Modeling the Fate of Escherichia coli O157:H7 and Salmonella enterica in the Agricultural Environment: Current Perspective

Abstract

The significance of fresh vegetable consumption on human nutrition and health is well recognized. Human infections with Escherichia coli O157:H7 and Salmonella enterica linked to fresh vegetable consumption have become a serious public health problem inflicting a heavy economic burden. The use of contaminated livestock wastes such as manure and manure slurry in crop production is believed to be one of the principal routes of fresh vegetable contamination with E. coli O157:H7 and S. enterica at preharvest stage because both ruminant and nonruminant livestock are known carriers of E. coli O157:H7 and S. enterica in the environment. A number of challenge-testing studies have examined the fate of E. coli O157:H7 and S. enterica in the agricultural environment with the view of designing strategies for controlling vegetable contamination preharvest. In this review, we examined the mathematical modeling approaches that have been used to study the behavior of E. coli O157:H7 and S. enterica in the manure, manure-amended soil, and in manure-amended soil-plant ecosystem during cultivation of fresh vegetable crops. We focused on how the models have been applied to fit survivor curves, predict survival, and assess the risk of vegetable contamination preharvest. The inadequacies of the current modeling approaches are discussed and suggestions for improvements to enhance the applicability of the models as decision tools to control E. coli O157:H7 and S. enterica contamination of fresh vegetables during primary production are presented.

Persistence of Escherichia coli in the soil of an organic mixed crop‐livestock farm that integrates sheep grazing within vegetable fields

“…Weekly farm management practices and environmental parameters were not tracked in detail over the entire period of this current study. However, a more cohesive collection of these parameters, as well as projects conducted throughout different seasons, might illuminate other associations related to the peaks of generic E. coli MPN/g in the soil, as suggested by various authors (Fraser et al, 2013;Gorski et al, 2011;Ongeng et al, 2014;Reed-Jones et al, 2016;Salaheen et al, 2015). Warmer temperatures and precipitation occurring in the spring and summer have been shown in past studies to be correlated with increased incidence and survival of foodborne pathogens in the environment (Fraser et al, 2013;Gorski et al, 2011).…”

“…STEC is usually introduced into agricultural environments by livestock and/or wildlife faeces (Jay-Russell, 2013;Reed-Jones, Marine, Everts, & Micallef, 2016). Sheep are asymptomatic reservoirs of STEC and faecal shedding from ruminants may increase during periods of stress (Cooley et al, 2013;Edrington et al, 2009;Moynihan, Richards, Ritz, Tyrrel, & Brennan, 2013;Ongeng et al, 2014;Schilling et al, 2012). Raw manure deposited in production fields by grazing animals may introduce enteric foodborne pathogens into the growing environment and lead to increased contamination of produce, especially those high-risk crops that grow in contact with the soil, which then may become vehicles for these pathogens in the food supply (Gorski et al, 2011;Hoar et al, 2013;Niemira & Zhang, 2014;Salaheen et al, 2015;Strawn, Fortes, et al, 2013).…”

“…Research regarding the persistence of foodborne pathogens in the soil after a field is grazed by livestock is limited; thus, further research is necessary so that mixed crop‐livestock farmers can address on‐farm food safety issues involved with grazing production fields (Ongeng et al, ). This study represents the first part of a multi‐phase project to generate data regarding use of sheep grazing to prepare fields for fresh produce production and to reduce potential microbial food safety risks.…”

Salmonella persistence in soil depends on reciprocal interactions with indigenous microorganisms

“…There is reasonable body of evidence suggesting that Salmonella enterica adapts to different environments such as manure or soil (Semenov et al, 2010;Fornefeld et al, 2017). The fate of Escherichia coli and Salmonella in soil and soil-related environments was investigated in several studies (Ongeng et al, 2014;Mallon et al, 2015;Fornefeld et al, 2017;Wang et al, 2018). Furthermore, a number of studies have shown that the survival and success of an invader in a new (soil) environment depends on various biotic and abiotic factors.…”

Cooperation of Adhesin Alleles in Salmonella -Host Tropism

“…Each year, Salmonella enterica is responsible for 12 to 33 million human typhoid cases (2) and 1.3 billion cases of gastroenteritis worldwide (3), with approximately 3.5 million deaths. It is frequently the leading cause of foodborne infections in the United States annually (4) and a persistent agricultural problem, as Salmonella strains infect livestock (5); this in turn exposes humans to contaminated food sources (6). S. enterica subsp.…”