Tag Archives: leafy greens

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.

Where’s the leafy greens lobby? Feds to seek listeria, leafy green connections after Dole outbreak

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Mike Hornick of The Packer writes that health officials will begin routinely asking listeria outbreak victims if they consumed leafy greens, according to the Centers for Disease Control and Prevention.

lettuce.skull.noroThe addition of leafy greens to the standard federal questionnaire on listeria comes in response to last winter’s outbreak linked to a Dole Fresh Vegetables salad plant in Springfield, Ohio. That outbreak sickened 33 in the U.S. and Canada and was tied to at least one death. Dole stopped production in January and reopened the plant in April.

It was the first reported listeria outbreak in the U.S. associated with leafy greens, and the eighth with fresh produce. All occurred since 2008, according to an Aug. 26 report by the CDC.

“It is unclear whether the appearance of these outbreaks might be attributed to improved outbreak detection, changes in consumer behavior, or changes in production and distribution,” the report says. “Fresh produce processors are advised to review food safety plans and consider incorporating measures to avoid the growth and persistence of listeria.”

In the Ohio centered outbreak, the older questionnaire failed to identify a common source for seven infections reported by Nov. 30.

Then in December and January, eight new or previously interviewed patients or their representatives took part in open-ended interviews or provided shopper card records.

That revealed the connection. All reported consuming leafy greens in the month before the onset of illness.

Among these, seven reported romaine and six reported spinach, higher than national food consumption estimates of 47% and 24%, respectively. Six patients recalled consuming packaged salad, according to the report.

Dole Fresh Vegetables denied responsibility in two foodborne illness lawsuits that followed the outbreak.

Washing salad is no magic bullet; safe sources matter

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I’ve become increasingly fond of the convenience of pre-washed, bagged, fresh salad mix. A staple of my weekly meals is 4oz of steak, a crumble of blue cheese, grilled mushrooms, sliced pear, a few walnuts all over a bed of 50/50 mix of pre-washed baby spinach and and mesclun mix.

I just open the bag and throw the salad on the plate.contVis_mesclun

Because there’s not much I can do, safety-wise, to it once it’s in my home. If there’s pathogenic E. coli, Listeria or Salmonella there (or others) I’m stuck with it. I’m following recommendations from a bunch of my food safety friends who reviewed the literature on cut, bagged, washed, ready-to-eat leafy greens from a few years ago.

In the abstract, they write:

The panel concluded that leafy green salad in sealed bags labeled “washed” or “ready-to-eat” that are produced in a facility inspected by a regulatory authority and operated under cGMPs, does not need additional washing at the time of use unless specifically directed on the label.

Leafy green food safety risks need to be addressed before they get to me, all I can do by washing it again is increase the chance I cross-contaminate the salad precursor in my home. My purchasing choice is based in trust that growers, packers and processors know what they are doing, and do it. But at best, they can only remove 90% of what is there with a wash.

Some folks, according to BBC News, disagree. They say things like:

‘washing foods is not 100% fail-safe, but it gives people the best chance against infection.’

and

‘we always wash everything, especially if we’re going to eat it raw. We don’t use much bagged salad or spinach, but if we did, we would definitely wash it.’

I’ll stick with the science.

But what exactly are the best ways to wash your greens? The BBC asked two food industry professionals for the best practice in food safety and hygiene when it comes to salad and vegetables.

Camilla Schneideman worked in the food industry for 18 years having run her own restaurants abroad and in the UK, and is currently the managing director of the Leiths Cookery School in London.

Rosalind Rathouse is a professional cook with more than 50 years of experience, who runs the Cookery School in central London.

Ms Rathouse advises storing all salad and vegetables in a cold environment, because it slows down the rate at which bacteria multiply.

What about ready-to-eat pre-packed salads?

Pre-packed salads are often washed in a low-chlorine solution to kill off the bugs, according Ms Schneideman, so eating straight from the bag is unlikely to harm you.

“It comes down to personal choice whether you want to give it an extra wash,” she said.

Soaking stuff all together also seems like a recipe for cross contamination. If I am washing something I’m going to rinse it down the drain.

Rewashing triple-washed greens at home can only increase risk of foodborne illness

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Keeping with the pathogen-in-leafy-greens theme of the night, I buy the triple washed and the never washed types of lettuce. My decision is usually based on how much we’ll consume in the next few days. I rinse the not washed. For the triple-washed type I open the bag and consume.

Stephen Kearse of Slate asks, What does “triple-washed” actually mean? And why do salad-green producers brag about washing their lettuce not twice, not four times, but three times in particular?USC1009846_026

I initially took my questions to salad-green producers themselves. Of the few companies that responded, most were tight-lipped. “We don’t discuss our business practices,” I was told by the PR director of Trader Joe’s, as if I were a rival firm rather than a customer. “Unfortunately we won’t be able to participate with input for your article,” I was told by the communications director of Dole, as if talking about food were beyond the scope of Dole’s business interests.

Earthbound Farms and Ready Pac were less reserved, offering to take some of my questions and answering them through email, but these exchanges were chillingly mediated, routed through an opaque infrastructure of internal approvals. The answers I received seemed like they had been triple-washed themselves, scrubbed of any negative (or meaningful) content. “From planting to harvest, each stage is inspected and audited to ensure it meets our strict food safety standards,” Earthbound told me. “Ready Pac Foods has long been at the forefront of innovation in safety and quality,” I was told by Ready Pac. I knew when I set out to understand “triple-washed” that I was scratching at the surface of ad copy, but I didn’t expect to find more copy underneath.

Ben Chapman, a food safety specialist and researcher at North Carolina State University, explained that triple washing is at least partially an aesthetic preparation. Triple washing is “not just a food safety step,” he said. “It’s a quality step as well.” The lettuce and other greens that go into our salads are grown in sprawling fields full of soil, rocks, sand, and dust. Because greens are eaten raw, any of these elements could potentially make it onto a plate. The triple-wash process greatly reduces the chance of this happening, removing “dirt, debris, anything you might find associated with the environment when you’re harvesting lettuce,” Chapman informs me. So one of the reasons salad producers love to tout the triple-washed process is that it really does help ensure the purity of greens.

But that doesn’t mean greens that have been cleaned of debris are necessarily free of dangerous microbes. Where the triple-washed label becomes dicey is at the level beyond visual perception. Triple-washed greens aren’t necessarily washed with water—in fact, they’re generally washed with sanitizers and other compounds that are intended to reduce pathogens, according to the food safety literature. But Chapman says these substances only tend to eliminate 90 to 99 percent of the microbes. “Only” may seem like a strange word choice for such a drastic decrease, but in microbiology, effectiveness is measured in log reductions, which are tenfold, meaning that each log reduction decreases bacteria to 10 percent of their initial number. A 90- to 99-percent decrease is only a one- to two-log reduction. Because pathogens can exist in superabundance, on a microbial level, a one- to two-log reduction means that there are still enough remaining pathogens to cause and spread illness.

And even a fourth or fifth wash would not reliably drive that number down, because some pathogens ensconce themselves inside the grooves of leaves like hermit crabs in shells, finding microscopic coves that are unreachable by liquids. Citing a 2007 paper published in Food Protection Trends, Chapman informs me that washing at home actually increases the risk of contamination because surfaces at home are likely crawling with germs. “I can’t do any better with the tools I have at my home than what the processor did. There’s no net risk reduction potential for me to wash. I am literally not doing anything by washing it at home,” he` dryly reports. The only way to amp up that log reduction would be to apply heat, which will produce a supersafe five- to seven-log reduction but also ruin your salad.

So triple washing is a tortured compromise with an inconvenient reality: Salad greens aren’t particularly conducive to consumer safety. From its structural ability to harbor pathogens, to its inability to withstand heat, to its wide surface area, to the fact that it is processed in large volumes (increasing the risk of cross-contamination), commercial lettuce is as outbreak-ready as a 14th-century marmot.

