Potential role of refrigerated milk packaging in the transmission of listeriosis and salmonellosis

Cultures of three Listeria monocytogenes serotypes and three Salmonella spp. were applied to the exterior surfaces of waxed cardboard or plastic milk containers. Contamination sites were sampled with premoistened cotton swabs during 14 d of refrigeration. Unstressed cells of Listeria survived up to 14 d on the surfaces of waxed (1 serotype) and plastic (3 serotypes) containers. Heat-stressed cells of all three serotypes of Listeria survived for 2 d on both types of containers. One serotype survived for 4 d, but only on plastic containers. Unstressed cells of all three Salmonella strains survived up to 14 d on both types of containers. Heat-stressed Salmonella strains survived up to 2 d (waxed containers) and 4 d (plastic containers).