Transfer of carbapenem-resistant plasmid from Klebsiella pneumoniae ST258 to Escherichia coli in patient

Abstract

Klebsiella pneumoniae carbapenemase (KPC) 3-producing Escherichia coli was isolated from a carrier of KPC-3-producing K. pneumoniae. The KPC-3 plasmid was identical in isolates of both species. The patient's gut flora contained a carbapenem-susceptible E. coli strain isogenic with the KPC-3-producing isolate, which suggests horizontal interspecies plasmid transfer.

Figure 1

A) Analysis of Klebsiella pneumoniae carbapenemase (KPC)–encoding plasmids in isolates Kpn1 (1), Eco2 (3), Kpn1-T (2), and Eco2-T (4), Israel, 2008. Plasmid size estimation was performed by digestion of DNA with S1 nuclease (20 U; Promega, Madison, WI, USA) followed by pulsed-field gel electrophoresis (PFGE) with the CHEF-DR III apparatus (Bio-Rad Laboratories, Inc., Hercules, CA, USA), as described (–11). Lambda ladder PFG marker (New England Biolabs, Beverly, MA, USA) was used as a molecular size marker (lane M). B) Restriction fragment length polymorphism of the KPC-3–encoding plasmid from Kpn1-T (K) and Eco2-T (E). Plasmid DNA was digested with BamHI, BglII, EcoRI, and SacI endonucleases (New England Biolabs) and underwent PFGE on a 1% agarose gel. The level of similarity between restriction patterns was calculated by using GelcomparII software version 5 (Applied Maths, Kortrigk, Belgium). Lane 1, 1-kb DNA ladder (New England Biolabs). C) Southern blot analysis of plasmid DNA hybridized with bla_KPC-3-labeled probe. Plasmid restriction products were transferred to a Hybond N⁺ membrane (Amersham Biosciences, Little Chalfont, United Kingdom), cross-linked with UV light, and hybridized with a bla_KPC-3-labeled probe (892-bp product of bla_KPC-3).

Figure 2

Pulsed-field gel electrophoresis demonstrating genetic relatedness of study isolates Eco2, Eco1, and Kpn1, and a representative Klebsiella pneumoniae isolate of the epidemic clone, Kpn ST258, Israel, 2008. Bacterial DNA was prepared and cleaved with 20U SpeI endonuclease (New England Biolabs, Beverly, MA, USA), followed by electrophoresis in a CHEF-DR III apparatus (Bio-Rad Laboratories, Inc., Hercules, CA, USA), as described (4). The macrorestriction patterns of the isolates were compared according to the Dice similarity index (1.5% tolerance interval) by using GelcomparII software (Applied Maths, Kortrigk, Belgium).