Investigating microbiota and biochemical changes in vaginal fluid toward point-of-care microbial monitoring using surface-enhanced Raman spectroscopy.

SIGNIFICANCE: Vaginal health is maintained by the vaginal microbiome, and dysbiosis of this community can have lifelong negative consequences for women. Current clinical techniques for detecting bacteria in the vagina rely on subjective visual and microscopic analysis or untimely microbial culturing. Surface-enhanced Raman spectroscopy (SERS), a biochemical fingerprinting technique, shows potential for filling this gap as it can identify bacterial species and strains.

AIM: In this study, SERS was used to investigate biochemical changes in vaginal fluid when common vaginal bacteria were present and absent. Subsequently, the performance of a portable Raman spectrometer to detect these biochemical changes was evaluated.

APPROACH: Vaginal fluid was collected from participants attending routine gynecology exams, and SERS spectra were collected using a Raman microscope and a portable spectrometer. Partial least squares, peak intensity, and peak ratio analysis were used to investigate biochemical differences. Quantitative polymerase chain reaction was performed for characterization of Lactobacillus iners, Lactobacillus crispatus, Gardnerella vaginalis, and Streptococcus agalactiae content.

RESULTS: Gardnerella vaginalis presence was characterized by a significant increase in protein and lipid-related features and a decrease in organic acid peaks. The presence of Lactobacillus iners was represented by increased organic acid peaks and a reduction of protein, amino acid, and polysaccharide-related features. Similar trends with little loss of significance were observed when comparing the performance of a Raman microscope and a portable spectrometer.

CONCLUSION: We highlight the feasibility of SERS for detecting differences in bacterial species presence in vaginal fluid and showcase the potential for clinical translation.