Your patient is an 18-year-old male who stepped on a nail in the barnyard. the nail penetrated his tennis shoe and punctured his foot. on your arrival, the patient has removed the nail and the shoe. the wound is about 2 mm in diameter with minor bleeding that has been controlled. the skin around the wound is red. the patient does not want to be transported but asks if you can give him "some ointment and a band-aid." you should explain to the patient that this type of injury is associated with an increased risk of: