When I was attempting a Masters degree (I never finished after almost three years, became a newspaper editor, then went back and got a PhD in Food Science; thanks Mansel for taking me on) looking at susceptible and resistant strains of tomato plants to Verticillium wilt, I had to inoculate these plants and walk up to the lab at all hours of the day and night to nurture and harvest the plants at prescribed times and look at their cells under a microscope – sometimes even electronic – and see what the fungus was doing.
That was 1985.
There have been improvements in technology.
The effects of using contaminated seed and water on the persistence and internalization of Salmonella Newport in organic spinach cultivars- Lazio, Space, Emilia and Waitiki were studied.
Seeds were contaminated by either immersing in a suspension of Salmonella and then sprouted or were sprouted in Salmonella contaminated water in the dark at 25 °C. After 5 days, germinated sprouts were analyzed for S. Newport population and internalization. Germinated sprouts were potted in soil and grown in a plant incubator for 4 weeks. Leaves, stems and roots were sampled for Salmonella population by plating on CHROMagar™. Plants surface-sterilized with chlorine were analyzed for internalized pathogen. Potting soil and water runoff were sampled for Salmonella after 4 weeks of plant growth.
Contaminated seeds and irrigation water had S. Newport populations of 7.64±0.43 log CFU/g and 7.12±0.04 log CFU/ml, respectively. Sprouts germinated using contaminated water or seeds had S. Newport populations of 8.09±0.04 and 8.08±0.03 log CFU/g, respectively and had a Salmonella population that was significantly higher than other spinach tissues (P<0.05). Populations of S. Newport in leaves, stem and roots of spinach plants were as follows: contaminated seed- 2.82±1.69, 1.69±0.86, and 4.41±0.62 log CFU/ml; contaminated water- 3.56±0.90, 3.04±0.31, and 4.03±0.42 log CFU/ml of macerated tissue suspension, respectively. Internalization was observed in plants developing from contaminated seeds and in sprouts germinated using contaminated water. S. Newport populations of 2.82±0.70 log CFU/g and 1.76±0.46 log CFU/ml were recovered from soil and water runoff, respectively.
The results indicate that contamination of spinach during germination can result in persistence, internalization and environmental reintroduction of Salmonella.
Contamination of spinach at germination: A route to persistence and environmental reintroduction by salmonella, 02 August 2020
Something is probably lost in translation. But as reported by Repubblica Milano and translated in ProMed, a batch of Bonduelle brand frozen spinach was removed from the market.
The decision of the company, which produces the food in question at a Spanish plant in Navarre, came after a warning from the Ministry of Health. “The product should not be consumed — reads in the recall — due to a suspected presence of mandrake leaves.”
The withdrawal concerns production batch 15986504-7222 45M63 08:29 whose 750g bags have an expiration date of August 2019.
On 30 Sep 2017, an entire family was admitted to the Fatebenefratelli hospital in Milan after eating a pack of frozen spinach bought at the supermarket. A 60-year-old man, a 55-year-old woman, and their children, 18 and 16 years old, ended up at the first aid unit because they showed mental confusion and amnesia of various degrees of severity.
The AST [local health authority] analyses have determined that the clinical picture is compatible with contamination of the original product with mandrake, a grass that can invade fields of edible vegetable crops. The leaves of mandrake, thought to be magical in antiquity, are actually poisonous.
The company issued a clarification in the evening. “There is no information — the statement reads — that permits the attribution of mandrake leaf contamination of our products.” Bonduelle — adds the note — is issuing the recall of some of the product ‘Spinaci Millefoglie Bonduelle’ as a precautionary measure.”
In sentencing me to jail in 1982, the judge said I had a memory of convenience.
I had said I had a memory of not much.
Spinach and lettuce growers seem to have a memory of not much, given the produce industry’s revisions to the 2006 E. coli O157:H7 outbreak in spinach that killed four and sickened 200.
