Tolong jelaskan mengenai Penyebab dari Pencemaran sayur bayam di Amerika Utara 2006 dalam bahasa melayu

Wabak itu dijejak kepada beg plastik bayam segar. Dua syarikat di California telah menarik kembali bayam dan barangan mengandungi bayam secara sukarela: Natural Selection Foods LLC, berpengkalan di San Juan Bautista, dan River Ranch Fresh Foods.  Natural Selection brands include Natural Selection Foods, Pride of San Juan, Earthbound Farm, Bellissima, Dole, Rave Spinach, Emeril, Sysco, O Organic, Fresh Point, River Ranch, Superior, Nature's Basket, Pro-Mark, Compliments, Trader Joe's, Ready Pac, Jansal Valley, Cheney Brothers, D'Arrigo Brothers, Green Harvest, Mann, Mills Family Farm, Premium Fresh, Snoboy, The Farmer's Market, Tanimura & Antle, President's Choice, Cross Valley, and Riverside Farms. Affected brands from River Ranch include Hy-Vee, Farmer's Market and Fresh and Easy. Kemudiannya, syarikat ketiga, RLB Food Distributors, Pantai Barat Amerika, menarik kembali keluaran mengandungi bayam kerana dikuatiri mengandungi pencemaran E. coli.