Employee was using a box end combination wrench to tighten the mounting bolts on a rotary feed chute. The wrench slipped off the nut, and caused The back of his left hand to strike the end of a protruding bolt. This casued a small abrasion. The emplyee self treated the injury on 02-10-09. On 02-13-09 the employee was sent to Concentra Medical for an infection/oral antibiotics