In October, 1996, a 16-month-old Denver girl drank Smoothie juice manufactured by Odwalla Inc. of Half Moon Bay, California. She died several weeks later; 64 others became ill in several western U.S. states and British Columbia after drinking the same juices, which contained unpasteurized apple cider — and E. coli O157:H7. Investigators believed that some of the apples used to make the cider might have been insufficiently washed after falling to the ground and coming into contact with deer feces.
In the decade between these two watershed outbreaks, almost 500 outbreaks of foodborne illness involving fresh produce were documented, publicized and led to some changes within the industry, yet what author Malcolm Gladwell would call a tipping point — “a point at which a slow gradual change becomes irreversible and then proceeds with gathering pace” (http://en.wikipedia.org/wiki/Tipping_Point) — in public awareness about produce-associated risks did not happen until the spinach E. coli O157:H7 outbreak in the fall of 2006. At what point did sufficient evidence exist to compel the fresh produce 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 1996, following extensive public and political discussions about microbial food safety in meat, the focus shifted to fresh fruits and vegetables, following an outbreak of Cyclospora cayetanesis ultimately linked to Guatemalan raspberries that sickened 1,465 in 21 U.S. states and two Canadian provinces (U.S. Centers for Disease Control and Prevention, 1997), and subsequently Odwalla. That same year, Beuchat (1996) published a review on pathogenic microorganisms in fresh fruits and vegetables and identified numerous pathways of contamination.
E. coli O157:H7
E. coli O157:H7
E. coli O157:H7
E. coli O153:H48
E. coli O153:H47
E. coli O157:H7
E. coli O153:H46
E. coli O157:H10
E. coli O153:H49
Table 1. Outbreaks of foodborne illness related to leafy greens, 1992-1996.
By 1997, researchers at CDC were stating that pathogens could contaminate at any point along the fresh produce food chain — at the farm, processing plant, transportation vehicle, retail store or foodservice operation and the home — and that by understanding where potential problems existed, it was possible to develop strategies to reduce risks of contamination. Researchers also reported that the use of pathogen-free water for washing would minimize risk of contamination.
E. coli O157:H9
E. coli O111:H8
E. coli O157:H11
E. coli O157:H7
E. coli O157:H7
E. coli O157:H7
Table 2. 1999 U.S. outbreaks of STEC linked to leafy greens
Yet it would take a decade and some 29 leafy green-related outbreaks before spinach in 2006 became a tipping point.
E. coli O157:H7
E. coli O157:H7
E. coli O157:H8
E. coli O157:H7
E. coli O157:H7
Table 3: Leafy green outbreaks of STEC, 2000 — 2002.
What was absent in this decade of outbreaks, letters from regulators, plans from industry associations and media accounts, was verification that farmers and others in the farm-to-fork food safety system were seriously internalizing the messages about risk, the numbers of sick people, and translating such information into front-line food safety behavioral change.
E. coli O157:H7
E. coli O157:H7
E. coli O157:H7
E. coli O157:H7
Table 4: Leafy green STEC outbreaks, 2003 — 2005.
So why was spinach in 2006 the tipping point?
It shouldn’t have been.
But it lets industry apologists say, how the hell could we known?
Tom Karst of The Packer reports the crisis of confidence in the status quo of produce safety practices arrived with a thud a little more than 10 years ago.
Beginning Sept. 14 and continuing until Sept. 20, 2006, the U.S. Food and Drug Administration issued daily news releases that flatly advised consumers “not to eat fresh spinach or fresh spinach-containing products until further notice.”
The agency had never before issued such a broad warning about a commodity, said Robert Brackett, who in 2006 was director of FDA’s Center for Food Safety and Applied Nutritions. Brackett is now vice president and director of the Institute for Food Safety and Health at the Illinois Institute of Technology,
“In this particular case all we knew (was) that it was bagged leafy spinach, but we had no idea whose it was or where it was coming from,” he said in December of this year.
