Raw is risky: Why salads are the biggest source of food poisoning and what to do to avoid it

Brian Adam of Intallght writes just over a year ago, the United States saw the largest outbreak of E. coli since 2006; affecting at least 98 people in more than 20 states. The origin wa bagged romaine lettuce. Unfortunately, this is not an isolated case. Vegetables and fresh fruit have become a real headache for food safety experts.

 Today in the United States, fresh vegetables are the largest source of food poisoning. In Europe, the figures are not so pristine, but the bacteria and viruses associated with this type of food also are to blame for the vast majority of poisonings. We are facing a real danger for food safety: salads.

The numbers speak for themselves

In 1990, more than 400 epidemic outbreaks associated with fresh fruits and salads were detected. Between 2001 and 2013 we are not even able to know in its entirety, some experts explain, how many related outbreaks appeared, but they are many, increasing since 2008. Arrived in 2013, in Europe these epidemics seem to reduce their growth, stagnating in number per year, as explained in this article by EFSA, the European authority on food safety.

Despite the fact that Europe the number of appearances seems to have stabilized, in the United States they have continued to increase. The danger is still lurking, hidden between “romaine lettuce and Brussels sprouts.” The reason is in “cool” words.

According to some independent experts, this increase could be related to the increased consumption of vegetables and fresh fruit in the diet. This is a consequence of the search for a better, healthier diet. But, not being processed, these foods can also bring unexpected and unpleasant surprises.

But what is the problem? What’s wrong with fresh vegetables? It is not that strict food safety controls do not pass, as it happens with everything that arrives at our supermarkets but fresh food, especially if we put it in a plastic bag, is cannon fodder for microorganisms.

From the duh files: FDA says cows may have caused E. coli lettuce contamination, gumshoes are needed

Lettuce and leafy greens are overrated.

Outbreaks of E. coli illness sickened 188 people last year who ate romaine lettuce in three separate outbreaks.

There have been so many outbreaks going back to spinach in 2006, and beyond that, my favorite salad now is a Greek  salad – without the lettuce.

If the Leafy Greens Marketing Association was as rigorous as its press releases maintain this would be minimized.

Instead, between 2009 and 2018, federal authorities identified 40 food-borne outbreaks of E. coli in the U.S. “with a confirmed or suspected link to leafy greens,” the FDA said.

Investigators concluded the most recent outbreaks were centered on ranches and fields owned by the same grower and that were located downslope from public land where cattle grazed.

So if LGMA is doing internal audits, why didn’t they notice this dude?

Because it’s PR not gumshoes, people out in the field.

We figured out 20 years ago that gumshoes are required.

 The U.S. Food and Drug Administration published the findings of an investigation into the contamination of romaine lettuce implicated in three outbreaks of E. coli O157:H7 during the Fall of 2019.

The investigation was conducted at several farms identified in the outbreak tracebacks, as well as at other businesses and public access areas and resulted in several key findings:

Each of these three outbreaks, identified in the report as Outbreaks A, B and C was caused by distinctly different strains of E. coli O157:H7 as determined by whole genome sequencing (WGS) analysis;

Traceback investigations of multiple illness sub-clusters and supply chain information identified a common grower with multiple ranches/fields which supplied romaine lettuce during the timeframe of interest to multiple business entities associated with all three outbreaks. 

The same strain of E. coli O157:H7 that caused Outbreak A was found in two different brands of fresh-cut salads containing romaine lettuce in 2019;

This same outbreak strain of E. coli O157:H7 in Outbreak A was detected in a fecal–soil composite sample taken from a cattle grate on public land less than two miles upslope from a produce farm with multiple fields tied to the outbreaks by the traceback investigations;

Other strains of Shiga toxin-producing E.coli (STEC), while not linked to any of the  outbreaks, were found in closer proximity to where romaine lettuce crops were grown, including two samples from a border area of a farm immediately next to cattle grazing land in the hills above leafy greens fields and two samples from on-farm water drainage basins.

These findings, together with the findings from earlier leafy greens outbreaks dating back to 2013, suggest that a potential contributing factor has been the proximity of cattle—a persistent source of E. coli O157:H7 and other STEC—to the produce fields identified in traceback investigations.

Because of  the reoccurring nature of outbreaks associated with leafy greens, the FDA recently released a 2020 Leafy Greens STEC Action Plan, which outlines a three-pronged approach for tackling this problem.  It describes the FDA’s plans for working with industry, federal partners, state and local regulators, academia and others to address the safety of leafy greens by advancing work in three areas: prevention, response, and addressing knowledge gaps.

