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 (8–11). 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).