“It was a very scary couple of days because we had all of these serious cases of hemolytic-uremic syndrome popping up and people getting sick, and it was so widespread across the country.”
The Centers for Disease Control and Prevention reported about half of those who were ill were hospitalized during the 2006 spinach E. coli outbreak.
“It was shocking how little confidence that FDA and consumers had in the produce industry at that moment,” said David Gombas, retired senior vice president of food safety and technology for the Washington, D.C.-based United Fresh Produce Association.
Given the history of outbreaks, the only thing shocking was that the industry continued to expect blind faith.
“For FDA to say ‘Don’t eat any spinach,’ they blamed an entire commodity, and it became very clear to the produce industry at that moment they had to do something to restore public confidence and FDA confidence in the safety of fresh produce,” Gombas said Nov. 30.
“One of the things that was very different and had the greatest impact was the consumer advisory against spinach — period — regardless of where it came from,” said Trevor Suslow, extension research specialist and director of the University of California-Davis Postharvest Technology Center.
The stark warning — immediately followed by steeply falling retail spinach sales — was issued in the midst of a multistate E. coli foodborne illness outbreak eventually linked to Dole brand baby spinach.
The product was processed, packed and shipped by Natural Selection Foods of San Juan Bautista, Calif., which markets the Earthbound Farm brand.
U.S. Department of Agriculture data shows that California’s spinach shipments plummeted from 258,774 cartons in August 2006 to 138,278 cartons in September, a drop of nearly 50%.
Shipping point prices for spinach on the California coast dropped from $8.45-10.45 per carton on Sept. 14 — the day that FDA first issued its advice to avoid for consumers to avoid spinach — to $4.85-6.15 per carton on Sept. 15.
No market was reported by the USDA for the rest of September because supplies were insufficient to quote.
The final update on the 2006 spinach outbreak was published by the CDC in October. By March 2007, the FDA issued its own final report about its investigation on the cause of the outbreak.
The CDC said in October 2006 that 199 persons infected with the outbreak strain of E. coli O157:H7 were reported to CDC from 26 states. Later, the tally of those sickened was raised to 205.
Gombas said the FDA warning in mid-September caused leafy green sales to crash, not fully recovering for nearly a decade.
“There were outbreaks before that, but none of them were as devastating to industry or public confidence as that one.”
The FDA and the California Department of Public Health issued a 51-page report on the extensive investigation into the causes of an E. coli O157:H7 outbreak associated with the contaminated Dole brand baby spinach.
The report said investigators identified the environmental risk factors and the areas that were most likely involved in the outbreak. However, they were unable to definitely determine the source of the contamination.
The investigation explored the source of the spinach in 13 bags containing E. coli O157:H7 isolates that had been collected nationwide from sick customers, according to a summary of the report.
Using the product codes on the bags, and employing DNA fingerprinting on the bacteria from the bags, the investigators were able to match environmental samples of E. coli O157:H7 from one field to the strain that had caused the outbreak, according to the report.
The report said E. coli O157:H7 isolates located on the Paicines Ranch in San Benito had a (pulsed-field gel electrophoresis) pattern indistinguishable from the outbreak strain. The report said the pattern was identified in river water, cattle feces and wild pig feces on the Paicines Ranch, the closest of which was just under one mile from the spinach field.
According to investigators, the sources of the potential environmental risk factors for E.coli contamination at or near the field included the presence of wild pigs and the proximity of irrigation wells and waterways exposed to feces from cattle and wildlife.
From 1995 to 2006, researchers had linked nine outbreaks of E. coli O157:H7 infections to, or near, the Salinas Valley region. But the 2006 spinach outbreak was different.
There were guidelines for growers in 2006, but not a way to make sure growers were following them, said Joe Pezzini, CEO of Ocean Mist Farms, Castroville, Calif.
Through the nanotubes, which are one ten-thousandth the diameter of a human hair, the plant can detect the chemicals through the air and groundwater.
