A pilot study has demonstrated that surface-enhanced Raman spectroscopy (SERS) can detect key bacterial species in vaginal fluid through distinct biochemical fingerprints – offering a potential new, portable tool for monitoring vaginal microbiome health.
The researchers from Vanderbilt University, USA, used both a laboratory Raman microscope and a portable Raman spectrometer to analyze samples of vaginal fluid collected from 19 participants.
The spectra were acquired using colloidal silver nanoparticle substrates, which enhance Raman scattering to boost detection sensitivity for low-abundance biomolecules. Spectral data were evaluated using principal component analysis (PCA) and intensity ratio analysis to assess biochemical composition, including levels of proteins, lipids, organic acids, and polysaccharides. The results were then compared against microbial profiles obtained using quantitative PCR, focusing on four species: Lactobacillus iners, Lactobacillus crispatus, Gardnerella vaginalis, and Streptococcus agalactiae.
Biochemical trends in the SERS data reflected the presence of specific microbes. Samples containing G. vaginalis – a bacterium associated with bacterial vaginosis – exhibited elevated protein and lipid signals alongside reduced organic acids, consistent with its known disruption of vaginal homeostasis. In contrast, samples positive for L. iners, a commonly overlooked but protective bacterium, showed increased organic acid content and decreased signals from proteins and polysaccharides.
Notably, these spectral patterns were observable with both high-end and portable Raman systems, suggesting potential for point-of-care applications.
The study also found that G. vaginalis signatures appeared in samples from participants without diagnosed infections or symptoms, indicating that SERS could detect early or subclinical microbiome shifts before clinical onset.
“Overall, this study shows the potential of SERS to detect bacterial species in the vaginal microbiome toward increased monitoring of vaginal health,” the authors concluded.
The team plans to expand the participant cohort and integrate next-generation sequencing in future work to broaden microbial coverage and improve diagnostic specificity.
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