MATERIALS AND METHODS: Twelve varieties of commercial wound coverings based on biopolymers of natural and synthetic origin, a biological preparation Staphylophag produced by scientific-industrial association Microgen (Russia), registration certificate P N001973/01, and the S. aureus 3196 test strain (GenBank JARQZO000000000) isolated from a patient with a burn wound have been used in our work. The ability of commercial biological wound coatings to absorb solutions was examined by immersing them in a physiological solution (pH 7.0-7.2) followed by weighing. The lytic activity of three bacteriophage series against the test strain was studied using the Appelman method and a spot test. The lytic activity of the bacteriophage in the wound samples was studied within 7 days after its absorption by the wound coatings.

RESULTS: The greatest volume of fluid was absorbed by the LycoSorb, NEOFIX FibroSorb Ag, Biatravm, and Chitocol-S wound coatings. All bacteriophage series have been found to have a high lytic activity against the test strain. It has also been shown that Chitocol-S, Collachit-FA, Algipran, and Aquacel Ag Extra possessed their own inherent antibacterial activity under in vitro conditions stable for 7 days; moreover, the lysis zones of the test strain increased after their saturation with bacteriophage. On day 0, a high level of bacteriophage lytic activity with the maximum size of the test strain lysis zones from 49 to 59 mm have been found to remain in all samples of the wound coverings. The bacteriophage activity persisted for 1 day in the samples of Hydrofilm, Polypran, and NEOFIX FibroCold Ag coatings, up to 4 days in Algipran, Nano-Aseptica, and Biatravm coatings; and for 7 days in the Chitocol-S, Collachit-FA, Opsite Post-Op Visible, NEOFIX FibroSorb Ag, Aquacel Ag Extra, and LycoSorb samples.

RESULTS: Twenty-five MRSA biofilm producers were used as substrates to isolate MRSA-specific phages. Despite the difficulties in obtaining an isolate of this phage, two phages (UPMK_1 and UPMK_2) were isolated. Both phages varied in their ability to produce halos around their plaques, host infectivity, one-step growth curves, and electron microscopy features. Furthermore, both phages demonstrated antagonistic infectivity on planktonic cultures. This was validated in an in vitro static biofilm assay (in microtiter-plates), followed by the visualization of the biofilm architecture in situ via confocal laser scanning microscopy before and after phage infection, and further supported by phages genome analysis. The UPMK_1 genome comprised 152,788 bp coding for 155 putative open reading frames (ORFs), and its genome characteristics were between the Myoviridae and Siphoviridae family, though the morphological features confined it more to the Siphoviridae family. The UPMK_2 has 40,955 bp with 62 putative ORFs; morphologically, it presented the features of the Podoviridae though its genome did not show similarity with any of the S. aureus in the Podoviridae family. Both phages possess lytic enzymes that were associated with a high ability to degrade biofilms as shown in the microtiter plate and CLSM analyses.