Enzymatic assay to test diamines produced by vaginal bacteria

An enzymatic assay was developed to determine the concentration of diamines (DA) in clinical samples of vaginal fluids. Putrescine and cadaverine are DA produced by anaerobic bacteria and are typically present in the vaginal fluids of women with an abnormal microbiota, as occurs in bacterial vaginosis. The vaginal DA (VADA) assay is based on the enzyme diamine oxidase which reacts with putrescine and cadaverine to produce H2O2 in a quantitative manner. H2O2 concentration is measured spectrophotometrically by a chromogenic reaction catalyzed by horseradish peroxidase. The VADA assay proved to be capable of detecting DA concentrations as low as 4 mM and showed a dose-response relationship which was linear over DA concentrations ranging from 4 to 256 mM. Using clinical samples it was possible to show that the VADA assay can be performed on human vaginal swabs and that the mean DA concentration is significantly higher in samples positive for microbial pathogens.