The Seward Stomacher 400 Circulator has been used in a recent study¹ to evaluate environmental contamination by Listeria species. The increased interest in animal welfare and free range methods, such as pasture reared poultry, has made it important that there is a greater understanding of the ecology and epidemiology of Listeria in these systems. Listeria species are naturally present in the environment and can be isolated from pasture, fruit and vegetable crops. The extent to which farm animals reared in a free range environment are exposed and contaminated by these sources has been evaluated by a team from the Universities of Arkansas and Ithaca.The methodology developed by this team was intended to evaluate the level of contamination of the pasture by Listeria species occupied by free range poultry^[1]. Samples of grass and soil were collected from the pasture, both before and after introduction of the poultry, and processed using the Stomacher 400 Circulator to extract, culture and isolate the Listeria species present.

The environmental samples collected after introduction of poultry were significantly more likely to contain Listeria (P < 0.001). PCR tests found that both L. monocytogenes and L. innocua, including hemolytic L. innocua, were recovered from cecal, grass and soil samples. This has serious implications for the rate of contamination of free range poultry exposed to untreated pastures.

Stomacher® 400 Circulator is the Gold Standard of sample preparation in the food industry, but the same characteristics of performance, reproducibility and strength has diverse applications beyond the food microbiology laboratory. Soil, turf, faeces and clay have all been successfully processed. Seward can find references for diverse applications from their archives of 1000s of methods to support their customers.

Reference: ^[1] Listeria monocytogenes and hemolytic Listeria innocua in poultry. S. R. Milillo, J. C. Stout, I. B. Hanning, A. Clement, E. D. Fortes, H. C. den Bakker, H .Wiedmann and S. C. Ricke. Poultry Science, 2012 91:2158-2163