Aftermath of the Deadly US E coli O157 contaminated Spinach Disaster: Policy Change?

News reports of a deadly spinach food disaster affecting 199 people in the US, where three deaths and 102 hospitalisations occurred were covered in earlier GMO Pundit posts.

This current post is for anyone seriously interested in the policy implications and the serious public health science of E. coli O157 in foods highlighted by this disaster.


To start we link to Dennis T Avery's and Alex Avery's incisive policy comments, then to some authoritative (and conservative) US Agency (CDC/MMWR) announcements and links describing the science of the epidemiological investigation, and then we provide details of some other relevant scientific papers.

(Update: quotes from the final FDA report link the incident to a farm in transition to organic farming operating using "organic" practices.)

But first Dennis T Avery has a say:

Tainted Spinach Raises Questions of Manure on Food Crops

Center for Global Food Issues, September 27, 2006, By Dennis T. Avery

Ten years after one of the country s top food safety experts warned of danger from putting manure on food crops, Americans are still being devastated by manure-born pathogens. It doesn t have to be.

Contaminated raw spinach has just killed at least one person, brought devastating kidney failure to 23, hospitalized more than 75, and sickened more than 150 people across America. The deadly spinach has been traced back to Natural Selections Foods, the largest grower of organic lettuce and spinach in the United States.


Organic rules bar the use of manufactured fertilizer on their crops, so organics use composted manure and other animal wastes on their fields. Animal manure is the ultimate source of the virulent E. coli O157:H7, which contaminated the spinach.

In 1995, the Journal of the American Medical Association quoted Dr. Robert Tauxe, head of foodborne illnesses for the U.S. Centers for Disease Control, telling a medical conference that Organic means a food is grown in animal manure. . . . We got rid of human waste in our food and water, and I think we re going to have better control in the future of manure in our food and water.

The Organic Trade Association responded that organic food was safe because farmers compost their manure. Dr. Tauxe responded that Unfortunately, knowledge of the critical times and temperatures needed to make composted animal manures microbiologically safe is incomplete.

Today, USDA organic rules allow manure to be applied after just 3 days of composting right up to harvest time! Raw manure can be applied until 90 to120 days prior to harvest, under most state-level rules for all farms. But a recent University of Minnesota study found that produce grown with manure aged 6 to 12 months was still 19 times more likely to be contaminated with E. coli than foods grown with manure aged more than a year.

Virtually no farmers age their manure for a year as too much of the vital nitrogen gasses off into the air during that time. Instead, most conventional farmers put their manure only on feed crops such as corn or on pasture. That may be why the Minnesota researchers found organic produce three times more likely to be contaminated with E. coli (7% of samples) than conventional (2%).

Organic activists love to claim that the deadly O157:H7 strain of E. coli is caused by factory farming. Not so. The USDA says it has found O157:H7 in every cattle herd it s tested for it. A Swiss study last year found no significant differences in O157:H7 prevalence between organic and conventional dairy farms. Claims that grain feeding of cattle causes O157:H7 to flourish are also unsupported; various studies have found the opposite.

Washing the food can t fully protect consumers either. Rutgers University has shown that lettuce (and likely spinach) can take up O157:H7 via its roots and harbor the pathogens inside the leaves! In short, there is no practical way to ensure full safety in the food crops fertilized with manure, composted or not.

Is it time to get the manure out of human food crops?

States could require that manure either be used on non-food crops or composted for at least a year. Annual questionnaires could identify the relatively few farms that compost with regular government inspections made.

This will raise howls of protest from the organic movement, which also protested the current weak manure rules. However, it s now clear that using manure on food crops involves a serious public risk especially with leafy produce like lettuce and spinach. The organic movement should want to ensure its customers health as urgently as do public health officials.

Eating no longer needs to be a deadly game of Russian roulette.

Alex Avery made the following points in a Sept 20 Media Advisory:

Spinach E. coli contamination: Media Advisory

Sep 20, 2006

Churchville, VA -- The following is to correct misinformation regarding organic farming practices and food safety risks distributed to national media by organic food interest groups in an effort to deflect scrutiny in the wake of the recent and tragic outbreak of virulent

E. coli that has killed at least one, hospitalized nearly 20, and sickened 114 individuals in 21 states.

Unless otherwise identified, all discussion points can be attributed to the Center for Global Food Issues' director of research and education, Alex Avery.

