Every person shall be regarded as practicing allopathic medicine within the meaning and provisions of this act, who shall append to his or her name the letters “M.D.”, “Physician” or any other title, letters or designation which represent that such person is a physician, or who shall for a fee or any form of compensation diagnose and/or treat disease, injury or deformity of persons in this state by any allopathic legend drugs, surgery, manual, or mechanical treatment unless otherwise authorized by law.