The mother of a 3-year-old boy who died from an untreated bacterial infection can continue with her apparent agency theory against Advocate Health and Hospital Corp. for the alleged negligence of an independently contracted doctor who treated the boy.In a written opinion Thursday, a panel of the 1st District Appellate Court reversed a ruling by Cook County Circuit Court Judge Preston Jones, Jr., that granted partial summary judgment to Advocate on the issue of apparent agency.The appeal presented a matter of first …