Isolation and Identification of Effective Probiotics on Staphylococcusepidermidis Strains Isolated from Urine Sample

Background: The rise of antibiotic-resistant strains of Staphylococcus epidermidis (S.epidermidis) underscores the urgent need for alternative therapeutic strategies. Probiotics, withtheir ability to competitively exclude pathogens and modulate the host immune response, presentpromising candidates for combatting S. epidermidis infections. This study investigated theeffectiveness of probiotics on S. epidermidis growth inhibition.Methods: We isolated S. epidermidis from urine samples of hospitalized patients in Isfahan,Iran, and probiotic strains from yogurt and milk. The antibacterial activity of probiotics againstS. epidermidis was assessed through agar well diffusion and broth microdilution tests. Time-killtests and acid tolerance assessments were performed. Anti-biofilm effects were evaluated, andpotential inhibitory mechanisms were explored. Chemical analysis was done using high-performance liquid chromatography (HPLC), and cytotoxicity was assessed by performing MTT.Results: Streptococcus lutetiensis OR۴۹۶۹۲۷.۱ (S. lutetiensis) and Lactobacillus plantarumOR۴۹۶۹۲۸ (L. plantarum) probiotics were isolated from dairy. S. lutetiensis and L. plantarumstrains had a cytotoxicity effect on S. epidermidis isolates at ۱/۲ and ۱/۴ minimum inhibitory۲concentration (MIC), respectively. L. plantarum grew at pH ۳, while S. lutetiensis displayedgrowth at pH ۳ and ۴. Both probiotic strains demonstrated anti-biofilm activity, with L.plantarum generally exhibiting more potent effects. Lactic acid, formic acid, and acetic acidwere identified as the predominant organic acids produced by the probiotic strains, whichattributed to their inhibitory effects. Toxicity was observed at a concentration of ۵۰% after ۲۴hours, while cell viability remained unaffected at lower concentrations.Conclusion: The findings underscore the promise of probiotics in combating antibiotic-resistantS. epidermidis infections, emphasizing the importance of further research to explore theirtherapeutic potential and optimize treatment strategies.

Keywords:

Lactobacillus plantarum , Staphylococcus epidermidis , Probiotic , Streptococcuslutetiensis