What prevents frequent outbreaks (or rather what can prevent outbreaks) is the system of practices that begin long before the lettuce is washed thrice. There’s a sprawling matrix of voluntary audits, mandated inspections, legislation, certifications, research, services, and training available to ensure that salad is safe before it reaches a consumer or a wash basin. The practices that this matrix targets vary depending on the size of the farm and even the species of greens, but the general questions are straightforward. Are crops segregated from animal pins? Are compromised crops being discarded? Are workers wearing gloves? Are storage facilities regularly cleaned? Are wash waters coming from a safe source? These questions may seem basic, but asking them and acting on them can be the difference between life and death.

Although this matrix is not fail-safe, Chapman insists, it does have the potential to prevent outbreaks, but only when buyers (retailers and consumers alike) look at the practices underlying passed inspections and growers actually apply those practices on days other than inspection day.

Don’t eat poop, and if you do, cook it: Manure application research aims to improve food safety

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New field research out of Clarkson University in upstate New York is attempting to answer how likely microbes can travel from manure application sites to downwind produce.

lettuce.skull.noroShane Rogers, an associate professor of civil and environmental engineering, led a research team that looked into the issue. They measured how far common bacteria, including Salmonella and E. coli, are likely to travel downwind from manure application sites. They hoped to better understand how fresh produce might be contaminated by nearby animal agriculture practices.

“Our goal was to provide a logical framework to study this pathway,” Rogers said. This helped them make science-based recommendations for setback distances that protect human health.

The team used field data to understand how these bacteria travel from manure application sites to produce. The research lasted three years. They took samples at several distances from manure application sites and measured the presence of illness-causing bacteria.

The researchers used computer models to expand their understanding. “It is not possible to obtain measurements for every possible set of circumstances that may exist,” Rogers said. “The models allow us to predict produce contamination over a larger range of probable conditions than our raw measurements would provide.” These include the type of manure, the terrain of the farm, and weather conditions at the time the manure is applied.

The team also evaluated the risk of illness. This gave the team a better understanding of how likely someone is to get sick from produce when a certain amount of bacteria is present.

Combining all that data, the team found that produce fields should be set back from areas of manure application by at least 160 meters. That distance should help lower the risk of foodborne illness to acceptable levels (1 in 10,000).

Rogers emphasized that the advice is for a minimum setback. “(160 meteårs is) the minimum distance that produce growers should maintain between manure application activities and produce growing areas,” Rogers said. Additional distance and delay between manure application and harvest would provide further protection.

 

Going public (not so much): Dole inspections show recalls, but no contamination in Ohio facility

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If Dole can’t answer basic questions about the safety of its packaged leafy greens, why should consumers buy the stuff, let alone feel confident?

160122-dole-salad-mn-1530_8b681a6748a4253c3ec1c087b4cd8b0d.nbcnews-fp-1200-800Dole salad products had been recalled in recent years due to concerns about salmonella and listeria before the recent outbreak that shuttered the Springfield facility in January, federal inspection documents show.

The Springfield News-Sun reviewed U.S. Food and Drug Administration records dating back to 2011 obtained through a Freedom of Information Act request.

Those documents show the Springfield plant recalled products a handful of times after traces of listeria and salmonella were found in pre-packaged salad mixes produced there. However samples collected during subsequent inspections didn’t find evidence of contamination at the plant.

A recent lawsuit filed by a Warren County woman also cited at least eight prior outbreaks or recalls company-wide stretching back to 2006.

Dole voluntarily closed the Springfield site in January. It’s not clear whether the site has reopened, in part because company leaders have declined to comment multiple times, but the parking lots is often full of cars.

Products packaged at the facility in the current outbreak were linked to at least 19 hospitalizations in the U.S. in nine states, including one death in Michigan.

