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FDA speaks: E. coli O157 in leafy greens

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Between August and December 2020, the U.S. Food and Drug Administration (FDA) and multiple state and federal partners were involved in an outbreak investigation related to E. coli O157:H7 illnesses and the consumption of leafy greens. The outbreak, which caused 40 reported domestic illnesses, was linked via whole genome sequencing (WGS) and geography to outbreaks traced back to the California growing region associated with the consumption of leafy greens in 2019 and 2018. FDA, alongside state and federal partners, investigated the outbreak to identify potential contributing factors that may have led to leafy green contamination with E. coli O157:H7. The E. coli O157:H7 outbreak strain was identified in a cattle feces composite sample taken alongside a road approximately 1.3 miles upslope from a produce farm with multiple fields tied to the outbreaks by the traceback investigations. In addition, several potential contributing factors to the 2020 leafy greens outbreak were identified.

Isolates within this cluster of illnesses are part of a reoccurring strain of concern and are associated with outbreaks that have occurred in leafy greens each fall since 2017. The two most recent outbreaks associated with this strain were an outbreak in 2018 (linked to romaine lettuce from the Santa Maria growing region of California) and an outbreak in 2019 (linked to romaine lettuce from the Salinas growing region of California). Clinical isolates from cases in this 2020 outbreak appear more closely related to those from the 2019 outbreak than the 2018 outbreak. In addition, several specific food and environmental isolates that appear to be highly related to this 2020 outbreak include a fecal-soil composite sample collected by FDA in February 2020 from the Salinas growing region and two leafy green samples collected in 2019 by state partners as a part of the 2019 investigation that traced back to the Salinas growing region.

As part of this investigation, tracebacks of leafy greens consumed by ten ill individuals from eleven points of service were conducted. Although that traceback investigation was based on a relatively small number of the total cases, it was based on those cases which presented the strongest evidence via purchase card information, invoices, bills of lading, and electronic data. The traceback investigation identified the Salinas growing region of California as a geographical region of interest.

In light of this most recent finding, combined with previous outbreak investigation findings in the region, FDA has identified key trends regarding the issues of a reoccurring strain, a reoccurring region, and reoccurring issues around adjacent and nearby land use of primary importance in understanding the contamination of leafy greens by E. coli O157:H7 that occurred in 2020 and previous years.

FDA also recognizes the interconnection between people, animals, plants, and their shared environment when it comes to public health outcomes. As such, we strongly encourage collaboration among various groups in the broader agricultural community (i.e. livestock owners; leafy greens growers, state and federal government agencies, and academia) to address this issue. With this collaboration, the agricultural community, alongside academic and government partners, can work to identify and implement measures to prevent contamination of leafy greens. FDA recommends that these parties participate in efforts to understand and address the challenge of successful coexistence of various types of agricultural industries to ensure food safety and protect consumers against foodborne illnesses.

Frank Yiannas, Deputy Commissioner for Food Policy and Response – Food and Drug Administration said in a release that as part of our ongoing efforts to combat foodborne illness, today the U.S. Food and Drug Administration published a report on the investigation into the Fall 2020 outbreak of Shiga Toxin-Producing E. coli (STEC) O157:H7 illnesses linked to the consumption of leafy greens grown in the California Central Coast. The report describes findings from the investigation, as well as trends that are key to understanding leafy green outbreaks that are linked to the California Central Coast growing region, specifically encompassing the Salinas Valley and Santa Maria growing areas every fall since 2017.

We released our preliminary findings earlier this year that noted this investigation found the outbreak strain in a sample of cattle feces collected on a roadside about a mile upslope from a produce farm. This finding drew our attention once again to the role that cattle grazing on agricultural lands near leafy greens fields could have on increasing the risk of produce contamination, where contamination could be spread by water, wind or other means. In fact, the findings of foodborne illness outbreak investigations since 2013 suggest that a likely contributing factor for contamination of leafy greens has been the proximity of cattle. Cattle have been repeatedly demonstrated to be a persistent source of pathogenic E. coli, including E. coli O157:H7.

Considering this, we recommend that all growers be aware of and consider adjacent land use practices, especially as it relates to the presence of livestock, and the interface between farmland, rangeland and other agricultural areas, and conduct appropriate risk assessments and implement risk mitigation strategies, where appropriate. Increasing awareness around adjacent land use is one of the specific goals of the Leafy Greens Action Plan we released last March, which we’re also announcing is being updated today to include new activities for 2021.

During our analysis of outbreaks that have occurred each fall since 2017, we have determined there are three key trends in the contamination of leafy greens by E. coli O157:H7 in recent years: a reoccurring strain, reoccurring region and reoccurring issues with activities on adjacent land. The 2020 E. coli O157:H7 outbreak associated with leafy greens represents the latest in a repeated series of outbreaks associated with leafy greens that originated in the Central Coast of California (encompassing Salinas Valley and Santa Maria) growing region (that’s me and Frank and the woman who wants to divorce me in our Kansas kitchen, 10 years ago)

In the investigation, the FDA recommends that growers of leafy greens in the California Central Coast Growing Region consider this reoccurring E. coli strain a reasonably foreseeable hazard, and specifically of concern in the South Monterey County area of the Salinas Valley. It is important to note that farms covered by the Food Safety Modernization Act (FSMA) Produce Safety Rule are required to implement science and risk-based preventive measures in the rule, which includes practices that prevent the introduction of known or reasonably foreseeable hazards into or onto produce.