1. Organic farming practices are not safer and may, in fact, be less safe than non-organic farming practices.

• A University of Minnesota study published in the Journal of Food Protection in 2004 concluded that organic produce was six times more likely to be contaminated with E. coli. Salmonella was found on organic lettuce and organic green peppers, but not on any conventional produce. According to the researchers, the "prevalence of E. coli on certified organic produce" was "almost threefold higher than that on conventional", but because of the comparatively smaller conventional food sample size, this difference could not be considered "statistically significant". Yet of the total of 15 farms that had E. coli-positive samples, 13 were organic and only two were conventional. (Mukherjee, A, et al. J of Food Prot 67(5):894-900, 2004)
• The most frequently contaminated product found in the Minnesota study was organic lettuce, with roughly one quarter of organic lettuce samples contaminated by E. coli. The levels of E. coli on organic lettuce and leafy greens was also higher than found on conventional samples.
• Importantly, the research determined that fruits and vegetables were 19 times more likely to be contaminated with E. coli if the manure was composted 6 to 12 months compared to produce fertilized with manure aged more than one year. Current organic manure handling regulations allow application of manure that has been composted foras little as three days right up to harvest time.-- Some have suggested that manure use is "highly regulated" on organic farms but is not regulated on non-organic farms. This is incorrect. Every state has regulations against the use of raw (uncomposted) manure on crops consumed raw. However, all use of manure and manure-based compost by organic and non-organic farmersneeds to be reexamined in light of the findings in the Minnesota study and applied to all.Fortunately, this is essentially the point of "The Lettuce Safety Initiative" that has now been expanded to include spinach. This is a sound policy reaction to this and other E. coli contamination episodes of the past decade, including a multi-state outbreak from organic lettuce that sickened many in Connecticut and Illinois in June of 1996.

2. None of the organic brands from Natural Selections Foods LLC have been cleared of possible contamination by the FDA.

• While Natural Selections Foods LLC has claimed that "manufacturing codes" from packaging retained by patients are all from non-organic spinach, this is totally inadequate information. The FDA and state authorities have package/UPC codes for a relatively small number of victims identified so far.
• Why was Natural Selections posting reassuring (and conflicting) messages about the apparent safety of its organic products on its website only three days into a growing foodborne-illness outbreak for which no products had been cleared and the source of the contamination had yet to be identified?

3. Is E. coli O157:H7 a by-product of grain-based feeding or other "industrial" farming practices? No.

• Studies have found E. coli O157:H7 in every single cattle herd tested by USDA researchers, including cattle raised on open pastures at low densities in remote areas. Genetic evidence indicates the O157:H7 strain arose thousands of years ago. Studies are conflicting as to whether grain-based feed increases the prevalence and sheddingof O157:H7 strains of E. coli compared to grass feeding. Some have found higher rates with grass and hay feeding, others with grain.

4. This outbreak is due to practices used in organic farming While some outbreaks in the past have been thought to have occurred due to cross contamination during rinsing, current regulations - if followed - have been designed to address this hazard.

• Ironically, the Minnesota research indicates that larger, certified operations are considerably less prone to bacterial contamination than smaller, more independent uncertified operations. E. coli contamination rates were roughly twice as high on un- certified organic farms compared to certified farms.

Contact: Alex Avery, Center for Global Food Issues, 540-337-6354 or cell: 540-255-6378

Action Update from Natural Selection Foods Website
Company advises their belief that the source of contamination was third party growers.

A statement from Charles Sweat, COO, Natural Selection Foods (2 pm, PDT)

SAN JUAN BAUTISTA; CALIF; October 4, 2006: This morning, officials from the Food and Drug Administration (FDA) and the Federal Bureau of Investigation arrived at the San Juan Bautista facilities of Natural Selection Foods. According to federal officials, today’s visit is part of the ongoing investigation that the FDA has been conducting related to the E. coli contamination of spinach. It appears that the focus of this latest stage of the investigation continues to be on the fields where the products are grown by third party growers. As we have from the start, we will cooperate completely with this phase of the investigation.

The documents requested today included those that have been previously provided to both the FDA and the California Department of Health Services in the course of the investigation, as well as additional information that investigators believe will be helpful in their investigation. We will continue to cooperate fully with the investigation and welcome all efforts to trace this problem back to its source.

All tests performed on our processing facilities, both those done by independent scientists and government investigators, have been negative (clean). We continue to believe that the source of the contamination was in the fields from which we buy our spinach. While we have always maintained the highest level of food safety standards, last week we implemented a set of aggressive and unprecedented measures to help assure that no contaminated product, spinach or anything else, will enter our processing operation again. We have begun to set in place a program of rigorous testing and analysis of field operations from the seed through to the harvest. Finally, and most importantly, we are testing every lot of fresh product before it enters our processing stream. If contamination is found, the product will either be refused or destroyed. Essentially, we are raising the bar on food safety for any grower whose product will be washed and packaged in our facility.

We will continue to provide relevant updated information as it becomes available.
We are eager to provide financial assistance for out of pocket expenses to victims of this E. coli outbreak. If you or a member of your family:

* was or is ill with E. coli exposure;
* has been officially linked to this outbreak and is counted among the US Food & Drug Administration’s 183 confirmed cases;
* and has consumed one of the spinach brands named in our recall (see below for the complete list);

please contact us at 888-736-2840.
Natural Selection Foods and Earthbound Farm Launch Unprecedented Food Safety Program

On Thursday, September 28, Charles Sweat, Chief Operating Officer of Natural Selection Foods announced the details of an ambitious and unprecedented program that the company had started to ensure the safety of its products and lead the industry to higher standards. The program has been developed with the assistance of some of the country’s leading food safety experts.

