A New Approach for Phage Cocktail Design in the Example of Anti-Mastitis Solution

The studies on phage therapy have shown an overall protective effect of phages in bacterial infections, thus providing an optimistic outlook on the future benefits of phage-based technologies for treating bacterial diseases. However, the therapeutic effect is highly affected by the proper composition of phage cocktails. The rational approach to the design of bacteriophage cocktails, which is the subject of this study, allowed for development of an effective anti-mastitis solution, composed of virulent bacteriophages acting on <i>Escherichia coli</i> and <i>Staphylococcus aureus</i>. Based on the in-depth bioinformatic characterization of bacteriophages and their in vitro evaluation, the cocktail of five phages against <i>E. coli</i> and three against <i>S. aureus</i> strains was composed. Its testing in the milk model experiment revealed a reduction in the number of <i>S. aureus</i> of 45% and 30% for <i>E. coli</i> strains, and in the study of biofilm prevention, it demonstrated 99% inhibition of biofilm formation for all tested <i>S. aureus</i> strains and a minimum of 50% for 50% of <i>E. coli</i> strains. Such insights justify the need for rational design of cocktails for phage therapy and indicate the potential of the developed cocktail in the treatment of diseased animals, but this requires further investigations to evaluate its in vivo efficacy.