The FDA also recommends that the agricultural community in the California Central Coast growing region work to identify where this reoccurring strain of pathogenic E. coli is persisting and the likely routes of leafy green contamination with STEC. Specifically, we have outlined specific recommendations in our investigation report for growers in the California Central Coast leafy greens region. Those recommendations include participation in the California Longitudinal Study and the California Agricultural Neighbors workgroup. When pathogens are identified through microbiological surveys, pre-harvest or post-harvest testing, we recommend growers implement industry-led root cause analyses to determine how the contamination likely occurred and then implement appropriate prevention and verification measures.

In response, Tim York wrote in The Packer that on April 16 the California LGMA Board took decisive action to endorse pre-harvest testing guidance. The guidance recommends pre-harvest testing specifically when leafy greens are being farmed in proximity to animal operations. 

It’s the intention of the board to include pre-harvest testing as part of the LGMA audit checklist so the government can verify that all LGMA members are in compliance. 

This is the first time an entire commodity group will be required to conduct pre-harvest testing.

This is a big deal, but a necessary response to the recent U.S. Food and Drug Administration report on outbreaks associated with lettuce in 2020.  The findings and regulatory language used by FDA in this report were nothing short of a warning shot that calls on our industry to do more to stop outbreaks. 

And so, we must do more.

Updating LGMA’s required food safety practices is an involved process that seeks input from scientists, food safety experts and the public. No other entity is capable of making such widespread change as quickly as we can.<

Some weeks ago, in the first piece I wrote for The Packer as CEO of the California LGMA, I stressed the need for collaboration with the retail and foodservice buying community, noting that we must lean on each other to make needed improvements together. And now, I am asking for your help.

Updating LGMA’s required food safety practices is an involved process that seeks input from scientists, food safety experts and the public. No other entity is capable of making such widespread change as quickly as we can.

35 in 11 states sick with E. coli from Romaine lettuce grown in Arizona

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It’s time to end the leafy greens cone of silence.

Top view of romaine lettuce that has been sliced on a wood cutting board.

This time it has made people unnecessarily sick.

I wouldn’t touch their product.

But how would I know?

On Sept. 14, 2006, the U.S. Food and Drug Administration announced that an outbreak of E. coli O157: H7 had killed a 77-year-old woman and sickened 49 others. The FDA learned from the Centers for Disease Control and Wisconsin health officials that the outbreak may have been linked to the consumption of produce and identified bagged fresh spinach as a possible cause.

Eventually, four would die and at least 200 sickened.

One of the responses was to form the Leafy Greens Marketing Agreement (LGMA) which apparently overseas most of the leafy greens production in the U.S.

They are known primarily for self-aggrandizing press releases.

And lots of rumors about how they inhibit epidemiological investigations into outbreaks of foodborne illness linked to their products (search ‘cone of silence’ on barfblog.com for plenty of examples)

According to the U.S. Centers for Disease Control, since the last update on April 10, 2018, 18 more people from 9 states were added to this outbreak.

How many of those could have been prevented if CDC or State health types fingered chopped Romaine lettuce when rumors started circulating? Is the goal of LGMA really to forego epi and demand absolute proof before going public?

As of April 12, 2018, 35 people infected with the outbreak strain of E. coli O157:H7 have been reported from 11 states. Illnesses started on dates ranging from March 22, 2018 to March 31, 2018. Ill people range in age from 12 to 84 years, with a median age of 29. Sixty-nine percent of ill people are female. Twenty-two ill people have been hospitalized, including three people who developed hemolytic uremic syndrome, a type of kidney failure. No deaths have been reported.

Illnesses that occurred after March 27, 2018, might not yet be reported due to the time it takes between when a person becomes ill with E. coli and when the illness is reported. This takes an average of two to three weeks.

Epidemiologic evidence collected to date indicates that chopped romaine lettuce is the likely source of this outbreak. Twenty-six (93%) of 28 people interviewed reported consuming romaine lettuce in the week before their illness started. This percentage is significantly higher than results from a survey[787 KB] of healthy people in which 46% reported eating romaine lettuce in the week before they were interviewed. Most people reported eating a salad at a restaurant, and romaine lettuce was the only common ingredient identified among the salads eaten. The restaurants reported using bagged, chopped romaine lettuce to make salads. At this time, ill people are not reporting whole heads or hearts of romaine.

Traceback investigations are ongoing to determine the source of chopped romaine lettuce supplied to restaurant locations where ill people ate. At this time, no common grower, supplier, distributor, or brand has been identified. However, preliminary information indicates that the chopped romaine lettuce was from the Yuma, Arizona growing region.

Information collected to date indicates that chopped romaine lettuce from the Yuma, Arizona growing region could be contaminated with E. coli O157:H7 and could make people sick.

Advice to Restaurants and Retailers:

  • Restaurants and retailers should not serve or sell any chopped romaine lettuce, including salads and salad mixes containing chopped romaine lettuce, from the Yuma, Arizona growing region.
  • Restaurants and retailers should ask their suppliers about the source of their chopped romaine lettuce.

That’s right, consumers, it’s up to you.

It should be up to the restaurant or retailer, who markets food safety at point-of-purchase.

And LGMA, which covers Yuma growing, should be forthcoming about risks, rather than blowing themselves in nonsensical tweets.

