Anti-bacterial and anti-biofilm activity of bacteriophages against Klebsiella pneumoniae and Pseudomonas aeruginosa isolated from orthopedic patients

Objective. To investigate the susceptibility of K. pneumoniae and P. aeruginosa to a polyvalent bacteriophage preparation and its effect on biofilm formation and the strain biofilms isolated from orthopedic patients.Materials and methods. The research sample included 50 clinical isolates of K. pneumoniae and 50 clinical isolates of P. aeruginosa. Identification was performed by MALDI-TOF-MS; antibiotic susceptibility was assessed in accordance with EUCAST v 21. Detection of carbapenemase genes was carried out by real-time PCR. The strain susceptibility to the bacteriophage was determined by a spot test; K. pneumoniae ATCC 33495 and P. aeruginosa ATCC 27853 were determined by assessing their growth curves. Biofilms of strains sensitive to bacteriophages were formed according to the O’Toole method by co-incubation of bacteria with phages. The effect of bacteriophages on 24-hour biofilms was assessed by comparing the optical density of dye extracts of bacteriophage-treated wells and control wells at 570 nm. The data were analyzed using the Statistica environment.Results. It was found that 7 (14%) of K. pneumoniae and 15 (30%) of P. aeruginosa were resistant to carbapenems. Six strains of K. pneumoniae produced NDM-cabapenemase, while four isolates of P. aeruginosa produced VIM-carbapenemases. The bacteriophage preparation under study was active against 36% and 56% of K. pneumoniae and P. aeruginosa strains, respectively. The majority of the studied strains reduced biofilm production upon co-incubation with a phage; however, a decrease in biomass of greater than 80% was observed only for P. aeruginosa. The effect of the bacteriophage on the already formed biofilms was less pronounced, despite a decrease in the biofilm biomass in 78% and 68% of K.pneumoniae and P. aeruginosa strains, respectively.Conclusion. The results obtained confirm the need for further research into the action of bacteriophages against pathogens caused by implant-associated infections and the development of bacteriophage therapy for orthopedic patients.