Tag Archives: Lettuce

Really: Is it safe to spin-dry leafy greens in a washing machine?

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Back when we started on our TV cooking video paper about 2000, we were appalled to watch a British celebrity cook drying carrots in the dryer.

Some of the nearly 1,000 small farmers in New England who grow leafy greens apparently dry the fresh veggies after a triple dip in water in a conventional home washing machine.

The spin cycle of a retrofitted washing machine wicks the water off the greens to dry and keep them fresher longer. This discovery by farmers offered a way to automate the drying process without investing in a prohibitively expensive, commercial-grade spinner. 

An important question lingers about this practice, which University of Massachusetts Amherst food scientists hope to answer: Is it safe?

“This has been a common practice among small producers of greens,” says Amanda Kinchla, a UMass Amherst extension associate professor of food science. “There are no regulations against this, but there is no data right now on the risk.”

Kinchla, a co-director of the USDA-funded Northeast Center to Advance Food Safety, and UMass Amherst food science colleagues Lynne McLandsborough and Matthew Moore have received a $71,000 grant from the Massachusetts Department of Agricultural Resources and the U.S. Department of Agriculture to study and address the microbial safety risks of processing leafy greens in washing machines. The Northeast Center to Advance Food Safety, led by the University of Vermont, promotes food safety education and technical support to small- and medium-size producers and processors in the northeast region.

The UMass Amherst team is building on work at the University of Vermont Extension, where the agricultural engineering program has been conducting workshops and creating posters for farmers on how to follow a hygienic design to convert washing machines into greens spinners and use them safely.

“My work is more impactful if I can address real-world stakeholder issues and leverage what already has been done,” Kinchla says.

Andrew Chamberlin, UVM Extension agricultural engineering technician, explains that bacteria and grime have the potential to accumulate if farmers don’t know how best to spin the greens and clean the machines. “We are trying to share best practices for food production,” he says.

For example, placing the greens in baskets that fit inside the machine results in fewer points of contact, reducing the risk of contamination, compared with putting the greens directly into the washing machine.

Kinchla’s team has converted four washing machines, based on Chamberlin’s directions, to study in the lab how contamination may occur, what kinds of microbes are present and how best to safely maintain, clean and sanitize the machine.

“We are examining whether the spin cycle on a washing machine has any more risk than commercially available, post-harvest leafy greens spinners,” Kinchla says.

Lettuce is overrated: FDA’s leafy greens STEC action

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I’ll say it again, as a comic in all seriousness: Lettuce is overrated.

My favorite salad is a Greek one with all those veggies and no lettuce.

The U.S. Food and Drug Administration announced last week that between 2009 and 2018, FDA and the Centers for Disease Control and Prevention (CDC) identified 40 foodborne outbreaks of Shiga toxin-producing E. coli (STEC) infections in the U.S. with a confirmed or suspected link to leafy greens.

Holy shit.

This is why The Tragically Hip were so great, and why they never appealed much beyond Canada.

I feel the same about academia.

And why Osterholm called me 15 years ago as a consultant for Fresh Express, and asked me how dare I the lettuce and skull picture, and I said because I can and it was fairly apt given there have been 40 outbreaks.

Holy shit (this is me echoing my John Oliver voice).

Coronavirus is just confirming: Go public, go often, go hard.

It’s the only way people will pay attention.

And as this story in the N.Y. Times points out, there have been spectacular public health failures by people who tell others, just shut the fuck up.

According to the FDA, it has an unwavering commitment to advancing the safety of fresh leafy greens. Leafy greens are among the most widely consumed vegetables and an important part of an overall healthy diet. While millions of servings are consumed safely every day, this produce commodity has been implicated too often in outbreaks of foodborne illness, and we believe that FDA, along with leafy greens sector stakeholders, can do more.

Between 2009 and 2018, FDA and Centers for Disease Control and Prevention (CDC) identified 40 foodborne outbreaks of Shiga toxin-producing E. coli (STEC) infections in the U.S. with a confirmed or suspected link to leafy greens. While most strains of E. coli are harmless, STEC can cause bloody diarrhea, anemia, blood-clotting problems, and kidney failure – conditions that are potentially life-threatening. The most common STEC, E. coli O157:H7, is the type most often associated with outbreaks.