Lettuce grazers rejoice: Consumer Reports says it’s ok to eat romaine lettuce again

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Actually, it was the U.S.  Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) who jointly declared an end to the E coli O157 outbreak after nearly two months of investigation. At least 66 people across the U.S and Canada became ill, 22 were hospitalized, and 2 died during November and December, all linked to consumption of romaine lettuce.

Consumer Reports went along for the ride.

What’s been missing is any response from the leafy greens marketing agency types.

Silence – the LGMA cone of silence — is golden, I guess.

CDC announced on January 25, 2018, that this outbreak appears to be over, because the last case became ill on December 12, 2017. This indicates that the food causing illness is no longer available in the marketplace or consumers’ homes.

Although this outbreak appears to be over, the FDA’s outbreak investigation team is continuing to work with federal, state and local partners to determine what leafy greens made people ill, what people ate, where they bought it, and identify the distribution chain — all with the goal of identifying any common food or points where the food might have become contaminated. To date, no common link has been identified.

Because whole genome sequencing showed that the E. coli O157:H7 strain that resulted in the U.S. illnesses was closely related genetically to the strain that caused illnesses in Canada, the FDA and CDC have been in contact with Canadian food safety authorities throughout this outbreak.

 

58 sick, 2 dead, possible link to romaine lettuce

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Over the past seven weeks, 58 people in the U.S. and Canada have become ill and two have died from E. coli O157H7, linked by Canadians to romaine lettuce, probably grown in California, given the timing of illnesses.

On Dec. 11, 2017, the Public Health Agency of Canada did its public duty and notified Canadians that at least 21 people were sick with E. coli O157:H7 and the probable source was romaine lettuce.

A couple of retailers in Canada pulled all romaine lettuce from the shelves, but the others shrugged and said, not enough is known.

By Dec. 28, 2017, the Canadian numbers had jumped to 41 sick and one dead, and the U.S. Centers for Disease Control chimed in to say there were 17 sick in the U.S. with a similar strain but they wouldn’t say it was linked to romaine lettuce, with the Trumpesque language of “CDC is unable to recommend whether U.S. residents should avoid a particular food.”

Outbreaks are hard, but where’s the tipping point between protecting public health and protecting a commodity and all the growers, retailers, involved?

Everyone went off and enjoyed New Year’s, and then people woke up again on Jan. 2, 2018 (happy new year), to be told by the Toronto Star (that’s in Canada) that of the 17 U.S. cases, five people have been hospitalized, one of whom has died. Two have developed hemolytic uremic syndrome.

That’s 58 sick and two dead.

On Jan. 3, 2018, Trisha Calvo of Consumer Reports wrote the group’s food safety types advise “consumers stop eating romaine lettuce until the cause of the outbreak is identified and the offending product is removed from store shelves.”

“Even though we can’t say with 100 percent certainty that romaine lettuce is the cause of the E. coli outbreak in the U.S., a greater degree of caution is appropriate given that lettuce is almost always consumed raw,” says James Rogers, Ph.D., director of food safety and research at Consumer Reports.

“There is not enough epidemiologic evidence at this time to indicate a specific source of the illnesses in the United States,” says Brittany Behm, MPH, a CDC spokesperson. “Although some sick people reported eating romaine lettuce, preliminary data available at this time shows they were not more likely than healthy people to have eaten romaine, based on a CDC food consumption survey.” Health officials, Behm says, take action when there is clear and convincing information linking illness to a contaminated food.

“The FDA should follow the lead of the Canadian government and immediately warn the public about this risk,“ said Jean Halloran, Director of Food Policy Initiatives at Consumers Union, the policy and mobilization division of Consumer Reports.

“The available data strongly suggest that romaine lettuce is the source of the U.S. outbreak,” she says. “If so, and people aren’t warned, more may get sick.”

That got attention, and many media outlets chimed in.

barfblog.com’s Ben Chapman told Rachael Rettner of Live Science that, “[To] say ‘avoid romaine for now,’ I don’t know if I have enough information to agree with that statement,”  Benjamin Chapman, an associate professor and food safety specialist at North Carolina State University.

“Avoiding just romaine may or may not be enough,” because other lettuces or foods could also be affected, Chapman told Live Science. “It could be that there’s a different [food] source of this exact same pathogen,” he said.

Another possibility is that the E. coli strain causing illness in the United States is actually slightly different from the strain in Canada. “We could be looking at two different outbreaks at the same time,” Chapman said.

About four times a day I’ll get a tweet from the Leafy Green Marketing Agreement – the folks who set themselves up after the spinach outbreak of E. coli O157:H7 in 2006 that killed four and sickened 200 – blowing themselves about how great they are, and how their products are so safe.

If you want that kind of PR, then you have to take the hits as well.

LGMA never talks about an outbreak linked to leafy greens (publicly).

To me, they’ve succeeded best at lowering the leafy greens cone of silence and intimidating public health types into delaying reports of outbreaks.

But late on Jan. 4, 2018, LGMA finally made a public statement, below, with my comments.

A group of produce industry associations today issued the following statement to update consumers on a recent e.coli outbreak being investigated in Canada in the U.S.:

It’s E coli. You folks should be well-versed in that.

The U.S. Centers for Disease Control and Prevention has not identified what food likely caused this foodborne illness.  No public agency has contacted any Romaine lettuce grower, shipper or processor and requested that they either stop shipping or recall product already in the marketplace.

Defensive.

Even if this outbreak is actually confirmed to be caused by Romaine lettuce, it’s important to recognize this is a highly perishable product with a limited usable shelf life and it’s highly unlikely a specific affected lot would still be available for sale or in a home refrigerator with the last U.S. illness being reported on December 8th.

Carry on, it’s all gone.

Food safety remains a top priority of leafy greens farmers, shippers and processors and the industry has robust food safety programs in place that incorporate stringent government regulatory oversight.

The Pinto defense. Audits and inspections are never enough, and saying we have government oversight does nothing to build trust with the consuming public, as research shows.

Our leading produce industry associations have and will continue to cooperate fully with public health officials investigating this foodborne illness outbreak.

Play nice in the sandbox.

Anytime we see an outbreak of any foodborne illness, our hearts go out to the victims.

This is what you should have led with. Now it reads like a tack-on.

If the leafy green marketing folks want to be truly transparent, they will make actual inspection data public for mere mortals to review, they will market microbial food safety at retail, and stop stonewalling every time there is an outbreak linked to leafy greens.

I have lots of respect for individual farmers who make a go of it and produce the bounty of produce we enjoy.

I have no respect for self-serving associations with bad soundbites.

A table of leafy green related outbreaks is available at https://www.barfblog.com/wp-content/uploads/2018/01/lettuce-leafy-greens-outbreaks-table-_1-5-18.xlsx

Leafy green cone of silence: Salad producers say don’t be scared by ‘ridiculous’ study

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In a time when facts don’t matter and Donald Trump is President-elect, there is scrutiny of any new study, and rhetoric is increasingly common.

spongebob-oil_-colbert-may3_-10Socrates, via Plato, had some thought on rhetoric (yes I dabbled in philosophy many decades ago, didn’t everyone experiment in university?).

Still no comment from the Leafy Greens Marketing Agreement but they sent a few of their spokesthingies out to counter a study that says Salmonella grows in cut leafy greens, even at refrigerator temperatures..

Ashley Nickle of The Packer reports that Bruce Taylor, CEO and founder of Salinas, Calif.-based Taylor Farms, emphatically denounced the study.

“We find the artificial conditions created by this study to be ridiculous,” Taylor said in an e-mail. “Producers of bagged salads do not have ‘juice’ in the salad bag, and producers take painstaking steps to avoid the introduction of salmonella or any other pathogen.”

The conclusion regarding refrigeration was the only notable one in the study, said Trevor Suslow, a member of the technical committee of the Center for Produce Safety. Scientists would expect salmonella to be able to survive at the temperature recorded in the study but would not expect it to grow, he said.

“People will definitely be trying to reproduce their results as far as growth under refrigeration temperature for salmonella,” Suslow said. “That’s, for me, the key issue.”

Suslow, an extension research specialist at the University of California-Davis, said it is already known that a bagged salad is an environment in which salmonella can have the nutrients it needs to grow, which is why the industry has focused so intently on ensuring no pathogens make it into bags into the first place.

Drew McDonald, vice president of quality, food safety and regulatory affairs at Salinas-based Church Brothers Farms, said in an e-mail that, although the researchers did some things well, he also had some issues with the study.

“From my read, the study essentially grew salmonella in juices extracted from actual bagged salads in a mixture of sterile water,” McDonald said. “The issue is that in the ‘real’ world the salmonella has to come from somewhere (the surface of the leaf for example) but along with this would be many other microorganisms. That they were able to grow salmonella under these forced, artificial conditions without any competition from other organisms is not surprising.”

lettuceAlong with the growth conditions, the washed status of the lettuce also gave McDonald pause.

“From my understanding, (the) project used ‘bagged salad,’” McDonald said. “I am assuming this means it was already washed. The fact that they added salad juice and salmonella after it had already been bagged and washed really just shows how important it is to not cross-contaminate cleaned product.”

The researchers, as a result of their findings, suggested people eat bagged salads as soon as possible after purchase to minimize risk. They wrote in a question-and-answer supplement to the release that they no longer keep their bagged salads in the refrigerator longer than one day.

“Ridiculous recommendation,” Taylor said in his e-mail. “For 30 years consumers have enjoyed hundreds of millions of bagged salads weekly with great benefit to their health and wellbeing.”

Jennifer McEntire, vice president of food safety and technology at United Fresh Produce Association, also disagreed with the recommendation.

“People should always follow the instructions, including best-by dates, on packages, mainly so that they experience the best quality product,” McEntire said in an e-mail. “People shouldn’t be afraid to keep salad in their refrigerators for the full duration of the shelf life.”

She may mean use-by dates.

Suslow described the study as another piece of the puzzle in trying to find long-term solutions for food safety issues, but he was not impressed by it.

“Sort of generating a lot of additional concern and fear without any real basis for changing what (is) sort of standard practice isn’t necessarily helpful,” Suslow said. “Could hurt the category, but probably no more so than other things such as those instances when there are outbreaks or recalls.

“I think consumers understand that there’s no such thing as zero risk,” Suslow said (smartest thing anyone said in this story). “They understand and appreciate the convenience of packaged salads with multiple ingredients with very healthy mixed leafy greens, and that’s how the category has grown.”

Washing is futile: Leafy green cone of silence

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Lettuce is overrated.

lettuce-skullThat’s my response to people who ask about the proportionally high rates of foodborne illness in lettuce and other leafy greens eaten raw.

