A low-footprint, fluorescence-based bacterial time-kill assay for estimating dose-dependent cell death dynamics

Area of Science:

• Microbiology
• Pharmacology
• Biotechnology

Background:

• Traditional optical density (OD) assays for antibiotic dose-response curves in bacteria obscure cell death dynamics, only reflecting net population changes.
• Existing time-kill assays for quantifying bacterial death rates are resource-intensive and susceptible to bias from residual antibiotic carryover.

Approach:

• Developed a novel, fluorescence-based time-kill assay using resazurin as a viable cell indicator.
• The assay significantly reduces material costs and demonstrates robustness against residual drug carryover.
• Validated the method by quantifying dose-dependent death rates in *Escherichia coli* exposed to cefotaxime.

Key Points:

• The resazurin-based assay accurately quantifies dose-dependent bacterial death rates, unlike OD-based methods.
• The technique is resilient to extracellular debris and cell aggregation, ensuring reliable measurements.
• This method provides a more accurate assessment of bacterial response to antibiotics.

Conclusions:

• The novel fluorescence assay offers a cost-effective and reliable alternative for bacterial time-kill experiments.
• Accurate dose-response curves generated by this method can enhance pharmacokinetic-pharmacodynamic (PK/PD) modeling.
• This advancement has the potential to improve antibiotic therapy strategies and drug development.