Fast Antibiotic Susceptibility Testing via Raman Microspectrometry on Single Bacteria: An MRSA Case Study

Area of Science:

• Microbiology
• Spectroscopy
• Diagnostic Technology

Background:

• Ultrafast antibiotic susceptibility testing remains a challenge in infectious disease diagnostics.
• Raman microspectroscopy has shown promise for phenotypic susceptibility determination.
• Gram-positive cocci like Staphylococcus aureus present unique challenges for this technique.

Purpose of the Study:

• To evaluate the feasibility of single-cell Raman spectroscopy for determining cefoxitin susceptibility in Staphylococcus aureus.
• To assess the impact of cell-to-cell variability and incubation conditions on spectral analysis.
• To confirm and extend previous findings on Raman-based antibiotic susceptibility testing to S. aureus.

Main Methods:

• Utilized an automated single-cell Raman spectrometer and a standardized sample preparation protocol.
• Analyzed 9429 S. aureus single cells from cefoxitin-resistant and susceptible strains.
• Incubated cells with varying concentrations of cefoxitin and analyzed spectral changes.

Main Results:

• Observed weaker spectral effects in S. aureus compared to previous studies.
• Noted higher cell-to-cell response variability and significant impact of incubation conditions.
• Successfully correlated bacterial phenotype with spectral modifications using majority voting.

Conclusions:

• Single-cell Raman spectroscopy is applicable to S. aureus antibiotic susceptibility testing.
• The method requires further development to address limitations and for industrial application.
• This approach advances rapid diagnostics for infectious diseases caused by S. aureus.