Understanding how pathogenic bacteria such as Listeria monocytogenes, Yersinia enterocolitica, and Salmonella can survive on surfaces commonly found in a meat processing environment is important for several reasons. It is necessary to gain knowledge of what is necessary for survival, where in the processing environment survival is most encouraged (walls, floors, machinery, etc.) and what the population dynamics of the organisms in these environments are. Does a bacterial population increase or decrease in numbers or will it remain constant? How long will it survive or how quickly will it increase? This information can help processors in determining how often to clean and sanitize and which surfaces and conditions might support bacterial survival more than others. It can also assist with respect to selection of appropriate surfaces when factory or processing equipment construction or renovation is being considered.
The results of our study show that on the four surfaces studied (stainless steel, acetal resin, fiberglass reinforced plastic wall paneling, and mortar), populations of the bacteria that were tested tended to either remain fairly constant or decline over the test period. The presence of pork serum provided increased survival, but not necessarily growth, over time. The temperature at which the surfaces and bacteria were incubated did not have much effect on the survival of the bacteria, with the exception that Yersinia enterocolitica was able to grow slowly on FRP at 10ºC over 15 days, but declined in numbers at 4ºC. Mortar was the most lethal of the four surfaces, most likely due to its high alkalinity (pH of about 12.5).
In conclusion, our study reveals that pathogens can survive for many days, even without the presence of nutrients and at refrigeration temperatures, on various surfaces. Therefore, prudent control over the processing environment through careful design and routine cleaning and sanitation are of vital importance in the prevention of contamination of product.