Probiotic Potential of Vaginal Lactobacilli Isolates from Healthy Women in Peru Against Clinically Relevant Urogenital Pathogens

Vaginal dysbiosis is associated with an increased risk of urogenital infections and reproductive complications, driving the search for biotherapeutic alternatives based on autochthonous bacteria. The objective of this study was to isolate, identify, and characterize in vitro Lactobacillus strains with probiotic potential from the vaginal microbiota of healthy women in Arequipa, Peru. Methods: A total of 100 healthy women between 18 and 64 years old performed vaginal self-sampling using eSwab® (Copan Italia S.p.A.). Isolates were cultured on MRS agar and identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and complemented with 16S rRNA gene sequencing when identification was not achieved by mass spectrometry. Lactobacillus strains were subjected to preliminary phenotypic safety evaluations (hemolysin, catalase, and gelatinase activities, along with antimicrobial susceptibility via disk diffusion) and functional assessments (in vitro: lactic acid production, acidifying capacity, and inhibitory activity against Gardnerella vaginalis, Candida albicans, Escherichia coli, and Streptococcus agalactiae). Results: A total of 231 bacterial isolates were obtained, 142 of which corresponded to Lactobacillus, with Lactobacillus crispatus as the predominant species (113 strains). Based on preliminary phenotypic safety screening, strains were selected for functional characterization. The strains L. jensenii LMH-0038/LMH-0039 and L. crispatus LMH-0070 demonstrated acidifying capacity and inhibitory activity against G. vaginalis and C. albicans. Widespread ciprofloxacin resistance was detected across the evaluated species. Conclusions: Autochthonous Lactobacillus strains with acceptable preliminary safety profiles and notable in vitro bioactivity against key urogenital pathogens were isolated and identified. In particular, L. jensenii and L. crispatus emerge as promising probiotic candidates.