Outbreak investigation of E. coli: Romaine from Salinas, California (November 2019)

21.may.20

FDA

https://www.fda.gov/food/outbreaks-foodborne-illness/outbreak-investigation-e-coli-romaine-salinas-california-november-2019

Salmonella in poop on produce

Heightened concerns about wildlife on produce farms and possible introduction of pathogens to the food supply have resulted in required actions following intrusion events. The purpose of this study was to evaluate the survival of Salmonella in feces from cattle and various wild animals (feral pigs, waterfowl, deer, and raccoons) in California, Delaware, Florida, and Ohio.

Feces were inoculated with rifampin-resistant Salmonella enterica cocktails that included six serotypes: Typhimurium, Montevideo, Anatum, Javiana, Braenderup, and Newport (104 to 106 CFU/g). Fecal samples were stored at ambient temperature. Populations were enumerated for up to 1 year (364 days) by spread plating onto tryptic soy agar supplemented with rifampin. When no colonies were detected, samples were enriched. Colonies were banked on various sampling days based on availability of serotyping in each state. During the 364-day storage period, Salmonella populations decreased to ≤2.0 log CFU/g by day 84 in pig, waterfowl, and raccoon feces from all states. Salmonella populations in cattle and deer feces were 3.3 to 6.1 log CFU/g on day 336 or 364; however, in Ohio Salmonella was not detected after 120 days. Salmonella serotypes Anatum, Braenderup, and Javiana were the predominant serotypes throughout the storage period in all animal feces and states. Determination of appropriate risk mitigation strategies following animal intrusions can improve our understanding of pathogen survival in animal feces.

Survival of salmonella in various wild animal feces that may contaminate produce, 01 April 2020

Journal of Food Protection

Topalcengiz Z1,2Spanninger PM3Jeamsripong S4,5Persad AK6,7Buchanan RL8Saha J2LeJEUNE J7Jay-Russell MT4,9Kniel KE3Danyluk MD2.

DOI:10.4315/0362-028X.JFP-19-302

https://www.ncbi.nlm.nih.gov/pubmed/32221570

(Oh, and I have a young lady who comes over every week for musical therapy, and we’ve been going through my greatest hits of the 1960s and 70s, so I just post whatever video I want now. Freedom of the press belongs to whoever owns one.)

Whittaker: Market food safety

Ashley Nickle of The Packer wrote in Oct. 2019 (did I mention the bit about catch up, 8 broken ribs and a broken collarbone) PMA chief science and technology officer Bob Whitaker gave an impassioned presentation at Fresh Summit on the improvements that need to be made in food safety across the industry. Ten years after the formation of the Center for Produce Safety, companies can’t assert anymore that there isn’t relevant research to inform practices, Whitaker said.

Whitaker gave specific examples of potentially risky practices that are common. He mentioned setting harvest containers on the ground before they’re filled, and spoke about relying on the presence of generic E. coli in agricultural water to indicate pathogenic E. coli, along with several other examples.

Whitaker encourages companies to get competitive on food safety if that will get them to push past the status quo. He urged industry members to consider the costs when outbreaks happen, and he mentioned the death of a toddler during the 2006 outbreak linked to spinach.

“If we look at the recent issues we’ve had, we had an issue that involved water,” Whitaker said. “People said, ‘Well, we measured the water, we looked at generic E. coli.’ Well yeah, but the research has told us for years that generic E. coli does not represent the presence of pathogenic E. coli or salmonella. And In fact, at the volumes we do, we’re not going to find it.

“We also know that in every water system we’ve looked at around the U.S., I don’t care what crop, it has nothing to do with crop, every place the researchers have looked at and we’ve had a concentrated effort, we found contamination in open water sources — back east, out west, up north, doesn’t make a difference,” Whitaker said. “That’s where it is.”

Growing near concentrated animal feeding operations is another practice that the research indicates carries some risk.

“We know that dust will make the stuff travel,” Whitaker said. “Now we don’t know how far, but we know the one experiment that was done went out to 600 and it was there, so maybe it went farther …”

He also noted several practices in the field that he described as problematic yet commonplace.

“If I had a nickel for every picture I get every summer of people showing me Port-A-Johns being serviced in the field next to a harvest crop, I could have retired a couple years ago,” said Whitaker, who plans to retire from PMA in January.

“Don’t tell me it doesn’t drip, and then we wonder how we get some of these things like parasites in our fields,” Whitaker said.

He mentioned harvest sleds being left in the field overnight with the day’s debris still on them as another potential problem.

 “I’m seeing companies now breaking away from what everybody else is doing and say, ‘You know what, this is what we’re going to do,’” Whitaker said. “And we’ve always abhorred that idea. We’ve always said that food safety is something we share with each other, we don’t compete on it.

