[NOVEL APPROACH TO COMPOSITION OF, BACTERIOPHAGE MIXTURES FOR ANTIBACTERIAL THERAPY].

AIM: Evaluate antibacterial activity of an experimental mixture of phages, belonging to several well-studied species. MATERIALS AND METHODS: The study was carried out using a group of 55 clinical Pseudomonas aeruginosa strains of various origins,- 4 mono-species mixtures of 32 virulent bacteriophages (species phiKZ-, phiKMV-, phiPBl-, PaP3-like phages) and 2 novel phages, phiMK (species PaK-P2) and phiPerm5. Activity of preparations from mono-species mixtures of bacteriophages ofvarious species were compared with activity of 3 commercial mixtures. Standard methods of study of bacteriophages were used: determination of lytic activity by seeding onto bacterial lawns of P. aeruginosa, restriction analysis of phage DNA for confirmation of their be- longing to certain species. RESULTS: Cumulative activity of 6 mono-species mixtures of virulent phages was shown to be similar to lytic activity of commercial therapeutic mixtures used against P. aeruginosa infections. 54 of 55 strains of clinical isolates of P: aeruginosa showed sensitivity to experimental mixtures composed of mono-species mixtures of bacteriophages. 53 strains were lysed by commercial preparations. Wherein the possibility of accidental inclusion of moderate -bacteriophages in the experimental mixture is excluded. CONCLUSION: A possibility of creation of highly active therapeutic antibacterial preparations against P. aeruginosa using mono-species mixtures of 6 species of lytic bacteriophages is shown Use of such a mixture in therapy of lung infections reduces the risk of emergence of bacterial strains with increased virulence and patho- genicity during prolonged administration.

[Comparison of new giant bacteriophages OBP and Lu11 of soil pseudomonads with bacteriophages of phiKZ-supergroup of Pseudomonas aeruginosa].

Study of two recently isolated giant bacteriophages Lu11 and OBP that are active on Pseudomonas putida var. Manila and Pseudomonas fluorescens, respectively, demonstrated their similarity in morphology, genome size, and size of phage particles, with giant bacteriophages of Pseudomonas aeruginosa assigned to the supergroup of phiKZ-like phages of the family Myoviridae designated in this manner according to the best studied phage phiKZ that belongs to the species of this group widely distributed in nature. Comparison of major polypeptide sizes of mature particles suggests the similarity of certain proteins in the phages examined. In OBP particles visualized with an electron microscope, an "inner body" was detected, which points to the specific DNA package intrinsic to phages of phiKZ group. In the meantime, phages Lul11 and OBP do not exhibit resemblance among themselves or with any of earlier described phiKZ-like phages in respect to other traits; particularly, they have no detectable DNA homology. Note that phage Lu11 of P. putida var. Manila exhibits very slight homology with phage Lin68 of the family of P. aeruginosa phiKZ-like phages detected only in blot hybridization. This suggests the possible involvement of these phages in interspecies recombination ("gene shuffling") between phages of various bacterial species. Results of partial sequencing of phage genomes confirmed the phylogenetic relatedness of phage OBP to phages of the phiKZ-supergroup, whereas phage Lu11 most probably belongs to a novel species that is not a member of supergroup phiKZ composition. The results of the study are discussed in terms of the evolution of these phages.