A system for the prevention of needle tract bacterial infections, in biopsy needle tracts, when these needles after having been inserted into a target tissue are withdrawn through tissues existing in the trajectory leading to the target tissue, comprising: - a metal percutaneous surgical instrument with a proximal end and an electrically conductive distal portion, including a distal end, percutaneously introducible into a tissue of a patient; - a contact electrode applicable to the skin of a patient; and - an electric current generator with a first terminal directly or indirectly connected to at least the distal portion of said instrument and a second terminal connected to said contact electrode, wherein - the instrument is a biopsy needle provided to prevent post-treatment bacterial infections when performing prostate biopsies, for which it comprises means for a massive and sudden release of metal ions comprising a metal coating the ions of which have antimicrobial properties with low toxicity for humans, arranged in at least the distal portion of said instrument, wherein said metal coating is configured, sized and provided so as to break down by means of electrochemical release when a current is applied thereto, releasing metal ions into its surroundings, which is said tissue when the instrument is introduced therein; and - said electric current generator is arranged and configured for generating a current and inducing the temporary circulation thereof between the instrument, the tissue and the contact electrode, respectively, with positive polarity in the first terminal and negative polarity in the second terminal, with an average current density measured on the surface in the percutaneously introducible portion of the instrument between 1 mA/cm 2 and 1000 mA/cm 2, preferably of substantially 10 mA/cm 2, with a magnitude of the current having an instantaneous value between 1 mA and 100mA and a duration of between 0.1 and 1000 seconds, preferably 0.1 and 10 seconds, to produce said massive and sudden release of the metal ions of the metal coating, wherein said metal coating is configured, sized and arranged so that at least 10 μg of metal per cm 2 of surface are broken down by means of said massive and sudden release of the metal ions during the time corresponding to said duration determined by use of the instrument, and wherein an ion environment with antimicrobial effect remains for hours or days once the instrument has been withdrawn from the patient. - a metal percutaneous surgical instrument with a proximal end and an electrically conductive distal portion, including a distal end, percutaneously introducible into a tissue of a patient; - a contact electrode applicable to the skin of a patient; and - an electric current generator with a first terminal directly or indirectly connected to at least the distal portion of said instrument and a second terminal connected to said contact electrode, - the instrument is a biopsy needle provided to prevent post-treatment bacterial infections when performing prostate biopsies, for which it comprises means for a massive and sudden release of metal ions comprising a metal coating the ions of which have antimicrobial properties with low toxicity for humans, arranged in at least the distal portion of said instrument, wherein said metal coating is configured, sized and provided so as to break down by means of electrochemical release when a current is applied thereto, releasing metal ions into its surroundings, which is said tissue when the instrument is introduced therein; and - said electric current generator is arranged and configured for generating a current and inducing the temporary circulation thereof between the instrument, the tissue and the contact electrode, respectively, with positive polarity in the first terminal and negative polarity in the second terminal, with an average current density measured on the surface in the percutaneously introducible portion of the instrument between 1 mA/cm 2 and 1000 mA/cm 2, preferably of substantially 10 mA/cm 2, with a magnitude of the current having an instantaneous value between 1 mA and 100mA and a duration of between 0.1 and 1000 seconds, preferably 0.1 and 10 seconds, to produce said massive and sudden release of the metal ions of the metal coating,