Presentation of the doctoral thesis subject: Influence of mobile genetic elements on the dissemination of important resistance determinants in commensale Escherichia coli

Introduction: Antibiotics are important drugs for treating bacterial infections. Nevertheless, bacteria can be resistant against certain types of antibiotics. Here, resistance plasmids have an important role. To prevent development of resistance against antibiotics different plans of action where designed. The ARDIG project, located in the One-Health – European Joint Programme is a result of this approach. The aim of the doctoral thesis, located in this ARDIG project, is the investigation of Antibiotic Resistance Dynamics and the detailed characterization of antimicrobial resistances. A focus will be set on substances in the group of (fluoro)quinolone and the last resort antibiotic Colistin.

Material and Methods: To answer questions regarding the Antibiotic Resistance Dynamics, different Escherichia coli isolates recovered from livestock and food will be analyzed in detail. These isolates were provided by the National Reference Laboratory for Antimicrobial Resistance that is hosted by the BfR. At first, isolates will be characterized for their phenotypic resistance profile especially for fluorquinolones and colistin. Further, classification into different resistance variation is aimed. Diverse conventional PCR and real-time PCR methods as well as PFGE-analyzes will be conducted. For genome dissection, the application of short- and long-read sequencing is planned. This will help to understand the genetic basis of the resistance profile more deeply. Thereby, the focus is set on plasmids providing antimicrobial resistances. In addition, in vivo analysis regarding the transmission and stability of resistance plasmids are intended. This should be helpful when trying to determine factors benefitting or inhibiting spread of resistance plasmids.

Results and Conclusion: The aim during the dissertation is to gain detailed understanding of the genetic diversity and transmission of colistin- and quinolone-resistances. Experiments on antibiotic resistance dynamics will enable us to determine relevant factors preserving certain resistances or relevant factors to support the loss of resistance plasmids. This knowledge can be of great importance for targeted action against the spread of resistance.