Antibiotic susceptibility test under a linear concentration gradient using travelling surface acoustic waves

Area of Science:

• Biomedical Engineering
• Microfluidics
• Microbiology

Background:

• Accurate antibiotic susceptibility testing (AST) is crucial for combating antimicrobial resistance.
• Traditional AST methods can be time-consuming and require serial dilutions.
• Microfluidic devices offer potential for rapid and efficient diagnostics.

Purpose of the Study:

• To develop a microfluidic device for rapid formation of linear antibiotic gradients.
• To utilize travelling surface acoustic waves (TSAWs) for controlled mixing and gradient generation.
• To demonstrate the device's efficacy in antibiotic susceptibility testing for pathogenic bacteria.

Main Methods:

• Fabrication of a microfluidic chip on a lithium niobate (LiNbO3) substrate.
• Generation of TSAWs using a focused interdigital transducer to induce acoustic streaming.
• Creation of linear antibiotic concentration gradients within the microfluidic channel.
• Exposure of bacteria (Pseudomonas aeruginosa, Escherichia coli) to the gradient and determination of minimal inhibitory concentration (MIC).

Main Results:

• The device successfully generated linear antibiotic concentration gradients in seconds.
• The generated gradients enhanced the reliability of MIC measurements.
• Efficient determination of appropriate antibiotic doses for Pseudomonas aeruginosa and Escherichia coli was achieved.
• The method proved effective for both slowly and rapidly proliferating bacteria.

Conclusions:

• TSAW-induced acoustic streaming provides a rapid and controlled method for generating antibiotic gradients in microfluidics.
• This technology enables efficient and accurate antibiotic susceptibility testing.
• The developed device has significant potential for improving antimicrobial resistance diagnostics and guiding treatment decisions.