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Vaginal malodour is a sign of dysbiosis. The biogenic amines (BAs) cadaverine, putrescine and tyramine are known to be causative compounds. Recent reports suggest these compounds produced by pathogens might have a role beyond causing malodour; namely inhibiting the growth of lactobacilli bacteria that are crucial in the maintenance of vaginal homeostasis. The aim of this study was to identify whether certain lactobacilli strains could reduce BAs and to evaluate how Lactobacillus species were affected by these compounds. Using LC–MS and HPLC-UV, five Lactobacillus crispatus strains were identified as being capable of significantly reducing BAs from the media under in vitro conditions. Through 16S rRNA gene sequencing of vaginal swabs exposed to Bas, cadaverine was found to reduce the relative abundance of lactobacilli. When L. crispatus was exposed to media supplemented with BAs with an HCl adjusted lower pH, its growth was enhanced, demonstrating the relevance of the maintenance of an acidic vaginal environment. If strains are to be developed for probiotic application to alleviate bacterial vaginosis and other conditions affecting large numbers of women worldwide, their ability to adapt to Bas and regulate pH should be part of the experimentation.

Vaginal care products are widely used by women to relieve discomfort such as pain, itching and malodour, all of which are commonly caused by conditions resulting from microbiota dysbiosis. Previous studies showed that probiotic strains Lacticaseibacillus (formerly Lactobacillus) rhamnosus GR-1 (LGR-1) and Limosilactobacillus (formerly Lactobacillus) reuteri RC-14 (LRC-14), can aid in restoring homeostasis in the vaginal microbiome when taken orally. A topical product containing these strains could be of value for reducing malodour and improving quality of life. However, the formulation of such a product is a challenge, given that its ingredients must maintain shelf-life viability by excluding moisture. Here, we tested petroleum jelly, mineral oil, coconut oil, and olive oil for how well they maintained the viability of freeze-dried probiotic strains over a six-month timeframe. None of the oils caused excessive loss of bacterial viability, with petroleum jelly and coconut oil showing the most promise. Based on existing knowledge of these oils on the female genitalia, coconut oil and petroleum jelly could be suitable probiotic carriers for clinical testing.