I like spinach – in a lasagna or stir-fry – but not raw.

Raw is risky.

There’s a bunch of new findings on foodborne pathogens and leafy greens which are summarized below.

In the sphere of public conversation, it is notable the Leafy Greens Marketing Agreement, the group formed after the 2006 E. coli-in-spinach outbreak that killed four and sickened at least 200 in the U.S. – has been once again silent on any research or outbreaks that associate risk with greens.

The leafy green cone of silence.

Investigations by University of Leicester microbiologists have revealed that just a small amount of damage to salad leaves can massively stimulate the presence of the food Salmonella in ready-prepared salad leaves.  

The scientists have discovered that juices released from damaged leaves also had the effect of enhancing the virulence of the pathogen, potentially increasing its ability to cause infection in the consumer.  

The research is led by Dr Primrose Freestone of the University’s Department of Infection, Immunity and Inflammation and PhD student Giannis Koukkidis, who has been funded by a Biotechnology and Biological Sciences Research Council (BBSRC) i-case Studentship.  

Their research investigates novel methods of preventing food poisoning pathogens from attaching to the surface of salad leaves to help producers improve food safety for consumers.

This latest study, published in Applied and Environmental Microbiology, found that juices from damaged leaves in bagged spinach and mixed salad increased Salmonella pathogen growth 2400-fold over a control group and also enhanced their adherence to surfaces and overall virulence, or capacity to cause disease.  

Dr Freestone said: “Salad leaves are cut during harvesting and we found that even microliters of the juices (less than 1/200th of a teaspoon) which leach from the cut-ends of the leaves enabled Salmonella to grow in water, even when it was refrigerated. These juices also helped the Salmonella to attach itself to the salad leaves so strongly that vigorous washing could not remove the bacteria, and even enabled the pathogen to attach to the salad bag container.  

“This strongly emphasizes the need for salad leaf growers to maintain high food safety standards as even a few Salmonella cells in a salad bag at the time of purchase could become many thousands by the time a bag of salad leaves reaches its use by date, even if kept refrigerated. Even small traces of juices released from damaged leaves can make the pathogen grow better and become more able to cause disease.  

 “It also serves as a reminder to consume a bagged salad as soon as possible after it is opened. We found that once opened, the bacteria naturally present on the leaves also grew much faster even when kept cold in the fridge.  

“This research did not look for evidence of Salmonella in bagged salads. Instead, it examined how Salmonella grows on salad leaves when they are damaged.”  

Leafy green and other salad vegetables are an important part of a healthy diet, providing vitamins, minerals, and dietary fiber. Ready to eat prepared salads are particularly popular, are widely consumed and so of significant economic importance. Over recent years there has however been a number of outbreaks associated with fresh salad produce contaminated with Salmonella and E. coli both in the USA and Europe. 

lettuce-harvestThis has triggered considerable interest in effective strategies for controls and interventions measures both in UK industry, the EU and key research funding bodies. 

Despite a number of published reports on improving the microbiological safety of salad leaf production, very few studies have investigated the behavior of Salmonella once the leaves have been bagged.  

Giannis said: “Anything which enhances adherence of foodborne pathogens to leaf surfaces also increases their persistence and ability to resist removal, such as during salad washing procedures.  Even more worrying for those who might eat a Salmonella contaminated salad was the finding that proteins required for the virulence (capacity to cause infection) of the bacteria were increased when the Salmonella came into contact with the salad leaf juices. “Preventing enteric pathogen contamination of fresh salad produce would not only reassure consumers but will also benefit the economy due to fewer days lost through food poisoning. We are now working hard to find ways of preventing salad-based infections.”  

No comment from the LGMA.

While this research may make it seem like pre-packaged salads pose a scary risk, the researchers themselves were quick to say they still eat bagged salads. But they make sure to look for packages that have appropriate use-by dates and crisp-looking leaves. They stay away from salads that have mushy, slimy-looking greens, or bags with accumulated salad juice at the bottom. And they make sure to eat the greens within one day of purchase.

“Our project does not indicate any increased risk to eating leafy salads, but it does provide a better understanding of the factors contributing to food poisoning risks,” said Freestone. 

If you feel like it, you can wash greens that have already been pre-washed by manufacturers just before eating, but Freestone says this doesn’t have much of an effect on the salmonella bacteria that may already be attached or internalized by the leaves. 

Her study was published in the journal Applied and Environmental Microbiology.

No comment from LGMA.

Assessment of irrigation water quality and microbiological safety of leafy greens in different production systems

Journal of Food Safety, 2 November 2016, DOI: 10.1111/jfs.12324

http://onlinelibrary.wiley.com/doi/10.1111/jfs.12324/abstract;jsessionid=883317B2001984CC39815B1792B68759.f04t01

Foodborne disease outbreaks associated with fresh produce irrigated with contaminated water are a constant threat to consumer health. In this study, the impact of irrigation water on product safety from different food production systems (commercial to small-scale faming and homestead gardens) was assessed.

spongebob-oil-colbert-may3-10Hygiene indicators (total coliforms, Escherichia coli), and selected foodborne pathogens (Salmonella spp., Listeria monocytogenes, and Escherichia coli O157:H7) of water and leafy green vegetables were analyzed. Microbiological parameters of all irrigation water (except borehole) exceeded maximum limits set by the Department of Water Affairs for safe irrigation water. Microbial parameters for leafy greens ranged from 2.94 to 4.31 log CFU/g (aerobic plate counts) and 1 to 5.27 log MPN/100g (total coliforms and E. coli). Salmonella and E. coli O157:H7 were not detected in all samples tested but L. monocytogenes was present in irrigation water (commercial and small-scale farm, and homestead gardens).

