Application of hydroxyapatite as an innovative carrier for bacteriophages.

“Bacteriophage therapy” represents a valid approach against the spread of antibiotic-resistant bacterial strains but - at the same time - displays some disadvantages (low stability, short half-life, no resistance to acid pH condition), which make difficult phage delivery to the specific sites of infection such as the gastrointestinal environment. Since many years, hydroxyapatite is being explored as vehicle for drug targeting, transfection, bone scaffolds and implant coating materials and, for these reasons we evaluated the effect of this mineral for the bacteriophage therapy. The results have highlighted that Salmonella Rissen bacteriophage displays antimicrobial activity against ten Salmonella species isolated from food. Complexed with hydroxyapatite, the bacteriophages have shown an increased half-life and a resistance at acid pH conditions. Experiments have demonstratedthe ability of bacteriophages - carried by HA -to penetrate inside liver cancer cells (HepG2) more efficiently than phages alone and, so, killing in-tracellular bacteria. Furthermore, the hydroxyapatite/bacteriophage complex was able to reduce the bacterial load of Salmonella Rissen in previously infected minced meat, respect to bacteriophage or hydroxyapatite alone. Future research will be focused on the study of the effect of hydroxyapatite complexed with other bacteriophages.