The investigators enrolled fifty patients undergoing spinal surgery were randomly divided in two subgroups (A and B) of 25 patients each. In subgroup A, wounds were irrigated with dilute (3%) povidone-iodine solution through a low-pressure pulsatile device. In subgroup B wounds were irrigated with normal saline solution thorough a bulb syringe. In both subgroup specimens for bacterial culture were harvested by swabs from surgical site before and after irrigation of the wounds.