In Canada, the outbreak was linked to 14 illnesses in five provinces. Three people in Canada died, however it hasn’t been determined if listeria contributed to those deaths.

listeria4A food safety expert said it’s not uncommon for a food processing facility to remain shuttered for weeks or even months after a significant outbreak.

“This is pretty normal and falls within the expected range of remediation efforts on the part of the organization,” said Naila Khalil, an associate professor in the Center of Global Health at Wright State University.

The Springfield News-Sun reviewed dozens of pages of FDA inspection reports obtained through a public records request.

Those documents show FDA inspectors visited a handful of times since 2011 after samples collected by various agencies contained pathogens like listeria, E. coli and salmonella.

The records also show subsequent samples collected at the Springfield facility didn’t test positive for those pathogens.

The FDA inspected the Springfield site in March 2014 after Canadian public health authorities detected a sample of listeria in a pre-packaged salad blend processed here. Dole voluntarily recalled the product.

In that case, the FDA issued a report to the company for failure to maintain floors and walls in good repair and failure to provide adequate screening or other protection against pests. Additional observations included food residue found on multiple surfaces, water leaks and ice melt dripping onto the floor of the finished product warehouse from a container of iced broccoli.

Specific concerns listed in the report include a cutting board found with deep grooves that couldn’t easily be cleaned, ruts in the floor containing standing water and peeling paint and rust.

Company officials were cooperative and pledged to address those concerns, the report says.

The documents also provide a glimpse into Dole’s sampling and prevention procedures.

The firm collects environmental, water, raw material and finished product sampling, the FDA documents show. The 2014 inspection showed the company’s goal is 50 samples per week, chosen from a list of pre-designated locations on a rotating basis.

In cases in which a pathogen is detected, the area is cleaned and sanitized, followed by additional swabs in a pattern around where the original sample was taken and repeated until no additional traces are found.

Why wouldn’t Dole just make such data public and quell whispers of conspiracy?

 

Jersey, this is a bad idea: Green anole lizard found in salad greens from store becomes class mascot; science teacher says it proves organic is safe

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I’ll leave this to others to comment (and thanks for the contributor who sent it in):

salm.lizard.jan.16Sally Mabon and her kindergartener, Faye, found an unexpected surprise last week when they unwrapped a bundle of tatsoi greens: a 3-inch lizard.

It was cold and lifeless after having survived in the refrigerator for days, but is now thriving after some warmth and moisture.

The following day, Faye brought the critter to Riverside Elementary School, where it has become a mascot of sorts for teacher Mark Eastburn’s science lab.

“Interesting things can happen when you’re working as a science teacher,” he said. “We set up a little cage for it. It really came back amazingly well.”

While some of his fellow teachers were disgusted to hear that a lizard might be lurking in their salad greens, Eastburn said the lizard can teach them a couple of lessons: that organic food is safe for even the smallest of creatures, and that during the cold months, fresh fruits and vegetables need to come from warmer regions.

He said green anole lizards live in the southeastern United States, from Texas to North Carolina.

The lizard, nicknamed “Green Fruit Loop” by the kindergarteners, traveled from Florida.

“It probably has some moderate adaptation to the cold which is why it made it through,” Eastburn said.

Mabon bought the tatsoi from Whole Earth Center, a Princeton natural foods store whose produce is 100 percent organic (marketed that way).

Mike Atkinson, the store’s produce manager, said the lizard’s survival is a testament to organic food, which is generally grown without synthetic pesticides or fertilizers.

“I don’t think the lizard would’ve made it in a conventional, non-organic box,” he said. “It might normally surprise or freak out conventional shoppers, but the majority of organic shoppers realize that produce is grown on a farm and there’s lots of bugs and animals that live on a farm too. It shouldn’t be a surprise that one here and there makes it to the produce shelf.”

Eastburn has been teaching about DNA so he said it makes sense that the green anole lizard — the first reptile to have its genome sequenced — has now found a new home in the lab.

“It’s a really fitting mascot for our science lab,” he said.

