H14 - Comprehensive Raman Spectroscopy Database for Antibiotics to Enable Rapid Structural Comparison and Quality Screening Across Drug Variants

Introduction: : The growing concern over the quality and efficacy of antibiotics from different manufacturing
regions prompted our investigation into their chemical composition and potency. Antibiotics such
as fosfomycin, azithromycin, colistin, levofloxacin, and ciprofloxacin are crucial in treating
infections; however, differences in manufacturing standards between countries could
compromise treatment outcomes. Our project aimed to establish a comprehensive Raman
spectroscopy database for detecting and comparing structural differences in antibiotics sourced
from the United States and China.

Materials and

Methods: : We prepared antibiotic samples by grinding the solid forms and, for light-sensitive samples,
dissolving them in PBS. Raman spectroscopy was performed using a 532 nm laser, and the
spectra were split into cell-silent and CH vibrational regions for targeted analysis. Data
processing included baseline correction, background subtraction, and normalization using
Python algorithms. Minimum inhibitory concentrations (MICs) against E. coli MG1655 were also
measured to validate the spectral findings and link compositional differences to efficacy.

Results, Conclusions, and Discussions::

Results: Raman spectra revealed clear differences between U.S. and Chinese antibiotic samples. For
instance, Azithromycin from China lacked CH vibrational peaks, while Ciprofloxacin showed
drastic intensity losses compared to domestic references. MIC assays supported these findings,
with some international samples requiring 32-fold higher concentrations for bacterial inhibition,
consistent with the observed spectral discrepancies. Overall, compositional differences
correlated with reduced antibiotic potency.

Conclusion: This project successfully demonstrated that Raman spectroscopy can identify subtle yet critical
differences in antibiotic composition. Spectral anomalies consistently predicted variations in
biological potency, establishing Raman spectroscopy as a reliable tool for drug quality
assurance.

Discussion: Our work confirms the feasibility of using Raman-based methods for rapid, non-destructive
screening of antibiotic quality. By combining spectral and biological data, our approach
enhances transparency in pharmaceutical quality control. Future expansions could incorporate
antibiotics from additional regions and explore applications beyond antibiotics, offering a
comprehensive platform for global drug quality monitoring.

Acknowledgements and/or References (Optional)::