Sedimentation Field-Flow Fractionation: A Diagnostic Tool for Rapid Antimicrobial Susceptibility Testing

Area of Science:

• Microbiology
• Analytical Chemistry
• Biotechnology

Background:

• Conventional antimicrobial susceptibility testing (AST) methods are time-consuming (24-48 hours).
• This delay necessitates probabilistic antibiotic therapy, increasing the risk of antibiotic resistance.
• Rapid AST methods are crucial for timely and effective treatment.

Purpose of the Study:

• To investigate sedimentation field-flow fractionation (SdFFF) as a rapid method for bacterial antibiotic susceptibility testing.
• To assess SdFFF's ability to detect antibiotic-induced morphological changes in bacteria.
• To establish a quantitative measure for differentiating susceptible and resistant bacterial strains.

Main Methods:

• Utilized SdFFF in "Hyperlayer" elution mode for bacterial analysis.
• Tested three bacterial species: *Escherichia coli*, *Klebsiella pneumoniae*, and *Pseudomonas aeruginosa*.
• Quantified antibiotic effects using the percentage variation of the retention factor (PΔR) and established a 16.8% threshold.

Main Results:

• SdFFF successfully monitored antibiotic-induced morphological changes in bacteria.
• A threshold of 16.8% PΔR effectively differentiated susceptible and resistant strains.
• SdFFF achieved 100% categorical agreement with the conventional AST reference method.
• Results were obtained within 3-4 hours, significantly faster than conventional methods (16-24 hours).

Conclusions:

• SdFFF shows significant potential as a rapid AST method.
• The technique enables faster determination of antibiotic susceptibility or resistance.
• Earlier targeted antibiotic therapy can be facilitated by this rapid method.
• Further validation is required for clinical application.