Vaginal microbiota (VMB) is composed of billions of microbes, with the most abundant representatives belonging to the Lactobacillus genus. Reduction in the number of lactobacilli can lead to dysbiosis, potentially resulting in bacterial vaginosis (BV) or vulvovaginal candidiasis (VVC). These conditions predominantly affect women of reproductive age, causing uncomfortable symptoms and, in some cases, pose greater health risks. Conventional therapies for BV and VVC involve antibiotics or antifungals. Both conditions exhibit a high rate of recurring episodes, which decreases the quality of life of the affected individuals. To avoid chronic use of antibiotics and antifungals, the use of probiotics for local administration for treatment of BV and VVC is being researched. As part of our master's thesis, our aim was to review scientific literature on the local use of lactobacilli for the treatment or prevention of vaginal infections. Additionally, we conducted laboratory isolation and identification of lactobacilli from vaginal swabs.
We conducted a literature review of vaginal lactobacilli in three sections: a) isolation and characterization, b) formulation studies, and c) in vivo studies. Searches were performed in three different databases. The review only included clinical studies or scientific articles in English, published by November 2022. In the laboratory, vaginal swabs were inoculated onto blood agar and the individual species were purified. The isolated lactobacilli were identified using MALDI-TOF MS.
A total of 1265 articles were obtained, of which only 88 publications were deemed relevant. 40 articles addressed the isolation and characterization of lactobacilli, 6 were formulation studies, and 42 included in vivo testing. In the laboratory, we isolated L. crispatus (31%), L. jensenii (30%), L. gasseri (17%), L. iners (11%), L. vaginalis (7%), L. rhamnosus (1%), L. coleohominis (1%), L. fermentum (1%), and L. plantarum (1%) from vaginal swabs of 127 healthy volunteers.
Lactobacilli isolation methods have remained unchanged over time, while there has been a significant shift towards genotypic and spectroscopic methods in identification. The development of new delivery systems for local application of probiotics is mainly directed towards nanofibers. L. rhamnosus has been the most extensively studied probiotic for treating BV and VVC in clinical trials. We observed strain-specific colony morphologies. The VMB of volunteers matched literature data on the composition of healthy VMB in Caucasian women.
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