Researchers also applied a solution of nanoparticles to the underside of the leaves and placed sensors into a leaf layer (known as the mesophyll) where most photosynthesis takes place.
To read the signals the plants give off, researchers shine a laser on the leaves which prompts the carbon nanotubes to emit a near-infrared fluorescent light.
That light is picked up by using an infrared camera connected to a Raspberry Pi, a credit-card-sized computer, similar to the computer used in a smartphone.
The Raspberry Pi then sends an email to the phone, alerting the owner to the presence and size of an explosive.
By engineering these plants to act as chemical sensors, scientists can perform monitoring tasks in public spaces and identify potential terrorism threats at mass-attended events, said Michael Strano, professor of chemical engineering at MIT.
“They could also be used on the periphery of a chemical plant and even fracking sites.”
Plants are ideal for this purpose as they have extensive root networks to monitor groundwater, are self-repairing, and are naturally adaptive to where they exist.
“If you think of taking your iPhone or a piece of electronics outside and having it adapt to the temperature changes, it’s actually an engineering challenge,” said Professor Strano.
“We look at the plant for a great starting point for technology.
“It’s amazing it hasn’t been explored for this purpose.”
The researchers can pick up the warning signal from about one metre away, but are working to increase that distance.
As well as spinach, researchers used rocket and watercress as chemical sensors, choosing to use plants that were commonly available.
“We wanted to show that these techniques work with plants found in the wild or a nursery, rather than using genetically-engineered plants,” Professor Strano said.
By using plants that already exist in the wild, the need to create new organisms which may have problems surviving is eliminated.
Purpose: The objective of this study was to evaluate the comprehensiveness of a metagenomics approach for detection and strain level identification of STEC on bagged spinach using pathogenic STEC strains of a variety of serotypes and Shiga toxin subtypes.
Methods: Bagged spinach was spiked with one of 12 STEC strains at a level of 0.1 CFU/g spinach and processed according to the U.S. FDA BAM protocol. Sequencing data generated from each sample was used to determine molecular serotype and STEC-specific virulence genes by BLAST analysis, identify the microbial communities present in the enriched sample using a discriminative k-mer method, and perform E. coli core gene SNP analysis on de novo assemblies of the metagenomic sequencing data.
Results: Bacterial community analysis determined that E. coli was a major component of the population in most samples, but molecular serotyping using the metagenomic data revealed the presence of indigenous E. coli in some samples. Despite the presence of additional E. coli strains, the serotype and virulence genes of the spiked STEC, including correct Shiga toxin subtype, were detected in 92% of the samples. E. coli core gene SNP analysis of the metagenomic sequencing data correctly placed the spiked STEC in a phylogeny of related strains in cases where the indigenous E. coli did not predominate.
Significance: Utilizing a shotgun metagenomics approach to characterize STEC contaminating bagged spinach may expedite the time necessary to ascertain the risk level to public health and response time during outbreaks.
Evaluation of the use of shotgun metagenomics sequencing for detection and strain level discrimination of Shiga toxin producing Escherichia coli contamination on fresh bagged spinach
Susan Leonard, U.S. Food and Drug Administration, Laurel, MD, Mark Mammel, U.S. Food and Drug Administration, Laurel, MD, David Lacher, U.S. Food and Drug Administration, Laurel, MD, Christopher Elkins, U.S. Food and Drug Administration, Laurel, MD
Package size and description: Sold in 150gm and 500gm plastic packs and 3kg cartons.
Distribution: The product is sold in bulk to foodservice and some retail customers nationwide.
Customers are asked to check the batch number and date marking. Affected products should not be consumed. There have been no reports of illness, however if you have consumed any of these products and have any concerns about your health please seek medical advice.
A new study suggests that a molecule found in green, leafy vegetables such as spinach contains bacterium-fighting ingredients that could prove a cure to common cases of food poisoning .
Veg are essential for good human gut health because of the presence of an unusual sulphur-containing sugar molecule.
The molecule , known as sugar sulfoquinovose or SQ, is essential for feeding good gut bacteria, limiting the ability of bad bacteria to colonise the gut by shutting them out of the prime “real estate.”
But now researchers have discovered an enzyme in the foods which are used by good bacteria to feed on these sugar molecules.
The discovery of enzyme YihQ could now be exploited to develop new strains of antibiotics to counteract E.coli and Salmonella.
And it also breaks the food down to turn it into sulphur, which re-enters the atmosphere to be reused by other organisms.
The findings, to be reported Monday, Aug. 10, in the journal Proceedings of the National Academy of Sciences, call into question the effectiveness of removing non-crop vegetation as a way to reduce field contamination of fresh produce by disease-causing pathogens. This practice led to extensive loss of habitat in a region that is globally important for food production and natural resources.
The practice was implemented largely in response to a 2006 outbreak of pathogenic E. coli in packaged spinach that killed three people and sickened hundreds of others in the United States. That outbreak was traced to a farm in California’s Central Coast, a region that supplies more than 70 percent of the country’s salad vegetables. The disease-causing E. coli strain was found throughout the farm environment — including in the feces of nearby cattle and wild pigs — but the cause of the outbreak has never been officially determined.
“Wildlife took much of the blame for that outbreak, even though rates of E. coli in wildlife are generally very low,” said study lead author Daniel Karp, a NatureNet postdoctoral research fellow in UC Berkeley’s Department of Environmental Science, Policy and Management and The Nature Conservancy. “Now, growers are pressured by buyers to implement practices meant to discourage wildlife from approaching fields of produce. This includes clearing bushes, plants and trees that might serve as habitat or food sources for wild animals. Our study found that this practice has not led to the reductions in E. coli and Salmonella that people were hoping for.”
Instead, the study authors noted that the presence of diverse habitats bordering food crops can actually provide a number of agricultural benefits.
“There is strong evidence that natural habitats surrounding crop fields encourage wild bee populations and help the production of pollinated food crops,” said study senior author Claire Kremen, a UC Berkeley professor of environmental science, policy and management. “There have also been studies that suggest that a landscape with diverse plant life can filter out agrichemical runoff and even bacteria. Changing this dynamic shouldn’t be taken lightly.”
The researchers analyzed about 250,000 tests of produce, irrigation waters and rodents conducted by industry and academics from 2007 through 2013. The tests were conducted on samples from 295 farms in the United States, Mexico and Chile, and targeted the presence of pathogenic E. coli, Salmonella and generic strains of E. coli. The researchers combined the test data with a fine-scale land-use map to identify characteristics of the landscape surrounding the agricultural fields.
The researchers found that the removal of riparian or other vegetation did not result in lower detection of pathogens in produce, water or rodents. Overall, the prevalence of pathogenic E. coli in leafy green vegetables had increased since the outbreak, even as growers removed non-crop flora. In fact, the growers who removed the most vegetation experienced the greatest increase in pathogenic E. coli and Salmonella in their vegetables over time.
“Clearing surrounding vegetation is a costly, labor-intensive practice that threatens wildlife habitat,” said Karp. “Since it does not improve food safety, there is no reason to continue this practice.”
The study did find, however, that the likelihood of detecting pathogenic E. coli was greater when fields were within 1.5 kilometers of grazeable land than when they were farther away.
“It is unclear whether it was the cattle or wildlife grazing on those lands that were responsible for the elevated pathogen levels, but there are a number of ways that farming and ranching can co-exist in a diversified system,” said Karp.
Some suggestions include:
Leaving strips of vegetation between the grazed areas and fresh produce areas
Fencing off upstream waterways from cattle to prevent waste from going downstream
Planting crops that are usually cooked before being eaten – such as corn, artichokes and wheat – between fresh produce fields and grazeable lands
After the 2006 E. coli outbreak in spinach, California’s agricultural industry implemented a voluntary certification program called the Leafy Green Products Handler Marketing Agreement. At the federal level, in 2011 President Obama signed the Food Safety Modernization Act, considered one of the most sweeping reforms in farming practices in decades. Both efforts shift the focus to preventing rather than responding to outbreaks.
