Assessment of antimicrobial potential of cell-free supernatant from Lacticaseibacillus paracasei SRG isolated from the vaginal microbiota of healthy women against uropathogens

Abstract

Among women, urinary tract infection (UTI) represents a major health concern. Approximately 50% of the adult female population experienced an episode of UTI at least once. UTI and recurrent UTIs caused by resistant bacteria are very common in clinical settings. The treatment and management of UTI is becoming more challenging because of the rise in antibiotic-resistant bacteria. Lactobacillus spp are the dominant bacterial genus in urinary and vaginal microbiota, which are also used as probiotics. In this study, Lacticaseibacillus paracasei SRG isolated from the vagina of healthy women were evaluated for its probiotic-associated properties and cell-free supernatant (CFS)-mediated antibacterial activity against eight uropathogens. The antibacterial activity of CFS was concentration- and pH-dependent, which was significantly evident at CFS/2 and CFS/4 concentrations and acidic pH values of 4 and 5. The antibacterial activity in CFS remains unaltered even after heat and proteinase K treatment, which suggests the role of heat- and protease-resistant metabolites beside the contributions from acidic conditions. L. paracasei SRG showed strong autoaggregation (85.32%) and cell-surface hydrophobicity (55.60%). In addition, it also exhibits co-aggregation with all indicator strains, suggesting substantial interaction with diverse pathogenic bacteria. These observations highlighted the L. paracasei SRG as a potential probiotic candidate developed from indigenous vaginal microbiota.