Discussion In this paper we describe diverse interactions among pA/C, pX1 and pColE1-like plasmids within a single strain. When strain YU39 was challenged for conjugation different phenomena were recorded, depending on the recipient strain. When bla CMY-2 was

transferred, three genetic interactions occurred at very low frequencies: 1) the co-integration of pA/C and pX1; 2) the transposition of the CMY region from pA/C to pX1; or 3) the rearrangement of pA/C. Moreover, the trans-mobilization of the pColE1-like plasmid occurred in most of the cases. The general outcome of these processes was the transfer of the bla CMY-2 gene from a non-conjugative pA/C to a highly conjugative pX1 plasmid. Both the this website resultant pA/C + pX1 and pX1::CMY plasmids acquired the capacity to spread ESC resistance at very high levels by conjugation (Figure 7). This mode of cis-mobilization and transfer of the bla CMY-2 gene has not been previously reported. Figure 7 Schematic representation of BB-94 cell line the outcome of the conjugative transfer of the YU39 IncA/C plasmid-borne Lazertinib nmr bla CMY-2 gene to different recipient strains. On the left side is the donor strain YU39 harboring pA/C, pX1 and pColE1-like plasmids. In the middle, The first round conjugation frequencies are indicated above the black arrows along with the recipient strains

involved in the different phenomena. The three different types of transconjugants observed for the first round are depicted. The pSTV and pColE1-like plasmids are shown, although they were not present in all the transconjugants. Electroporation step to DH5α for the transconjugants plasmids is represented with the grey arrows. Following are the range of the second round conjugation frequencies in the “original” and DH5α strains (see text for details). The outcome Amine dehydrogenase of conjugation was dependent on the recipient stain Distinct interactions occurred among the pA/C, pX1 and pColE1-like plasmids within the

donor YU39 strain, albeit at very low frequencies. One of the most surprising results was that these interactions were differentially “sampled” in a recipient-dependent manner. We would expect to find differences between Typhimurium and E. coli due to the induced mutations carried by the E. coli laboratory strains (such as recA-). However, in general terms E. coli and Typhimurium strains shared similar results: DH5α and SO1 received and harbored pA/C and pColE1-like, while LT2 and HB101 received and harbored pX1. The study of the genetic interactions among pA/C, pX1 and pColE1-like was beyond the scope of this study. The interactions between relaxases and the pX1 coupling protein will be addressed in future studies. Moreover, the complete sequencing of the YU39 genome and representative plasmid re-arrangements is underway. Co-integration of the non-conjugative pA/C with the highly conjugative pX1 IncA/C plasmids encoding multi-drug resistance have been extensively studied and are known for their diversity and plasticity [6, 19, 20].