High-Density E. Coli Cultivation Arrays for Combinatorial Drug Testing With Subsequent Lipid Profiling by MALDI-MS

Area of Science:

• Microbiology
• Drug Discovery
• Analytical Chemistry

Background:

• Bacterial resistance to antibiotics necessitates novel therapeutic strategies.
• Combination therapies show promise for enhanced efficacy and resistance delay.
• Checkerboard assays are standard for assessing drug synergy but lack high-throughput capability.

Purpose of the Study:

• To develop a miniaturized, high-throughput checkerboard assay for combinatorial antibiotic testing against E. coli.
• To validate the platform's performance and assess antibiotic combination effects.
• To investigate lipidomic changes in E. coli under antibiotic stress.

Main Methods:

• Miniaturized checkerboard assay with high droplet density (20832/slide).
• Determination of minimum inhibitory concentrations (MIC) for various antibiotics.
• Assessment of antibiotic synergy using fractional inhibitory concentration indices (FICI).
• Lipidomic profiling using MALDI-MS.

Main Results:

• The platform achieved high sample density and rapid array generation (<25 min).
• Synergistic effect of amoxicillin/clavulanate was replicated.
• Tested combinations showed FICI values indicating indifferent to antagonistic effects.
• Lipidomic analysis identified potential stress-induced changes in phosphatidylethanolamine (PE32:0).

Conclusions:

• The miniaturized assay is a powerful tool for high-throughput combinatorial antibiotic screening.
• The platform facilitates rapid assessment of drug interactions and resistance mechanisms.
• Lipidomic insights may reveal novel biomarkers for antibiotic stress response.