ESBL-plasmids carrying toxin-antitoxin systems can be %26quot;cured%26quot; of wild-type Escherichia coli using a heat technique

作者：Schaufler Katharina^*; Wieler Lothar H; Semmler Torsten; Ewers Christa; Guenther Sebastian

来源：Gut Pathogens, 2013, 5(1): 34.

DOI：10.1186/1757-4749-5-34

• Plasmid
• ESBL
• E. coli
• Toxin-antitoxin system
• Plasmid-%26quot
• cured%26quot
• -variant

Background: Plasmid-encoded extended-spectrum beta-lactamase (ESBL)-enzymes are frequently produced by Escherichia coli. Several ESBL-plasmids contain genes for toxin-antitoxin (TA) systems, which assure the maintenance of plasmids in bacteria and prevent the cells from %26quot;post-segregational killing%26quot;. These systems limit options to %26quot;cure%26quot; plasmids of ESBL-wild-type strains due to the death of the bacterial cells. A helpful tool to understand the role of ESBL-plasmids in the dissemination of pandemic multi-resistant E. coli are ESBL-plasmid-%26quot; cured%26quot;-variants (PCVs) and their comparison to ESBL-wild-type strains. The purpose of this study was to construct PCVs of ESBL-wild-type E. coli strains despite the presence of genes for TA systems. %26lt;br%26gt;Findings: Using enhanced temperatures and brain-heart-infusion broth it was possible to construct viable PCVs of wild-type ESBL-E. coli strains. The occurrence of TA system-genes including hok/sok, srnB/C, vagC/D, pemI/K on ESBL-plasmids of replicon types FIA or FIB was demonstrated by bioinformatic analyses. The loss of the plasmid and the genetic identity of PCV and corresponding wild-type strain was confirmed via different methods including plasmid-profile-analysis, pulsed-field gel electrophoresis and bioinformatics using generated whole genome data of the strains. %26lt;br%26gt;Conclusions: This short report describes the successful construction of viable PCVs of ESBL-wild-type E. coli strains. The results are hence surprising due to the fact that all %26quot;cured%26quot; ESBL-plasmids contained at least one complete toxin-antitoxin system, whose loss would normally mean the death of bacterial cells.

• 出版日期2013-11-19