Assessing the efficacy of postbiotics derived from Lactobacillus plantarum on antibiotic resistance genes in nosocomial pathogens such as Enterococcus faecalis and Pseudomonas aeruginosa

This study investigated the antibacterial and anti-biofilm properties of postbiotics derived from Lactobacillus plantarum and their effect on the expression of antibiotic resistance genes (ermB and blaKPC) in Enterococcus faecalis and Pseudomonas aeruginosa, respectively. Cell-free supernatants (CFSs) were analyzed through gas chromatography-mass spectrometry (GC-MS), which showed that butyric acid (14.31%) was the major compound, other metabolites present in CFSs included lactic acid (5.94%), hdroxyacetone (5,21%), benzoic acid (3.12%), Pyrrolo[1,2-a] pyrazine-1,4-dione (1.91%), 2,3-Butanediol (1.04%), and 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one (0.73.%). To investigate the effect of postbiotics on bacterial growth and biofilm formation, minimal inhibitory concentration (MIC) and microtiter plate assays were used. MIC results showed that resistant E. faecalis and P. aeruginosa can grow at concentrations of 2.5 mg/ml and 5 mg/ml, respectively, after exposure to postbiotics. Furthermore, the microtiter plate results showed that postbiotics significantly reduced biofilm formation: 51%, 45% and 39% in E. faecalis and 46%, 38% and 27% in P. aeruginosa at different concentrations.Real-time PCR also confirmed the reduction of resistance genes (ermB; P = 0.007, and blaKPC; P = 0.02) expression. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay showed that the cell survival rate was 80%. These findings suggest that postbiotics from L. plantarum may be a promising approach for combating bacterial growth, biofilm formation, and antibiotic resistance.