Most leafy greens are grown outdoors, where they are exposed to soil, animals, and water, all of which can be a source of pathogen contamination. In addition, leafy greens are mostly consumed raw, without cooking or other processing steps to eliminate microbial hazards. The Produce Safety Rule under the FDA Food Safety Modernization Act (FSMA) sets science-based standards to help ensure that water, soil amendments (e.g., fertilizer or compost), food contact surfaces and other materials that touch produce during growing, harvesting, packing, and holding do not contribute to produce contamination. The Produce Safety Rule also addresses animal intrusion into fields and worker hygiene.

Due to the recurring nature of outbreaks associated with leafy greens, FDA has developed this commodity-specific action plan. What follows is an overview of the actions FDA plans to take in 2020 to advance work in three areas: (1) prevention, (2) response, and (3) addressing knowledge gaps.

E. coli persisters

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Escherichia coli O157:H7 (EcO157) infections have been recurrently associated with produce. The physiological state of EcO157 cells surviving the many stresses encountered on plants is poorly understood. EcO157 populations on plants in the field generally follow a biphasic decay in which small subpopulations survive over longer periods of time. We hypothesized that these subpopulations include persister cells, known as cells in a transient dormant state that arise through phenotypic variation in a clonal population.

Using three experimental regimes (with growing, stationary at carrying capacity, and decaying populations), we measured the persister cell fractions in culturable EcO157 populations after inoculation onto lettuce plants in the laboratory. The greatest average persister cell fractions on the leaves within each regime were 0.015, 0.095, and 0.221%, respectively. The declining EcO157 populations on plants incubated under dry conditions showed the largest increase in the persister fraction (46.9-fold). Differential equation models were built to describe the average temporal dynamics of EcO157 normal and persister cell populations after inoculation onto plants maintained under low relative humidity, resulting in switch rates from a normal cell to a persister cell of 7.7 × 10−6 to 2.8 × 10−5 h−1. Applying our model equations from the decay regime, we estimated model parameters for four published field trials of EcO157 survival on lettuce and obtained switch rates similar to those obtained in our study. Hence, our model has relevance to the survival of this human pathogen on lettuce plants in the field. Given the low metabolic state of persister cells, which may protect them from sanitization treatments, these cells are important to consider in the microbial decontamination of produce.

IMPORTANCE Despite causing outbreaks of foodborne illness linked to lettuce consumption, E. coli O157:H7 (EcO157) declines rapidly when applied onto plants in the field, and few cells survive over prolonged periods of time. We hypothesized that these cells are persisters, which are in a dormant state and which arise naturally in bacterial populations. When lettuce plants were inoculated with EcO157 in the laboratory, the greatest persister fraction in the population was observed during population decline on dry leaf surfaces. Using mathematical modeling, we calculated the switch rate from an EcO157 normal to persister cell on dry lettuce plants based on our laboratory data. The model was applied to published studies in which lettuce was inoculated with EcO157 in the field, and switch rates similar to those obtained in our study were obtained. Our results contribute important new knowledge about the physiology of this virulent pathogen on plants to be considered to enhance produce safety.

Formation of Escherichia coli O157:H7 persister cells in the lettuce phyllosphere and application of differential equation models to predict their prevalence on lettuce plants in the field

08 November 2019

Applied and Environmental Microbiology

Daniel S. Munther, Michelle Q. Carter, Claude V. Aldric, Renata Ivanek, Maria T. Brandl

DOI: 10.1128/AEM.01602-19

https://aem.asm.org/content/86/2/e01602-19.abstract?etoc

As romaine problems continue, US FDA takes closer look

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Chris Koger of The Packer writes the U.S. Food and Drug Administration will be collecting romaine samples in California and Arizona for a year to test for salmonella and E. coli following several foodborne outbreaks linked to the lettuce.

The new program begins this month, according to the FDA, citing two E. coli outbreaks in 2018 linked to romaine, and another one in October that was suspected to be from the leafy green. In its notice on the surveillance program, the FDA also cited a 2012 Salmonella Newport outbreak from romaine.

“Consistent with the FDA’s mission to protect consumers, if one of the target pathogens is detected as a result of this assignment, the agency will perform whole genome sequencing of the microorganism’s DNA to determine its virulence and whether it is genetically related to isolates causing human illness,” according to the notice.

