Bacteriophages of the arctic bacterium Staphylococcus borealis - isolation, host range and anti-biofilm effect The evaluation of efficacy, host range and anti-biofilm capacities of bacteriophages infectious to nosocomial staphylococcal strains

Abstract

As antibiotic resistance is on the rise in parallel with the stagnation of antibiotic discovery, the world urges for novel antibacterial strategies. Phage therapy has a century-long history of application in former Soviet countries in eastern Europe and has gained attention as a potential alternative to conventional antibiotics, with high specificity and low cytotoxicity. This study aimed at isolating lytic bacteriophages, infectious to the novel species Staphylococcus borealis and other strains of staphylococci. Since no novel lytic bacteriophages were isolated from Norwegian samples, the Belgian phages ISP, Huma and Romulus were assessed for host range and anti-biofilm effect in combination with antibiotics and antimicrobial peptides as a tool for combatting infection by coagulase negative staphylococci. The host range analysis showed the ability of the phage ISP to infect and kill S. borealis HUS23, being the first documented phage infection of this novel species. Biofilm assays showed the ability of ISP and the antimicrobial peptide StAMP9 to inhibit growth and reduce biofilm formation of S. borealis with 90.5%, but more knowledge should be gained on eradication of mature biofilm. Bioinformatic studies of the S. borealis type strain 51-48 (CCUG 73747) showed the presence of prophages in the genome, with the phage CNPH82 isolated from S. epidermidis as the best hit. To expand the pool of lytic bacteriophages infectious to S. borealis, more environmental and human samples should be processed for the isolation of novel phages. However, this study show that it could be possible to include S. borealis in the host range of phages of related host species such as S. aureus or S. epidermidis.