Bacteriophages for the Disruption of Pseudomonas aeruginosa Biofilms

Introduction: The use of antibiotics for the prevention and treatment of bacterial infections has a long-standing history. The success of antibiotics was initially due to the widespread susceptibility of bacteria to these agents, allowing their broad application in treating bacterial infections. However, currently, antibiotic therapy faces significant challenges, primarily due to global antibiotic resistance. One of the solutions to antibiotic resistance is the use of bacteriophages (phages). Bacteriophages are viruses that specifically target bacteria. Currently, numerous studies worldwide confirm the effectiveness of phage therapy. The advantages of using bacteriophages include their safety and absence of side effects. Bacteriophages do not affect the normal human microbiota. The formation of biofilms and their heightened antibiotic resistance necessitate considering bacteriophages as agents for biofilm destruction. To date, there are numerous publications evaluating the effectiveness of phages against biofilms. The aim of this study: to assess the efficacy of lytic bacteriophages in the destruction of P. aeruginosa biofilms. Methods: The study utilized 14 P. aeruginosa strains with high biofilm-forming capacity, isolated from patients in various hospitals. The efficacy of 4 Pseudomonas bacteriophages, isolated from clinical materials from patients in various hospitals in St. Petersburg, was studied. Biofilms were cultivated in 96-well polystyrene plates at 37°C for 5 days. The ability of bacteriophages to disrupt biofilms was evaluated by measuring the optical density (OD) using a spectrophotometer at a wavelength of 540 nm. For biofilm destruction, P. aeruginosa strains were treated with bacteriophages either once or multiple times (at the start of the experiment, and after 3, 6, and 9 hours). OD was assessed every three hours. Results: Biofilm samples not treated with phages maintained high OD throughout the experiment. The OD of biofilms treated with bacteriophages in different regimens (once or multiple times) significantly decreased from initially high values and remained low throughout the experiment. This effect was observed in the majority of studied strains (10 out of 14). Discussion: It is well-known that most chronic infections are associated with the formation of biofilms. Therapeutic doses of antibiotics are often incapable of disrupting biofilms. In this context, the search for alternative methods to combat biofilm-forming pathogens is a pressing task, especially in the face of global antimicrobial resistance. Bacteriophages have the ability to effectively degrade the biofilm matrix, and this property is utilized in phage therapy for both acute and chronic infections, including healthcare-associated infections. Our results confirm that phages can be successfully used for the treatment of infections caused by P. aeruginosa. Conclusions: The experiment demonstrated that both single and multiple applications of bacteriophages to P. aeruginosa biofilms promote their disruption. The growth of P. aeruginosa without suppression by bacteriophages contributes to further biofilm formation.