Pseudomonas aeruginosa as an opportunistic pathogen is particularly known for causing nosocomial infections in immune deficient individuals and presents resistance to many antibiotics. For this reason phage application is proposed as one of alternative therapies. However, no extensive research covering the impact of bacteriophages on specific changes in the genotype and phenotype of bacteria have not been carried out.
The aim of this study was to demonstrate that phage-resistant clones of P. aeruginosa PA01, show phenotypic changes impacting their virulence. Emerging clones were tested for phage sensitivity, profile of produced lipopolysaccharide, motility (twitching, swarming and swimming motility) and virulence in vivo in Galleria mellonella model.
The frequency of phage-resistant clones surviving treatment with selected lytic bacteriophages was estimated to about 50%. As a result of contact with the LPS-dependent phages (KT28, KTN6) the LPS O-specific chain length of isolates was reduced. In the case of fimbriae-dependent phages (KTN4, phiKZ) isolates displayed a reduced twitching motility.
The virulence of phage-resistant clones was conducted using G. mellonella model. The results of these experiments showed that the phenotypic changes preventing a phage infection, have reduced the virulence of bacterial isolates. The lifespan of infected larvae was extended from 24 to even 72 hours compared to wild PA01 strain. To complement these studies, later experiments concerning efficiency uptake of phagocytic cells as well as survival in macrophages will be assessed in THP-1 cell line. Moreover it is planned to evaluate the TLR and NOR stimulation in THP1-XBlue cell line.