Investigating the antibacterial effects of Lactobacillus plantarum and Streptococcus lutetiensis probiotics strains on coagulase negative strains isolated from urine samples
Investigating the antibacterial effects of Lactobacillus plantarum and Streptococcus lutetiensis probiotics strains on coagulase negative strains isolated from urine samples
Ghazaleh Amini,1,*Hassan Pourmoshtagh,2
1. Department of Microbiology, Falavarjan Branch, Islamic Azad University, Isfahan, Iran 2. Department of Pediatrics, Loghman-Hakim Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran
Introduction: Background: The rise of antibiotic-resistant strains of Staphylococcus epidermidis (S. epidermidis) underscores the urgent need for alternative therapeutic strategies. Probiotics, with their ability to competitively exclude pathogens and modulate the host immune response, present promising candidates for combatting S. epidermidis infections. This study investigated the effectiveness of probiotics on S. epidermidis growth inhibition.
Methods: 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 against S. epidermidis was assessed through agar well diffusion and broth microdilution tests. Time-kill tests and acid tolerance assessments were performed. Anti-biofilm effects were evaluated, and potential inhibitory mechanisms were explored. Chemical analysis was done using high-performance liquid chromatography (HPLC), and cytotoxicity was assessed by performing MTT.
Results: Results: Streptococcus lutetiensis OR496927.1 (S. lutetiensis) and Lactobacillus plantarum OR496928 (L. plantarum) probiotics were isolated from dairy. S. lutetiensis and L. plantarum strains had a cytotoxicity effect on S. epidermidis isolates at 1/2 and 1/4 minimum inhibitory concentration (MIC), respectively. L. plantarum grew at pH 3, while S. lutetiensis displayed growth at pH 3 and 4. Both probiotic strains demonstrated anti-biofilm activity, with L. plantarum generally exhibiting more potent effects. Lactic acid, formic acid, and acetic acid were identified as the predominant organic acids produced by the probiotic strains, which attributed to their inhibitory effects. Toxicity was observed at a concentration of 50% after 24 hours, while cell viability remained unaffected at lower concentrations.
Conclusion: Conclusion: The findings underscore the promise of probiotics in combating antibiotic-resistant S. epidermidis infections, emphasizing the importance of further research to explore their therapeutic potential and optimize treatment strategies.