PubMed:: "Enterocolitis, Necrotizing"[Mesh] OR "Enterocolitis, Pseudomembranous"[Mesh] OR;; ((pseudomembranous[tiab] OR necrotizing[tiab] OR necrotising[tiab]) AND enterocolitis[tiab]) OR nec[tiab];; Embase.com:: 'necrotizing enterocolitis'/exp OR 'pseudomembranous colitis'/exp OR ((pseudomembranous:ti,ab OR necrotizing:ti,ab OR necrotising:ti,ab) AND enterocolitis:ti,ab) OR nec:ti,ab;; Cochrane Library:: ((pseudomembranous OR necrotizing OR necrotising) AND enterocolitis) OR nec OR 'pseudomembranous colitis'