“To hell with that,” Whitaker said. “One thing this industry knows how to do is compete … You’ve always been marketing it anyway — you know you have. I see the stories. I see myself show up in people’s marketing things to their customers. I know that they’re marketing that.

“So do it,” Whitaker said. “If that’s what it’s going to take to get better, to create competition to get better, then do it. Because that’s what we need to do. We need the impetus to do it.”

Persister, I don’t even know her: STEC in produce

Bacterial persistence is a form of phenotypic heterogeneity in which a subpopulation, persisters, has high tolerance to antibiotics and other stresses. Persisters of enteric pathogens may represent the subpopulations capable of surviving harsh environments and causing human infections. Here we examined the persister populations of several shiga toxin-producing Escherichia coli (STEC) outbreak strains under conditions relevant to leafy greens production.

The persister fraction of STEC in exponential-phase of culture varied greatly among the strains examined, ranging from 0.00003% to 0.0002% for O157:H7 strains to 0.06% and 0.08% for STEC O104:H4 strains. A much larger persister fraction (0.1–11.2%) was observed in STEC stationary cells grown in rich medium, which was comparable to the persister fractions in stationary cells grown in spinach lysates (0.6–3.6%). The highest persister fraction was measured in populations of cells incubated in field water (9.9–23.2%), in which no growth was detected for any of the STEC strains examined. Considering the high tolerance of persister cells to antimicrobial treatments and their ability to revert to normal cells, the presence of STEC persister cells in leafy greens production environments may pose a significant challenge in the development of effective control strategies to ensure the microbial safety of fresh vegetables.

Enhanced formation of shiga toxin-producing Escherichia coli persister variants in environments relevant to leafy greens production

Science Direct, Food Microbiology, Volume 84

Sandy Thao, Maria T. Brandl, Michelle Qiu Carter

https://www.sciencedirect.com/science/article/pii/S0740002018311353

Animals and produce-related risk: Australia New Zealand version

The Fresh Produce Safety Centre of Australia and New Zealand came out with an 8-page fact sheet on the risks of animals to fresh produce that was seven pages too long.

Chapman used to write wonderful 1-page fact sheets that were used around the world, and maybe he can be persuaded to do so again, or find a skilled student.

The important graphic is below. The rest is filler.



 

We’re all hosts on a viral planet: Phages to control Salmonella

Diets rich in minimally processed foods are associated with numerous health benefits, in part, due to their diverse, natural microbiota. However, antimicrobials, such as chlorine and peracetic acid (PAA), that are used to address food safety concerns may damage the natural microflora of fresh produce.

One promising approach for targeting pathogenic bacteria in foods without impacting the normal food microbiota are bacteriophages. In this study, we observed that combinational treatment of conventional antimicrobials (PAA and chlorine) and bacteriophages, specifically the Salmonella‐targeted preparation SalmoFresh, retained the bactericidal effectiveness of individual interventions, and in some cases, achieved substantially increased efficacy. Additionally, the bacterial microbiomes of farm fresh and organic produce were less affected after phage treatment compared to PAA and chlorine.

Finally, our study revealed that resistance rates against SalmoFresh were relatively minor and unaffected by the stresses introduced after chemical washes and/or bacteriophage treatment.

Treatment of fresh produce with a salmonella-targeted bacteriophage cocktail is compatible with chlorine or peracetic acid and more consistently preserves the microbial community on produce, 10 January 2020

Journal of Food Safety

Zachary D. Moye, Chythanya Rajanna Das, Jeffrey I. Tokman, Brian Fanelli, Hiren Karathia, Nur A. Hasan, Patrick J. Marek, Andre G. Senecal, Alexander Sulakvelidze

https://doi.org/10.1111/jfs.12763

https://onlinelibrary.wiley.com/doi/abs/10.1111/jfs.12763?af=R

Salmonella splashing on produce

Nearly one-half of foodborne illnesses in the United States can be attributed to fresh produce consumption. The preharvest stage of production presents a critical opportunity to prevent produce contamination in the field from contaminating postharvest operations and exposing consumers to foodborne pathogens. One produce-contamination route that is not often explored is the transfer of pathogens in the soil to edible portions of crops via splash water.

We report here on the results from multiple field and microcosm experiments examining the potential for Salmonella contamination of produce crops via splash water, and the effect of soil moisture content on Salmonella survival in soil and concentration in splash water. In field and microcosm experiments, we detected Salmonella for up to 8 to 10 days after inoculation in soil and on produce. Salmonella and suspended solids were detected in splash water at heights of up to 80 cm from the soil surface. Soil-moisture conditions before the splash event influenced the detection of Salmonella on crops after the splash events—Salmonella concentrations on produce after rainfall were significantly higher in wet plots than in dry plots (geometric mean difference = 0.43 CFU/g; P = 0.03). Similarly, concentrations of Salmonella in splash water in wet plots trended higher than concentrations from dry plots (geometric mean difference = 0.67 CFU/100 mL; P = 0.04).