Notably, neither the federal law nor the state program calls for the removal of wildlife habitat surrounding crops, but private buyers, keen on retaining consumer confidence in their products, may still require growers to take steps that go beyond government regulations.
“The real worry for me is that federal law will be interpreted as the floor rather than the ceiling of what farmers should do,” said Karp. “There is this misguided idea that agricultural fields should be a sanitized, sterilized environment, like a hospital, but nature doesn’t work that way.”
Other co-authors of the study are Sasha Gennet, senior scientist at The Nature Conservancy; Christopher Kilonzo, Melissa Partyka and Edward Atwill at UC Davis; and Nicolas Chaumont at Stanford University.
A farming landscape can be co-managed for both produce safety and nature conservation. Promising practices include: (1) planting low-risk crops between leafy-green vegetables and pathogen sources, such as grazeable lands, (2) buffering farm fields with non-crop vegetation to filter pathogens from runoff (3) fencing upstream waterways from cattle and wildlife (4) attracting livestock away from upstream waterways with water troughs, supplement and feed (5) vaccinating cattle against foodborne pathogens (6) creating secondary treatment wetlands near feedlots and high-intensity grazing operations (7) reducing agro-chemical applications to bolster bacteria that depredate and compete with E. coli (8) exposing compost heaps to high temperatures through regular turning to enhance soil fertility without compromising food safety, and (9) maintaining diverse wildlife communities with fewer competent disease hosts.
Recent Listeriosis outbreaks associated to contaminated leafy vegetables have marked the need for technologies to minimize safety issues in fresh and fresh-cut produce.
US scientists at Texas A&M University have studied the effectiveness of washing treatments as a postharvest practice to minimize the growth of the pathogen and L. innocua on fresh baby spinach leaves under different storage temperatures and to evaluate the feasibility of using L. innocua as a surrogate to the pathogen. The objectives of the study were:
1. to determine the response of L. monocytogenes and L. innocua to different washing treatments with or without chlorine (200 mg/L) at room temperature (∼22°C);
2. to assess the effect of natural microbiota load on growth of both microorganisms at different storage temperatures, from 5 to 36°C;
3. to validate the use of L. innocua as a surrogate of L. monocytogenes for further studies with fresh baby spinach leaves.
Scientists developed predictive models to investigate the effect of simulated storage temperature on the growth patterns of L. monocytogenes and L. innocua.
Results showed that each microorganism had a different significant response to the type of washing treatment at room temperature and the pathogen was harder to remove from the leaves than the L. innocua was.
Although, the natural microflora on fresh baby spinach leaves affected the growth parameters (Maximum grow rate, lag time, maximum population density) for both bacteria, the effect was not significant. Thus, in the specific case of spinach leaves, the study shows that L. innocua may be a suitable surrogate for L. monocytogenes in growth studies.
Growth data for L. monocytogenes and L. innocua on fresh baby spinach leaves at 5–36 °C were modelled using the Baranyi and Ratkowsky (secondary) models which were validated by comparing the root mean square error (RMSEs) and biases between the growth data and model predictions. The secondary models showed good agreement between observed and predicted values.
The validation results show that these models could provide reliable estimates for growth of L. monocytogenes and L. innocua as a function of temperature. These models may be used by processors to evaluate the impact of postharvest practices such as storage and washing on the growth of Listeria in baby spinach leaves evaluated in this study. These models can provide useful input to quantitative risk assessment models.
Basri Omac, Rosana G. Moreira, Alejandro Castillo, Elena Castell-Perez, “Growth of Listeria monocytogenes and Listeria innocua on fresh baby spinach leaves: Effect of storage temperature and natural microflora”, 2015, Postharvest Biology and Technology, Vol. 100, 41–51.
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.
Next 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.
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.”