LGMA silent on Listeria outbreak

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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 in 2006 that killed four and sickened 200 – blowing themselves about how great they are, and how their products are so safe.

spongebob.oil.colbert.may3.10If you want that kind of PR, then you have to be 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.

LGMA says essentially that epidemiology doesn’t matter, and product must be shown to have the same outbreak strain as someone who is sick.

lettuce.skull.e.coli.O145That happened with spinach in 2006, and it has happened again with Listeria in 2016 – 2 dead, 19 sick, Canada and the U.S., all linked to Dole pre-packed salads.

Sure, it was probably the plant in Ohio that processed the stuff that was the source of the Listeria (and when I think of Ohio, I think salad).

But where’s the tweet, LGMA?

 

Lettuce is overrated: Bad bugs in leafy greens

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Microbial pathogen infiltration in fresh leafy greens is a significant food safety risk factor.

lettuce.tomato.skullIn various postharvest operations, vacuum cooling is a critical process for maintaining the quality of fresh produce. The overall goal of this study was to evaluate the risk of vacuum cooling-induced infiltration of Escherichia coliO157:H7 into lettuce using multiphoton microscopy.

Multiphoton imaging was chosen as the method to locate E. coli O157:H7 within an intact lettuce leaf due to its high spatial resolution, low background fluorescence, and near-infrared (NIR) excitation source compared to those of conventional confocal microscopy. The variables vacuum cooling, surface moisture, and leaf side were evaluated in a three-way factorial study with E. coli O157:H7 on lettuce. A total of 188 image stacks were collected. The images were analyzed for E. coli O157:H7 association with stomata and E. coli O157:H7 infiltration. The quantitative imaging data were statistically analyzed using analysis of variance (ANOVA).

The results indicate that the low-moisture condition led to an increased risk of microbial association with stomata (P < 0.05). Additionally, the interaction between vacuum cooling levels and moisture levels led to an increased risk of infiltration (P < 0.05). This study also demonstrates the potential of multiphoton imaging for improving sensitivity and resolution of imaging-based measurements of microbial interactions with intact leaf structures, including infiltration.

 Influence of vacuum cooling on Escherichia coli O157:H7 infiltration infresh leafy greens via a multiphoton-imaging approach

Appl. Environ. Microbiol. January 2016 82:106-115; Accepted manuscript posted online 16 October 2015, doi:10.1128/AEM.02327-15

Erica Vonasek and Nitin Nitin

http://aem.asm.org/content/82/1/106.abstract?etoc

39 sick: UK E. coli O157 outbreak linked to leafy greens

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In early August 2015 a number of cases of Escherichia coli O157 phage type 8 verotoxin type 2a (MLVA profile 17-9-6-13-8-4-5-5 or a single locus variant thereof) were found to be genetically clustered by whole genome sequencing (WGS) and to share the same SNP address.

lettuce.skull.e.coli.O145As of 3 September, the cluster comprises 38 confirmed cases, with one additional probable case and four possible cases for which WGS results are pending. Onset dates for confirmed and probable cases range from 29 July to 12 August 2015. Cases are widely distributed across England, with one case in Wales but none identified in Scotland to date. In England, the majority of confirmed cases (seven each) have been reported from Anglia and Cheshire and Merseyside, with 14 additional Health Protection Teams across the country also affected and reporting between one and three cases each. Most cases are female aged 18 to 73 years.

Analysis of enhanced questionnaires has shown that 33/38 confirmed members of the cluster had exposure to pre-packed salad and that 19 of these had purchased their pre-packed salad at the same supermarket chain. A focused survey carried out with 24 of the confirmed cases indicated that the most common exposures were to two salad products from one supermarket chain which share one ingredient. Trace-back has been initiated and one packer/distributor has been identified which is supplied by three farms. Samples are being collected from the supermarket chain outlets visited by cases, the distributor/packer and from the supply farms.

Investigations to determine the exact source and cause of contamination are on-going.

Burying the outbreak announcement in a monthly report and not going public about the source is a public health fail.