FIG 3.

Host range and transfer of NDM resistance. (A) In vitro mating of NDM donors to clinical isolates of K. pneumoniae, E. cloacae, and S. marcescens or the azide-resistant E. coli strain J53, under aerobic (solid bar) or anaerobic (striped bar) conditions. For highly drug-resistant ECO-222 and ECO-165, E. coli J53 NDM transconjugants were used as donors. Asterisk indicates transfer of the pNRM-190 plasmid to the J53 recipient that showed a log difference of more effective mating under aerobic conditions. All other matings showed no significant differences between aerobic and anaerobic conditions. (B) Table illustrating modes of NDM transmission to recipients. (C) Proposed mechanism for the movement of an IS26-bounded composite transposon from the pNDM-222 donor plasmid in strain ECO-222 to an IncF1A plasmid in the recipient E. cloacae. Boxed region shows the IS26-bounded sequences. 1 and 2, IS26 appears to have mobilized out of the donor plasmid (1) and integrated into the recipient plasmid via homologous recombination of the identical IS91 family insertion sequences (2).