Sugar? Really??

I've been reading through a book called Do-It-Yourself Medicine, written by Ragnar Benson and published by Paladin Press in Boulder, Colorado. In the chapter on stitching wounds, he states that after washing out the wound with Betadine, "[if] available, treat with Betadine ointment, mastitis medication, tetracycline ointment, or common powdered sugar." Say what? Powdered sugar as an antibiotic? A quick Google search on the subject didn't turn up any substantiation for this as an effective use. Why would sugar help keep infection at bay?