Antibiotic Susceptibility Test with Surface-Enhanced Raman Scattering in a Microfluidic System

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Microfluidics

Background:

• Antibiotic susceptibility testing (AST) is crucial for treating serious bacterial infections but typically requires 2-5 days.
• Current methods using surface-enhanced Raman scattering (SERS) reduce AST time but still necessitate lengthy bacterial culture.
• Manual AST procedures are prone to contamination and human error, impacting diagnostic accuracy and speed.

Purpose of the Study:

• To develop an integrated microfluidic system for rapid, on-chip bacterial enrichment, metabolite collection, and SERS-based AST.
• To overcome limitations of existing AST methods, including long culture times and susceptibility to contamination.
• To enable faster and more reliable antibiotic susceptibility determination for clinical diagnosis.

Main Methods:

• A microfluidic system integrating membrane filtration and SERS-active substrate (MF-SERS) was designed and fabricated.
• The system performs on-chip bacterial enrichment, metabolite filtration, and in situ SERS measurements.
• Escherichia coli was used as a model organism to demonstrate the system's capabilities.

Main Results:

• The MF-SERS system achieved a SERS detection limit of 10³ CFU/mL for E. coli, a 4-log improvement over centrifugation.
• This significantly reduced the required bacterial culture time, accelerating the overall AST process.
• The enclosed microfluidic environment minimized contamination and human error during bacterial trapping, filtration, and SERS detection.

Conclusions:

• The developed MF-SERS system enables integrated bacterial processes for rapid AST.
• The system demonstrates successful AST on E. coli at low concentrations (10³ CFU/mL).
• This microfluidic approach offers a miniature, well-confined solution for faster and more accurate bacterial infection diagnosis.