Rapid antimicrobial susceptibility profiling using impedance spectroscopy.

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Microbiology

Background:

• Current antibiotic susceptibility testing (AST) methods are often time-consuming, labor-intensive, or costly.
• Impedance spectroscopy offers a rapid, label-free, real-time, and affordable approach for bacterial analysis.
• Existing impedance spectroscopy techniques for AST face limitations due to complex chip designs and cell enrichment requirements.

Purpose of the Study:

• To develop a simplified, label-free impedance spectroscopy method for rapid antibiotic susceptibility testing (AST).
• To enhance impedance sensitivity using a low conductivity zwitterionic buffer in simple interdigitated electrodes (IDEs).
• To enable AST in under 20 minutes without liquid flow, biofunctionalization, or cell enrichment.

Main Methods:

• Utilized a label-free impedance spectroscopy technique with simple interdigitated electrodes (IDEs).
• Employed a low conductivity zwitterionic buffer to amplify impedance signal sensitivity.
• Measured changes in solution resistance correlating to antibiotic-induced bacterial cell death or growth.

Main Results:

• Achieved rapid AST in as little as 20 minutes.
• Demonstrated a cell death-based approach for bactericidal antibiotics (20 min) and a cell growth-based approach for broader drug types (60-80 min).
• Successfully determined antibiotic sensitivity and minimum inhibitory concentrations (MICs) for common bacteria (E. coli, K. pneumoniae, S. aureus) against various antibiotic classes.

Conclusions:

• The developed method provides a fast, sensitive, and versatile platform for clinical AST.
• This simplified impedance spectroscopy approach overcomes previous limitations, paving the way for broader clinical adoption.
• The technique accurately assesses bacterial response to diverse antibiotics, aiding in timely treatment decisions.