This study highlights the potential riskiness of using polluted water for crop production in different agricultural settings.

No comment from LGMA.

Adaptive response of Listeria monocytogenes to heat, salinity and low pH, after habituation on cherry tomatoes and lettuce leaves

PLOS

Sofia V. Poimenidou, Danai-Natalia Chatzithoma, George-John Nychas, Panagiotis N. Skandamis

http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0165746

Pathogens found on fresh produce may encounter low temperatures, high acidity and limited nutrient availability. The aim of this study was to evaluate the effect of habituation of Listeria monocytogenes on cherry tomatoes or lettuce leaves on its subsequent response to inhibitory levels of acid, osmotic and heat stress.

Habituation was performed by inoculating lettuce coupons, whole cherry tomatoes or tryptic soy broth (TSB) with a three-strains composite of L. monocytogenes, which were further incubated at 5°C for 24 hours or 5 days. Additionally, cells grown overnight in TSB supplemented with 0.6% yeast extract (TSBYE) at 30°C were used as control cells. Following habituation, L. monocytogenes cells were harvested and exposed to: (i) pH 3.5 adjusted with lactic acid, acetic acid or hydrochloric acid (HCl), and pH 1.5 (HCl) for 6 h; (ii) 20% NaCl and (iii) 60°C for 150 s.

Results showed that tomato-habituated L. monocytogenes cells were more tolerant (P < 0.05) to acid or osmotic stress than those habituated on lettuce, and habituation on both foods resulted in more stress resistant cells than prior growth in TSB. On the contrary, the highest resistance to heat stress (P < 0.05) was exhibited by the lettuce-habituated L. monocytogenes cells followed by TSB-grown cells at 5°C for 24 h, whereas tomato-habituated cells were highly sensitized. Prolonged starvation on fresh produce (5 days vs. 24 h) increased resistance to osmotic and acid stress, but reduced thermotolerance, regardless of the pre-exposure environment (i.e., tomatoes, lettuce or TSB).

lettuce-woolies-sep_-12-300x225These results indicate that L. monocytogenes cells habituated on fresh produce at low temperatures might acquire resistance to subsequent antimicrobial treatments raising important food safety implications.

No comment from LGMA.

Efficacy of post-harvest rinsing and bleach disinfection of E. coli O157:H7 on spinach leaf surfaces

Food Microbiology, April 2017, vol 62, pg 212-220, http://dx.doi.org/10.1016/j.fm.2016.10.019

Attachment and detachment kinetics of Escherichia coli O157:H7 from baby spinach leaf epicuticle layers were investigated using a parallel plate flow chamber. Mass transfer rate coefficients were used to determine the impact of water chemistry and common bleach disinfection rinses on the removal and inactivation of the pathogen. Attachment mass transfer rate coefficients generally increased with ionic strength. Detachment mass transfer rate coefficients were nearly the same in KCl and AGW rinses; however, the detachment phase lasted longer in KCl than AGW (18 ± 4 min and 4 ± 2 min, respectively), indicating that the ions present during attachment play a significant role in the cells’ ability to remain attached. Specifically, increasing bleach rinse concentration by two orders of magnitude was found to increase the detachment mass transfer rate coefficient by 20 times (from 5.7 ± 0.7 × 10−11 m/s to 112.1 ± 26.8 × 10−11 m/s for 10 ppb and 1000 ppb, respectively), and up to 88 ± 4% of attached cells remained alive.

lettuceThe spinach leaf texture was incorporated within a COMSOL model of disinfectant concentration gradients, which revealed nearly 15% of the leaf surface is exposed to almost 1000 times lower concentration than the bulk rinse solution.

No comment from LGMA.

Development of growth and survival models for Salmonella and Listeria monocytogenes during non-isothermal time-temperature profiles in leafy greens

Food Control, Vol 71, Part A, Jan 2017, Pg 32-41

http://dx.doi.org/10.1016/j.foodcont.2016.06.009

http://www.sciencedirect.com/science/article/pii/S0956713516303164

Leafy greens contaminated with Salmonella enterica have been linked to large number of illnesses in many countries in recent years. Listeria monocytogenes is also a pathogen of concern for leafy greens because of its prevalence in the growing and processing environment and its ability to grow at refrigeration temperatures. Experimental data for the growth and survival of S. enterica and L. monocytogenes under different conditions and storage temperatures were retrieved from published studies. Predictive models were developed using the three-phase linear model as a primary growth model and square-root model to calculate specific growth rate (ln CFU g−1 h−1) at different temperatures (°C). The square-root model for S. enterica was calculated as μ = (0.020(Temperature+0.57))2. The square-root model for L. monocytogenes was fitted as μ = (0.023(Temperature-0.60))2. The growth-survival model for S. enterica and growth model for L. monocytogenes were validated using several dynamic time-temperature profiles during the production and supply chain of leafy greens. The models from this study will be useful for future microbial risk assessments and predictions of behavior of S. enterica and L. monocytogenes in the leafy greens production and supply chain.

No comment from LGMA.

