AUTHOR=Morselli Sara , Ceccarani Camilla , Djusse Marielle Ezekielle , Laghi Luca , Camboni Tania , Consolandi Clarissa , Foschi Claudio , Severgnini Marco , Marangoni Antonella 

TITLE=Anti-chlamydial activity of vaginal fluids: new evidence from an in vitro model

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=14

YEAR=2024

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2024.1403782

DOI=10.3389/fcimb.2024.1403782

ISSN=2235-2988

ABSTRACT=<sec><title>Introduction</title><p>We assessed the <italic>in vitro</italic> anti-chlamydial activity of fresh vaginal secretions, deciphering the microbial and metabolic components able to counteract <italic>Chlamydia trachomatis</italic> viability.</p></sec><sec><title>Methods</title><p>Forty vaginal samples were collected from a group of reproductive-aged women and their anti-chlamydial activity was evaluated by inhibition experiments. Each sample underwent 16S rRNA metabarcoding sequencing to determine the bacterial composition, as well as <sup>1</sup>H-NMR spectroscopy to detect and quantify the presence of vaginal metabolites.</p></sec><sec><title>Results</title><p>Samples characterized by a high anti-chlamydial activity were enriched in <italic>Lactobacillus</italic>, especially <italic>Lactobacillus crispatus</italic> and <italic>Lactobacillus iners</italic>, while not-active samples exhibited a significant reduction of lactobacilli, along with higher relative abundances of <italic>Streptococcus</italic> and <italic>Olegusella</italic>. <italic>Lactobacillus gasseri </italic>showed an opposite behavior compared to <italic>L. crispatus</italic>, being more prevalent in not-active vaginal samples. Higher concentrations of several amino acids (i.e., isoleucine, leucine, and aspartate; positively correlated to the abundance of <italic>L. crispatus</italic> and <italic>L. jensenii</italic>) lactate, and 4-aminobutyrate were the most significant metabolic fingerprints of highly active samples. Acetate and formate concentrations, on the other hand, were related to the abundances of a group of anaerobic opportunistic bacteria (including <italic>Prevotella, Dialister, Olegusella, Peptostreptococcus, Peptoniphilus, Finegoldia</italic> and <italic>Anaerococcus</italic>). Finally, glucose, correlated to <italic>Streptococcus, Lachnospira</italic> and <italic>Alloscardovia</italic> genera, emerged as a key molecule of the vaginal environment: indeed, the anti-chlamydial effect of vaginal fluids decreased as glucose concentrations increased.</p></sec><sec><title>Discussion</title><p>These findings could pave the way for novel strategies in the prevention and treatment of chlamydial urogenital infections, such as lactobacilli probiotic formulations or lactobacilli-derived postbiotics.</p></sec>