Antibiotic Impregnation, Release, Activity, and Interaction With Porous Hydroxyapatite for Infectious Control in Neurotrauma Surgery

We demonstrated the antibiotic impregnation and release properties of four porous hydroxyapatite (HAp) materials with 40% or 50% porosity and different pore structures for infectious control in neurotrauma surgery. The antibiotics used were meropenem (MEPM), ceftriaxone sodium hydrate (CTRX), gentamicin sulfate (GM), and linezolid (LZD). Greater amounts of antibiotics could be impregnated into each HAp material by increasing the volume of the antibiotics using a simple impregnation method for 15 min at atmospheric pressure. Each material showed two antibiotic release patterns based on the type of antibiotic and their interaction with the material. The first was non-reactive release of MEPM and LZD, which plateaued on day 2 after an initial burst; the second was reactive release of CTRX and GM, which showed a two-phase release comprising an initial burst followed by sustained release from day 2. Almost all eluates showed antibacterial activity against Staphylococcus aureus, suggesting that any combination of materials and antibiotics examined can be used to prevent intraoperative infection during surgery. Notably, CTRX and GM, which showed sustained release for several days, may also be useful for infected cases, including control of wound infection around 48 h postoperatively.