 

Is there a relation between the microscopic leaf morphology and the association of Salmonella and Escherichia coli O157:H7 with iceberg lettuce leaves?

Journal of Food Protection, Number 10, October 2016, pp. 1656-1662, pp. 1784-1788(5)

I Van der Linden, M  Eriksson, M Uyttendaele, F Devlieghere

http://www.ingentaconnect.com/content/iafp/jfp/2016/00000079/00000010/art00017

To prevent contamination of fresh produce with enteric pathogens, more insight into mechanisms that may influence the association of these pathogens with fresh produce is needed.

lettuce-washIn this study, Escherichia coli O157:H7 and Salmonella were chosen as model pathogens, and fresh cut iceberg lettuce was chosen as a model fresh produce type. The morphological structure of iceberg lettuce leaves (stomatal density and length of cell margins per leaf area) was quantified by means of leaf peels and light microscopy of leaves at different stages of development (outer, middle, and inner leaves of the crop) on both leaf sides (abaxial and adxial) and in three leaf regions (top, center, and bottom). The morphology of the top region of the leaves was distinctly different from that of the center and base, with a significantly higher stomatal density (up to five times more stomata), different cell shape, and longer cell margins (two to three times longer). Morphological differences between the same regions of the leaves at different stages of development were smaller or nonsignificant. An attachment assay with two attenuated E. coli O157:H7 strains (84-24h11-GFP and BRMSID 188 GFP) and two Salmonella strains (serovars Thompson and Typhimurium) was performed on different regions of the middle leaves. Our results confirmed earlier reports that these pathogens have a higher affinity for the base of the lettuce leaf than the top. Differences of up to 2.12 log CFU/g were seen (E. coli O157:H7 86-24h11GFP). Intermediate attachment occurred in the central region.

The higher incidence of preferential bacterial attachment sites such as stomata and cell margins or grooves could not explain the differences observed in the association of the tested pathogens with different regions of iceberg lettuce leaves.

No comment from LGMA.

The N.Y Times reports the one place the one place the Salinas Valley’s bounty of antioxidants does not often appear is on the tables of the migrant workers who harvest it.

sponge-bob-handwashingMore than a third of the children in the Salinas City Elementary School District are homeless; overall diabetes rates are rising and projected to soar; and 85 percent of farmworkers in the valley are overweight or obese, partly because unhealthy food is less costly, said Marc B. Schenker, a professor at the University of California, Davis, who studies the health of farmworkers.

No comment from LGMA.

Sponge Bob wants answers.

Floodwater, E. coli and leafy greens

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The California Leafy Green Products Handler Marketing Agreement (LGMA) requires leafy green crops within 9 m of the edge of a flooded field not be harvested due to potential contamination (California Leafy Green Products Handler Marketing Board, Commodity Specific Flood Safety Guidelines for the Production and Harvest of Lettuce and Leafy Greens, 2012). Further, previously flooded soils should not be replanted for 60 days.

lettuceIn this study, the suitability of the LGMA metrics for farms in the Mid-Atlantic region of the United States was evaluated. The upper end of a spinach bed (in Beltsville, MD) established on a −5% grade was flooded with water containing 6 log CFU/ml Escherichia coli to model a worst-case scenario of bacterial movement through soil. Escherichia coli prevalence in soil and on foliar tissue was determined by most probable number (MPN) analysis at distances up to 9 m from the edge of the flood for 63 days. While E. coli was quickly detected at the 9-m distance within 1 day in the spring trial and within 3 days in the fall trial, no E. coli was detected on plants outside the flood zone after 14 days. On day 63 for the two trials, E. coli populations in the flood zone soil were higher in the fall than in the spring. Regression analysis predicted that the time required for a 3-log MPN/g (dry weight) decrease in E. coli populations inside the flood zone was within the 60-day LGMA guideline in the spring but would require 90 days in the fall. Overall, data suggest that the current guidelines should be revised to include considerations of field and weather conditions that may promote bacterial movement and survival.

Metrics proposed to prevent the harvest of leafy green crops exposed to floodwater contaminated with Escherichia coli

Appl. Environ. Microbiol. July 2016 vol. 82 no. 13 3746-3753, DOI: 10.1128/AEM.00052-16

Mary Theresa Callahan, Shirley A. Micallef, Manan Sharma, Patricia D. Millner, Robert L. Buchanan

http://aem.asm.org/content/82/13/3746.abstract?etoc

The long and winding road of frozen spinach in organic, industrially-produced food

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It started on Sunday, when Amy’s Kitchen, of Petaluma, Calif., issued a voluntary recall of nearly 74,000 cases of products that may include frozen spinach potentially tainted with Listeria, such as include frozen vegetable lasagna, brown rice and vegetable bowls, and stuffed pasta shell bowls. The products were distributed nationwide in the U.S. and Canada.

spongebob.oil.colbert.may3.10Next up was Wegman’s Food Markets, an East Coast grocery chain, that on Monday issued a voluntary recall for about 12,500 packages of organic frozen spinach and said the spinach was supplied by Twin City Foods, of Stanwood, Washington.

A person who answered the phone at Twin City Foods on Monday told JoNel Aleccia of The Seattle Times it wasn’t clear that the company had supplied frozen spinach to Amy’s Kitchen. She said Twin Cities could not say what volume of product might have been contaminated with listeria and that owners were not prepared to make a statement. She declined further comment.

