Efficacy of Phage Cocktails Against Biofilms Formed by Antibiotic-Resistant Bacteria

Aim: The rapid spread of multidrug-resistant strains of Klebsiella pneumoniae and Pseudomonas aeruginosa, along with their ability to form biofilms on various medical devices, significantly complicate the treatment of infections caused by these microorganisms and render antibiotic therapy ineffective. In contrast, the use of bacteriophages is a promising alternative for combating antibiotic-resistant biofilm-forming strains of K. pneumoniae and P. aeruginosa. Methods: Two cocktails of 14 bacteriophages (nine Klebsiella phages and five Pseudomonas phages) were used to control biofilms formed by XDR (Extensively Drug-Resistant) strains of K. pneumoniae and P. aeruginosa under in vitro conditions. The K. pneumoniae strain harbored genes associated with biofilm formation fimH, mrkA, matBecp and antibiotic resistance blaNDM-1, blaKPC, blaOXA-48, blaCTX-M-1, blaTEM. The P. aeruginosa strain carried genes associated with biofilm formation algD, PslD, PelF and antibiotic resistance blaNDM-1. Bacteriophages were isolated from the wastewater samples. Biofilms were formed on various substrates (glass slides, wells of polystyrene plates, and polyvinyl chloride vascular catheters) and analyzed using optical and scanning electron microscopy, as well as gentian violet staining assays. Results: The results demonstrated that bacteriophage cocktails could effectively degrade biofilms of K. pneumoniae and P. aeruginosa. Biofilms formed on catheter segments, polystyrene plate wells, and glass slides were treated with lytic bacteriophages at concentrations of at least 10⁷ PFU/mL. After 24 h of treatment with phage cocktails, a 34. 5% reduction in biofilm biomass was observed on the catheters for K. pneumoniae strain No. 361 and 34. 1% for P. aeruginosa strain No. 7. In polystyrene plate wells, the reductions were 39. 3% and 52. 8%, respectively. Conclusion: The experimental results indicate the effectiveness of phage cocktails in reducing biofilm biomass and bacterial viability. Given the ability of phages to degrade biofilms, phage therapy may become a promising adjunct to standard treatment methods for infections caused by multidrug-resistant pathogens. Keywords: bacteriophages, biofilms, Klebsiella pneumoniae, Pseudomonas aeruginosa, antimicrobial resistance