Optimizing Sampling Plans for Identifying Sources of Salmonella: An Example from a Multi-State Turkey Processing Plant Study

Salmonellosis and listeriosis are two of the leading diseases that are involved with food borne illness outbreaks. Both organisms can persist in a poultry processing environment and contaminate finished product if programs are not in place to limit their introduction and control their spread once introduced. Most processors conduct weekly microbial environmental testing as a check of their control methods. The positive or negative results from each sampling set are indicators of the current levels of microbial contamination, but an ongoing compilation of the results can provide a wide variety of other information. An example set of data was generated from environmental samples collected in poultry processing plants in five states that were analyzed for Salmonella and Listeria species, among other pathogens. A total of 1,363 samples were analyzed for both organisms and another 66 samples were analyzed for Salmonella alone (1,429 total). Of these, 284 (19.9%) were positive for Salmonella, 264 (19.4%) were positive for Listeria spp., and 54 (4%) were positive for both organisms. The data was compiled in Microsoft Excel and the PivotTable function was used to generate summaries and analyze the data for trends. These methods can provide valuable information for optimizing an environmental sampling plan to increase efficiency at finding positive results and decrease costs.