These results indicate that splash transfer of Salmonella from soil onto crops can occur and that antecedent soil-moisture content may mediate the efficiency of microbial transfer. Splash transfer of Salmonella may, therefore, pose a hazard to produce safety. The potential for the risk of splash should be further explored in agricultural regions in which Salmonella and other pathogens are present in soil. These results will help inform the assessment of produce safety risk and the development of management practices for the mitigation of produce contamination.

Salmonella survival in soil and transfer onto produce via splash events

December 2019

Journal of Food Protection vol. 82 no. 12

DEBBIE LEE,1 MOUKARAM TERTULIANO,2 CASEY HARRIS,2 GEORGE VELLIDIS,2 KAREN LEVY,1* and TIMOTHY COOLONG3

https://doi.org/10.4315/0362-028X.JFP-19-066

https://jfoodprotection.org/doi/abs/10.4315/0362-028X.JFP-19-066?af=R

On-farm food safety more important: Does washing produce with anything actually work

Human norovirus (HuNoV) is a foremost cause of domestically acquired foodborne acute gastroenteritis and outbreaks. Despite industrial efforts to control HuNoV contamination of foods, its prevalence in foodstuffs at retail is significant. HuNoV infections are often associated with the consumption of contaminated produce, including ready-to-eat (RTE) salads.

Decontamination of produce by washing with disinfectants is a consumer habit which could significantly contribute to mitigate the risk of infection. The aim of our study was to measure the effectiveness of chemical sanitizers in inactivating genogroup I and II HuNoV strains on mixed salads using a propidium monoazide (PMAxx)-viability RTqPCR assay. Addition of sodium hypochlorite, peracetic acid, or chlorine dioxide significantly enhanced viral removal as compared with water alone. Peracetic acid provided the highest effectiveness, with log10 reductions on virus levels of 3.66 ± 0.40 and 3.33 ± 0.19 for genogroup I and II, respectively. Chlorine dioxide showed lower disinfection efficiency.

Our results provide information useful to the food industry and final consumers for improving the microbiological safety of fresh products in relation to foodborne viruses.

Effectiveness of consumers washing with sanitizers to reduce human norovirus on mixed salad

Eduard Anfruns-Estrada, Marilisa Bottaro, Rosa Pinto, Susana Guix, Albert Bosch

https://www.google.com/url?rct=j&sa=t&url=https://www.mdpi.com/2304-8158/8/12/637/pdf&ct=ga&cd=CAEYACoTMzg5Njg3MDc5MDQ0MzQ4MDY2MTIaYjhlODI0Y2UzN2MyNjM2MDpjb206ZW46VVM&usg=AFQjCNHrQjbPOtC5w9HRrDeMpQBa1mdgCw

FDA Frank: Digital prompts key to changing food safety behavior

Tom Karst of The Packer writes that teasing the details of a new era of smarter food safety, Food and Drug Administration deputy commissioner for food policy and response Frank Yiannas spoke Sept. 18 at the United Fresh Washington Conference.

Before coming to FDA last December, Yiannas was vice president of food safety at Walmart from 2008 to 2018.

And Disney in Orlando before that.

Yiannas said the FDA’s work on produce safety has been front and central to his work since he joined the agency.

He praised the industry for its contribution to food safety and said the public-private partnership on food safety efforts must strengthen even more in what he called a new era of smarter food safety that is set to begin in 2020.

“I was asked by the Commissioner to continue to lead our efforts on modernization,” Yiannas said. “We’ve come a long way since 2011, but there’s still work to be done.”

Tech-enabled traceability and tech-enabled outbreak response will be one area of focus for the new era of smarter food safety, Yiannas said.

While produce has an impressive safety record overall, he said there are weak points in the supply chain.

“What I have learned over the years, and especially from my vantage point with the world’s largest company, is that I do believe the food system’s Achilles heel is traceability and transparency,” he said.

He noted that in both the spinach-related foodborne illness outbreak in 2006 and the romaine-related outbreak in 2018, traceability was an issue.

“It seems eerily similar almost a decade later,” he said. “And we still are having to do these overly broad consumer advisories.”

Distributed ledger or blockchain technology can be part of the solution, he said, but that isn’t the focus.

“It is not about the technology— it is about solving some of our many public health challenges,” he said.

Helping efforts to create a culture of food safety among growers, food marketers, and consumers is another element of the new era plan, he said.

“What I’ve learned over the years, is that it’s impossible to make progress without changing and influencing behavior,” he said, noting the importance of “digital prompts” to encourage right behavior.

I agree.