 All samples will be tested before processing to allow the FDA to quickly find the point of origin, which has been problematic in recent outbreaks as public and federal health agencies traced lettuce through the supply chain. In part, traceability hurdles have led to the FDA’s New Era of Smarter Food Safety program, which tasks the industry with enhancing traceability methods and technology.

Trimmed and washed lettuce will be tested, but not fresh-cut lettuce, and no lettuce at the farm-level will be involved in the surveillance program.

Samples will be targeted at facilities and farms identified in the outbreaks starting in 2017, including wholesalers, foodservice distribution centers, and commercial cooling and cold storage facilities, according to the FDA notice.

Lettuce continues to be overrated: 7 sick in Maryland from E. coli linked to pre-packaged salad

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The Maryland Department of Health says seven confirmed cases of E. coli infections have been linked to pre-packaged Caesar salads.

According to the department of health, the infections were identified in people who’d eaten Ready Pac Bistro Bowl Chicken Caesar Salad purchased at Sam’s Club stores in Maryland.

One person was hospitalized as a result of the E. coli O157 infection.

No deaths have been linked to it.

And there aren’t enough bagpipes and mandolins in rock.

At least 30 sickened: Multistate outbreak of listeriosis associated with packaged leafy green salads, United States and Canada, 2015-2016

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We investigated an outbreak of listeriosis detected by whole-genome multilocus sequence typing and associated with packaged leafy green salads. Nineteen cases were identified in the United States during July 5, 2015–January 31, 2016; isolates from case-patients were closely related (median difference 3 alleles, range 0–16 alleles). Of 16 case-patients interviewed, all reported salad consumption. Of 9 case-patients who recalled brand information, all reported brands processed at a common US facility.

The Public Health Agency of Canada simultaneously investigated 14 cases of listeriosis associated with this outbreak. Isolates from the processing facility, packaged leafy green salads, and 9 case-patients from Canada were closely related to US clinical isolates (median difference 3 alleles, range 0–16 alleles). This investigation led to a recall of packaged leafy green salads made at the processing facility. Additional research is needed to identify best practices and effective policies to reduce the likelihood of Listeria monocytogenes contamination of fresh produce.

CDC

Julie L Self, Amanda Conrad, et al

https://wwwnc.cdc.gov/eid/article/25/8/18-0761_article?deliveryName=DM4960

Ontario parents speak out after 2-year-old’s E. coli linked death

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I seemed to have missed this, which is inexcusable, volunteer or not, medical stuff for me or not, but here it is, a month later (and if I did publish it, shows where my brain is going).

Avis Favaro of CTV News reported in early May that it all started with a romaine salad.

Kristen and Brad Bell felt a little sick after eating the salad last October.

Their two-year-old son soon started to show more severe symptoms. Cooper Bell was vomiting. He developed diarrhea. Then his mother noticed the blood in his diaper.

“I had no idea [what] was happening,” Kristen Bell told CTV News from her home in Stirling, Ont.

“I thought ‘This is not normal.'”

An emergency room doctor thought Cooper might have contracted a bacterial infection. The family’s pediatrician agreed, saying the Bells should keep their son hydrated and bring him back in the morning.

Soon after the Bells returned home, they noticed some worrying changes in Cooper’s behavior.

“He wasn’t responding to me the same as he was earlier. It wasn’t long after that, that he had a seizure in Brad’s arms,” Kristen Bell said.

Seeing their son shaking uncontrollably with his eyes closed, the Bells called an ambulance. He spent a few hours in hospital in nearby Belleville, Ont., and was then airlifted to the Children’s Hospital of Eastern Ontario in Ottawa.

Doctors at CHEO diagnosed Cooper with kidney failure brought on by E. coli. He suffered cardiac arrest and died. The Bells believe it was the romaine lettuce that made Cooper sick, although they were unable to send the lettuce for testing to confirm their belief because it had been thrown out.

There were 29 illnesses and 10 hospitalizations reported across Canada during last fall’s E. coli outbreak, according to the Public Health Agency of Canada. It was one of three outbreaks in North America over the past year all of which were linked to romaine lettuce.

Keith Warriner, a food safety expert and professor at the University of Guelph in Ontario, said in an interview that the food industry has long been slow to improve its testing practices something that could improve overall food safety, but would mean extra costs for their operations.

“The industry itself has known for many years what it needs to do, but it’s just been reluctant to do it,” he said.

