Friederike is back from EMBO Workshop 12-16 June 2022 Ascona, Switzerland

Abstract

Microfluidic hollow fiber model to visualize and quantify bacterial response to dynamic drug treatments

Friederike-Leonie Born and Petra S. Dittrich

Heterogeneity of bacterial populations is considered an important factor in developing antibiotic resistance and persistence. In vitro static assays, routinely used in clinics to identify potential resistance, do not sufficiently address the intercellular heterogeneity. Moreover, mimicking in vivo conditions, where bacterial cells are temporarily exposed to different antibiotic concentrations is only possible with dynamic models. The available dynamic in vitro models, e.g., the Hollow Fiber Infection Model (HFIM), require vast amounts of drugs and cells per experiment. Further, the drug effects are evaluated after the invasive sampling and only represent a finite moment in time. Inspired by the HFIM, we developed a dynamic, microfluidic in vitro model to investigate the antibiotic treatment effects over time, with single-cell resolution, requiring only a fraction of volumes necessary for HFIM. The bacterial cells are confined in fibrin hydrogel, gradually exposed to antibiotic drugs with a pump ratio-based gradient generator and monitored using time-lapse microscopy for up to 15 hours. The developed model is characterized using Escherichia coli ATCC 25922, exposed to single drugs and combinations (Doxycycline, Amoxicillin). Preliminary results generated using different concentrations of Amoxicillin indicate that cells gradually exposed to an antibiotic drug show a reduced mortality rate but greater morphological changes than cells constantly exposed to the same drug. In the future, we will further focus on comparing constant versus gradient shaped dosing and we will extend our study to clinically relevant pathogen.