On Tuesday, Twin City Foods announced a recall of a bunch of products containing frozen spinach, that was used in a whole bunch of frozen products. Hence the rolling recalls.

Noteworthy: “The Recalled Product was supplied to Twin City Foods by Coastal Green Vegetable Company LLC of Oxnard, CA which initiated a recall of the bulk spinach on March 20, 2015 due to possible contamination with Listeria monocytogenes. Twin City Foods immediately notified all affected customers and initiated recalls of the retail packages on March 20, 2015.”

Cadia-frozen-spinach-labelCoastal Green spokesman Paul Fanelli said his company is cooperating with the Food and Drug Administration in the voluntary recall. Coastal Green has contacted “all the companies” who might have received the suspect spinach, he said. He declined to release the number of affected businesses.

No illnesses have been reported to date.

What is known about Coastal Green? Not much.

But their website says it got a superior rating by AIB (American Institute of Baking).

Oh-oh.

That’s a red flag.

Where was the spinach grown? Probably California. Where’s the Leafy Greens Marketing Association on this one?

Probably under the leafy greens cone of silence.

Did the Listeria contamination happen in the plant or in the field?

Who knows.

No one is confirmed sick – yet – so people will soon go on with their business and LGMA will continue to blow itself instead of taking on more substantive issues.

Market microbial food safety, not adjectives.

 

 

Evaluation? E. coli victims appeal to workers in LGMA training video

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Coral Beach of The Packer writes that victims of the 2006 E. coli outbreak linked to fresh spinach tell their stories in a new food safety training video co-produaced by the California Leafy Greens Marketing Agreement and the non-profit group STOP Foodborne Illness.

Lauren Bush tells her story in the video, describing how as a 20-year-old college student she contracted an infection from a spinach salad that ultimately sent her to the hospital with hemorrhaging and other severe symptoms.

“I’m so pleased with the video,” Bush said during a Nov. 19 Internet press conference. “I hope it reminds everyone who sees it of the importance of what they are doing. I know it must be a lot of extra work, but it does save lives.”

Dan Sutton, LGMA member and general manager of Pismo Oceano Vegetable Exchange, said he attended a training session a week before the press conference and watched the reactions of people seeing it for the first time.

“There was absolute silence when it was over,” Sutton said. “It had an impact.”

The video is bilingual with segments presented in Spanish and English.

Respectable Leafy greens food safety hucksterdum

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To finish my tri-part Rolling-Stones inspired critique of leafy greens bullshit –outbreaks are only confirmed with direct testing and Bill Keene would be rolling in his grave — the Leafy Green Marketing Agency has done what all bureaucracies do:

Made a website.

With a dollop of PR hackerdom and an underpinning of how to tell the story better – tell the story better — The California Leafy Greens Marketing Agreement (LGMA) has updated its website to provide easier access to news, information, and resources on leafy greens food safety and the program created in 2007.

The home page of the revised website takes users to the most current news item, highlights the organization’s current Twitter post, and is followed immediately by two of the most-visited sections of the website: the LGMA’s mandatory Food Safety Practices and its list of Certified LGMA Members.

With continual outbreaks involving dangerous pathogens on leafy greens., the California-based self-appointed Leafy Greens Marketing Association has been reduced to the tried, twisted and why not twerking, public relations strategy of telling the story better.

But good stories rely on good data, And consumers have no clue which companies are better at providing reduced E. coli or Salmonella spinach and lettuce.

Because they aren’t told.

Early research/North American outbreaks

Fresh fruits and vegetables were identified as the source of several outbreaks of foodborne illness in the early 1990s, particularly leafy greens (Table 1).

Date Product Pathogen Cases Setting/dish State
Apr-92 Lettuce S. enteriditis 12 Salad VT
Jan-93 Lettuce S. Heidelberg 18 Restaurant MN
Jul-93 Lettuce Norovirus 285 Restaurant IL
Aug-93 Salad E. coli O157:H7 53 Salad Bar WA
Jul-93 Salad E. coli O157:H7 10 Unknown WA
Sep-94 Salad E. coli O157:H7 26 School TX
Jul-95 Lettuce E. coli O153:H48 74 Lettuce MT
Sep-95 Lettuce E. coli O153:H47 30 Scout Camp ME
Sep-95 Salad E. coli O157:H7 20 Ceasar Salad ID
Oct-95 Lettuce E. coli O153:H46 11 Salad OH
May-96 Lettuce E. coli O157:H10 61 Mesclun Mix ML
Jun-96 Lettuce E. coli O153:H49 7 Mesclun Mix NY

Table 1. Outbreaks of foodborne illness related to leafy greens, 1992-1996

Powell, D.A., Jacob, C.J. and Chapman, B. 2009. Produce in public: Spinach, safety and public policy in Microbial Safety of Fresh Produce: Challenges, Perspectives, and Strategies ed. by X. Fan, B.A. Niemira, C.J. Doona, F.E. Feeherry and R.B. Gravani. Blackwell Publishing, pp 369-384.

So, as could have been predicted 20 years ago, the California Leafy Greens Marketing Agreement (LGMA) has completely revised its website to provide easier access to a wealth of news, information and resources concerning leafy greens food safety, and this important program created in 2007

Why did it take the outbreak in the fall of 2006 to compel the leafy green types industry to embrace the kind of change the sector has heralded since 2007? And at what point will future evidence be deemed sufficient to initiate change within an industry in the future?

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