Developing a risk management framework to improve public health outcomes by enumerating and serotyping Salmonella in ground turkey

Abstract

Salmonella enterica continues to be a leading cause of foodborne morbidity worldwide. A quantitative risk assessment model was developed to evaluate the impact of pathogen enumeration and serotyping strategies on public health after consumption of undercooked contaminated ground turkey in the USA. The risk assessment model predicted more than 20,000 human illnesses annually that would result in ~700 annual reported cases. Removing ground turkey lots contaminated with Salmonella exceeding 10 MPN/g, 1 MPN/g, and 1 MPN/25 g would decrease the mean number of illnesses by 38.2, 73.1, and 95.0%, respectively. A three-class mixed sampling plan was tested to allow the detection of positive lots above threshold levels with 2-6 (c = 1) and 3-8 samples per lot (c = 2) using 25-g and 325-g sample sizes for a 95% probability of rejecting a contaminated lot. Removal of positive lots with the presence of highly virulent serotypes would decrease the number of illnesses by 44.2-87.0%. Based on these model prediction results, risk management strategies should incorporate pathogen enumeration and/or serotyping. This would have a direct impact on illness incidence linking public health outcomes with measurable food safety objectives, at the cost of diverting production lots.

Risk assessment predicts most of the salmonellosis risk in raw chicken parts is concentrated in those few products with high-levels of high-virulent serotypes ofSalmonella

“…Yet this risk assessment suggests that most of the public health risk from chicken parts is concentrated in those rare products with high-levels of high-virulent serotypes. This conclusion is consistent with multiple previous risk assessments (Lambertini et al, 2019; Lambertini et al, 2021; Sampedro et al, 2024) for individual finished poultry products that build more detailed models of potentially confounding factors like lot-to-lot variation and imperfect testing. Our work advances these previous efforts by incorporating a serotype-specific DR approach based on epidemiological data and using more recent HACCP verification data that directly measure the high-level tail of the Salmonella contamination distribution.…”

“…This and another recent chicken parts QMRA (Lambertini et al, 2019) show that the risk is concentrated in products with the high-levels of Salmonella (products >1 MPN/g and >10 MPN/g), as do studies in ground turkey (Lambertini et al, 2021; Sampedro et al, 2024) and ground beef (Strickland et al, 2023). But all these studies model product contamination data collected using MPN method for the enumeration (in our case the Baseline parts survey data), which unfortunately has an upper limit of quantification lower than levels responsible for much of the risk (assay limit of 11 MPN/ml, here parts rinse, which translates to 2.4 CFU/g parts).…”

“…In the slightly more complex approach where we explicitly lowered the virulence of Kentucky, about two-thirds of the risk from high-level products was from high-virulent serotypes (26% of the 37% total). Two other risk assessments used a conceptually similar approach, assigning reduced virulence DR parameters to low-virulent serotypes though not just Kentucky, and reported a similar result that most illnesses were attributed to high- virulent serotypes in turkey (Sampedro et al, 2024) and beef (Strickland et al, 2023) products.…”

“…Obviously, perfect sampling and testing are neither realistic nor practical, but these results could then inform a plausible maximum effect of a test and reject strategy. Other risk assessments have extensively modeled the impacts of different within lot variability (Lambertini et al, 2019; Lambertini et al, 2021), and different sampling and testing plan assumptions (Sampedro et al, 2024), which can be seen as a way to put these ‘perfect test’ results into context.…”

“…Lambertini et al (2021) modeled ground turkey and suggested a similar result, that a microbial criterion of 1 cell/g for finished products would lead to an estimated 46.1% reduction in risk of illness. Another QMRA using ground turkey data showed removing ground turkey lots contaminated with above 10 MPN/g and 1 MPN/g will reduce illness about 38.2% and 73.1%, respectively (Sampedro et al, 2024). A QMRA for ground beef showed a small fraction of high-level products contaminated with above 10 MPN/g and 1 MPN/g contain about 13.6% and 36.7% of risks, respectively (Strickland et al, 2023).…”