Listeria spp. transfers further from boots and wheels across flooring surfaces, compared with Salmonella, in the dairy context

Abstract

Listeria spp. and Salmonella are important foodborne pathogens to control; their likely dissemination on floor material in dairy processing plants via contaminated vectors, like manufacturing boots and trolley wheels, and in two matrix types (reconstituted skim milk and yoghurt) was therefore evaluated. The types of microorganisms present, matrices, and vectors all statistically significantly impacted the relationship between steps/wheel rotations and the resulting concentration of bacteria transferred. Trolley wheels were shown to transfer both pathogens over a greater distance than boots alone, based on a linear model; however, taking into account the median stride of an individual, operators wearing contaminated processing boots were estimated to disseminate Listeria further than Salmonella, particularly in a yoghurt matrix (550 m2). The dissemination of Listeria and Salmonella by movable vectors may account for the apparent re-occurrence of the same strains within food manufacturing environments that appear to be too distant from known harbourage niches.