Probiotics as an alternative to eliminate Pseudomonas aeruginosa biofilm.

Pseudomonas aeruginosa is a clinically important opportunistic pathogen characterized by high antibiotic resistance and strong biofilm-forming capacity, posing a major therapeutic challenge, particularly in immunocompromised patients. In this study, we aimed to evaluate the antibiotic resistance profiles and biofilm-forming abilities of clinical isolates, and to investigate the antibiofilm potential of the probiotic strain Lacticaseibacillus rhamnosus. A total of 66 clinical isolates were analyzed, revealing high levels of antibiotic resistance, while 87.9% of isolates demonstrated biofilm-forming capacity. Treatment with L. rhamnosus at 25% and 50% concentrations resulted in significant antimicrobial and antibiofilm effects. MIC and antibiofilm assays indicated that these effects were dose- and cell density-dependent. Scanning electron microscopy analyses confirmed the structural disruption of biofilms following treatment. Furthermore, real-time PCR results demonstrated that the expression levels of key biofilm-associated genes (algD, pelF, pslD, ppgl, and PAPI-1) were reduced by more than 50%. Importantly, this study provides evidence that L. rhamnosus can effectively inhibit both biofilm formation and biofilm-associated gene expression in multidrug-resistant P. aeruginosa isolates, highlighting its potential as a promising alternative or adjunctive biocontrol strategy against biofilm-related infections. These findings contribute to the growing body of research on probiotic-based approaches targeting antimicrobial resistance and biofilm-associated pathogenicity.