Culture-free Antibiotic-susceptibility Determination From Single-bacterium Raman Spectra

Area of Science:

• Microbiology
• Spectroscopy
• Biotechnology

Background:

• Traditional microbiological diagnostics rely on lengthy bacterial growth phases.
• Rapid antibiotic susceptibility testing is crucial for effective patient treatment and antimicrobial stewardship.
• Raman spectrometry offers label-free, phenotype-related information from single cells.

Purpose of the Study:

• To demonstrate the feasibility of rapid antibiotic susceptibility determination using single-cell Raman spectroscopy.
• To develop a method for analyzing clinical specimens without extensive culturing.
• To establish a rapid diagnostic approach for bacterial infections.

Main Methods:

• Single bacterial cells (E. coli strains) were precultured for two hours.
• Bacteria were incubated for two hours with various bactericidal antibiotics at different concentrations.
• Raman spectra were acquired from single cells and processed to identify antibiotic effects.
• An algorithm was developed to analyze spectral data and overcome cellular heterogeneity.

Main Results:

• An "antibiotic effect signature" characterized by specific Raman peaks was identified.
• Three distinct spectral populations were observed in bacteria exposed to antibiotics.
• The method successfully estimated the Minimum Inhibitory Concentration (MIC) and determined susceptibility phenotypes.
• Accurate susceptibility results were obtained within a four-hour timeframe, including preculture.

Conclusions:

• Single-cell Raman spectroscopy enables rapid antibiotic susceptibility testing in microbiology.
• This technique provides a promising alternative to conventional diagnostic methods, significantly reducing analysis time.
• The developed algorithm effectively handles single-cell variations for reliable phenotypic determination.