Antibiofilm and Antibacterial Activities of Probiotic-Derived Cell-Free Supernatants against Multidrug-Resistant Clinical Isolates of Pseudomonas aeruginosa

Abstract

 Pseudomonas aeruginosa is a significant opportunistic pathogen and the capacity to form biofilms and multidrug resistance restricts the usefulness of traditional antibiotic treatment in the case of HAIs. The extracellular metabolites of probiotics are called cell-free supernatants (CFSs) and may have antibacterial and antibiofilm activity. The antibacterial and antibiofilm properties of CFSs produced by Lactiplantibacillus plantarum, Lacticaseibacillus rhamnosus, and Lactobacillus acidophilus were evaluated against clinical P. aeruginosa isolates, especially multidrug-resistant (MDR) and biofilm-producing ones. All 150 clinical samples (urine, wound/pus, sputum and burn-wound) were tested. Isolates were isolated, tested for antimicrobial susceptibility, categorized based on their MDR and tested for their capacity to form biofilm using a crystal violet microtiter assay. The evaluation of CFS activity was carried out by measuring MIC and MBC, inhibition of developing biofilms, reduction of preformed biofilms, viable-count measurements as appropriate and combination testing with selected antibiotics. The statistical analyses performed were adequate parametric or non-parametric tests, correlation analysis and effect size estimation. The results offer experimental data on the possible complementary anti-biofilm effect of probiotics metabolites against MDR P. aeruginosa, with final interpretations limited to the available laboratory data.