The Bells agree. They’re sharing their story of grief with the hope it will help hospital workers and other parents better understand the danger of E. coli, but also because they want to see changes at the food production level.

“E. coli shouldn’t be in our food,” Brad Bell said.

“The way that we’re growing food is dangerous, and something has to change.”

Can you hear me know? The new holiday tradition: Searching for recalls and outbreak information

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Longtime friend of the barfblog.com, Michéle Samarya-Timm, health educator at the Somerset County Department of Health (that’s in New Jersey, represent) writes:

Baking pumpkin pies with Aunt Kay’s secret recipe.  Watching Miracle on 34th Street.  Preparing the dining room with the good china.  Diffusing political conversations at the dinner table. 

Some traditions give a sense of warmth, connection, and continuity, and regularly define a family’s holiday. Unfortunately, there is now a need to add an additional tradition to the season – actively checking for foodborne outbreaks and recalls to prevent folks from getting sick.

 Last week, on Tuesday, November 20th at 2pm, (two days before Thanksgiving), the CDC posted a media statement with advice to consumers, restaurants, and retailers: 

 “CDC is advising that U.S. consumers not eat any romaine lettuce, and retailers and restaurants not serve or sell any, until we learn more about the outbreak.”

 The need to release such a notice, right before a major holiday is an unpropitious scenario.  It was also very concerning in its specificity to consumers, retailers and restaurants:

“Wash and sanitize drawers or shelves in refrigerators where romaine was stored.”

Such an alert is most effective if it reaches the intended audiences.   Folks at my holiday table did not hear about the outbreak.  Neither did many local health departments.

Issuing media releases is one way for public health agencies to reach large groups of people. However, distracted by holiday preparations, travel, shopping, family, football and bad weather this advisory was only partially disseminated to the public. A person had to be following news outlets or social media to receive timely notice. I heard about the recall from the woman next to me while I was getting a haircut – not from the CDC or FDA, or any other federal or state agency.   

 It’s disturbing. The CDC could have sent this info directly to local health departments, or notify them that a news release was issued. This was not the first time as a local public health official that I received delayed – or no – official communication about a national foodborne issue.

Local public health professionals rely on communications systems established by federal and state oversight agencies. Most commonly, if a verified or suspect foodborne contamination or outbreak has occurred, the Centers for Disease Control and Prevention (CDC), the U.S. Department of Agriculture, or the U.S. Food and Drug Administration (FDA) will ascertain the appropriateness of information release. If this information is deemed credible, notification is forwarded individually or en masse to state departments of health. The states, in turn, push this information down to local regulators. Each step in the process contains elements that may delay the rapid dissemination of outbreak information. The ability and willingness of all stakeholders to quickly and readily share incident particulars with fellow responding agencies can enhance effectiveness and amplify response efforts.

Electronically sending this advisory directly to the nearly 3,000 local health departments in the US would provide the opportunity for hundreds of health inspectors, health educators, epidemiologists and other to reach the hospitals, food banks, schools, mom and pop establishments and local residents who may not have otherwise received the alert. This was a missed opportunity, and hopefully one that didn’t cause additional cases of illness.

As I’ve written before, coordinated communication strategies within and between public health agencies is less robust than it should be. As a result, state and local public health officials may hear about foodborne disease issues first from other sources, such as the media, word of mouth, public complaints, or the food industry.   

 We need to learn how to communicate better with each other.  Local public health shouldn’t have to keep an eye on the news media, Twitter or Facebook for information pertinent to protecting the people in our jurisdictions.  A multitude of electronic portals exist for purposes of interagency  communication, CDC, FDA, and the public health system should collectively define how pertinent information – such as this romaine advisory – rapidly and routinely gets to the grass roots public health workforce. Continuously improving interagency coordination and communication is a goal that is fundamental to increasing the effectiveness of this nation’s food safety systems. I’m putting this out there, because I’m willing to help with the solution. That way, in future years, I can spend my holidays perfecting Aunt Kay’s pie recipe.

This holiday, I’m thankful for public health influencers and amplifiers – like barfblog.com – that act as outbreak aggregators, and push out info to local public health types like me.   

Some background information and recommendations on this topic can be found in:  Getting the message across: an analysis of foodborne outbreak communications between federal, state, and local health agencies   https://calhoun.nps.edu/handle/10945/49379