causing the deletion of the entire Tn4401::bla_KPC-3 transposon, with the consequent reversion of the strain to carbapenem susceptibility. The patient was successfully treated with carbapenems and fully recovered. Conclusions: The description of the plasmid content in these two strains gives interesting insights into the plasticity of KPC-carrying plasmids in K. pneumoniae.