Salmonella Prevalence Is Strongly Associated with Spatial Factors while Listeria monocytogenes Prevalence Is Strongly Associated with Temporal Factors on Virginia Produce Farms

Abstract

This study sought to examine different growing regions across the state of Virginia and to determine how factors associated with pathogen prevalence may differ between regions. Spatial and temporal data were modeled to identify factors associated with an increased pathogen likelihood in various on-farm sources.

Factors associated with foodborne pathogens and indicator organisms in agricultural soils

“…The goal was to understand how certain soil nutrients and/or properties may synergistically and/or antagonistically affect pathogen prevalence and indicator concentrations in soil. The prevalence of Salmonella, Listeria spp., and L. monocytogenes recovered in unamended soils was low, and also similar to a previous study conducted in Virginia, which also found low Salmonella and L. monocytogenes prevalence in the agricultural soils (0.5-1.8%) (Murphy et al, 2023). Interestingly, the prevalence of foodborne pathogens in unamended soils in the study reported here is lower than pathogen prevalence in amended soils reported in previous work (Gu et al, 2019;Hailu et al, 2021;Ferguson et al, 2023;Pires et al, 2023).…”

“…Additionally, the Salmonella serovar isolated from Farm B was not isolated from Farm C. These results suggest that diversity of Salmonella may differ by region; however, this finding may be an artifact of the small number of positive Salmonella samples in the reported study. This is supported by previous work that has shown Salmonella serovar diversity differs across regions, including interstate regions (Gorski et al, 2011;Strawn et al, 2014;Murphy et al, 2023).…”

“…These findings are of interest as produce grown and packed in the Coastal Plain region of Virginia have been implicated in Salmonella outbreaks associated with fresh produce (Greene et al, 2008;Bell et al, 2015). Previous research in this region of Virginia has also shown repeated isolation of Salmonella from environmental sources including sediment, water, soil, and wildlife (Greene et al, 2008;Gruszynski et al, 2014;Angelo et al, 2015;Bell et al, 2015;Truitt et al, 2018;Gu et al, 2019;Murphy et al, 2023). It has been hypothesized that Salmonella may be introduced to Coastal Plain soils by wildlife within the production environment (Greene et al, 2008;Gruszynski et al, 2014;Bell et al, 2015;Truitt et al, 2018;Gu et al, 2019).…”

“…prevalence in undisturbed soils from national parks, refuges, or non-agricultural areas (Liao et al, 2021). While previous studies have explored foodborne pathogen prevalence in agricultural soils (Moshtaghi et al, 2003;Rodriguez et al, 2006;Strawn et al, 2013a;Harrand et al, 2020;Ferguson et al, 2023;Murphy et al, 2023), minimal research exists on understanding how soil properties (e.g., macro-and micro-nutrients) impact foodborne pathogen prevalence in unamended agricultural soils. Since the survival and persistence of microorganisms can be impacted by the availability and composition of nutrient sources (Pike et al, 2019); as well as, prior work showing the association between Listeria spp.…”

Methodological differences between studies confound one-size-fits-all approaches to managing surface waterways for food and water safety

“…A 2020 review of agricultural water in the Southeastern United States noted that the geographical location of a water source played an important role in the prevalence and survival of foodborne pathogens ( 35 ). This conclusion is supported by other studies that compared microbial water quality between growing regions nationally ( 16 , 37 ) and locally ( 12 , 17 , 38 ), and between water types ( 32 , 39 – 41 ). Indeed, multiple studies have shown that this variability in water quality limits the efficacy of one-size-fits-all approaches to monitoring and mitigating microbial hazards in aquatic environments.…”