Natural Selection Foods will now require a number of measures be taken by each of the growers that supply our company with the fresh cut produce that we pack. What we are proposing will require the close cooperation and support of our farming partners to raise the food safety bar.

* Natural Selection Foods will work with the growers from seed to harvest, inspecting the seed, irrigation water, soil, soil amendments, plant tissues and wildlife, all of which will be tested, monitored and certified.
* Existing sanitation protocols for farm equipment, packaging supplies and transportation vehicles will be enhanced and monitored.
* Most important is what we are calling the “firewall.” We will be testing all of the freshly harvested greens — spinach and everything else — that are brought to our facility before they enter our production stream. If pathogens are detected, the lot will be discarded. This program is modeled on the program successfully implemented by the beef industry and approved by the International Commission on Microbiological Specifications for Food. This “firewall” will prevent anything like this E. coli-contaminated produce from ever entering our facilities.

Natural Selection Foods’ goal is to do whatever it can to prevent another outbreak like this from occurring and, in working toward that goal, we will continue to do what it has always done, setting high standards and leading the industry in quality and food safety.

Finally, we want to be clear that we do not consider food safety a competitive advantage. We will make everything we learn available to everyone in our industry. These are challenging steps and will be challenging to implement, but they will be well worth the effort if we can prevent another outbreak such as this and restore consumer confidence in spinach and fresh cut produce. We are committed to success in this area.


Commentary Update 2 October from Steve Dittmer
Letter to the Editor – New York Times on Spinach
AFF Sentinel Vol.3 #27-
http://www.agribusinessfreedom.org

Colorado Springs, CO Sept. 30, 2006

Last issue we told you about the error-ridden attack on the beef industry in a New York Times op-ed piece regarding the spinach E. coli 0157:H7 case. Below is a copy of a letter-to-the-editor we also sent to the New York Times. Also below is a link to the text of the offending Times article, in case you had not seen the full article.

Very soon, we will also bring you an update on the latest findings of the state and federal investigation into the case.

New York Times: Platform For Irresponsible Attacks

Dear Editor:

Is it too much to ask for the activists and their chief ally, the New York Times, to wait for the facts of the spinach investigation to be discovered before they fixed the blame (“Leafy Green Sewage,” Nina Planck, Op-Ed, 09/21/06)? And it would be too much to expect accurate facts in explaining what they think the investigators will find.

While activist Planck may be sure that feeding grain to animals is the reason they shed E. coli 0157:H7, the research contradicts her. Alex Avery of the Center for Global Food Issues said USDA researchers have found the bacteria in cattle raised in open pastures at low densities in remote areas, as well as feedlots and dairies.

As additional evidence that modern, advanced grain-fed cattle operations did not hatch this pathogen, Avery notes genetic evidence indicates the 0157:H7 strain arose thousands of years ago.

It is also irresponsible to charge that modern agriculture is carelessly going around contaminating produce fields and groundwater supplies. Advanced manure management and ever increasingly regulated and restricted water quality systems for all feedlots and dairies makes any run off problems rare exceptions to the rule. Cattlemen have spent millions of dollars so that distribution is by plan, not accident. The overwhelming majority of the distribution is on crops not fed to humans.

The Times’ willingness to run such an irresponsible, factually inaccurate piece, plus do it before the facts are in is regrettable. The illnesses and death resulting from whatever cause are tragic and our sympathies are with those people and their families. But they deserve to know the truth, not be led on by activists and the Times without the facts of the case or knowledge of the issues.

While no system is perfect, rest assured that America’s farmers and ranchers are dedicated to providing healthy and safe food for America’s people – their customers and their families’ source of livelihood.

Steve Dittmer
Agribusiness Freedom Foundation
Colorado Springs, CO 80908
719/495-0401



US Government Agencies are reporting the outbreak in detail, and some more recent facts have emerged that relate to earlier comments from CGFI:

Latest CDC Updates here

The most specific and authoritative agency comment is from the FDA

FOR IMMEDIATE RELEASE P06-164
October 6, 2006


Media Inquiries:
FDA Press Office: 301-827-6242
Consumer Inquiries:
888-SAFEFOOD

FDA Statement on Foodborne E. coli O157:H7 Outbreak in Spinach This statement is current as of October 6, 2006

Update

To date, 199 cases of illness due to E. coli O157:H7 infection have been reported to CDC, including 31 cases of Hemolytic Uremic Syndrome (HUS), 102 hospitalizations and three deaths. The first death was an elderly woman in Wisconsin. The second death of a two-year-old in Idaho and the third death of an elderly woman in Nebraska were confirmed by CDC today as posted at http://www.cdc.gov/foodborne/ecolispinach/100606.htm.

States Affected
The 26 affected states and numbers of illnesses in each state are: Arizona (8), California (2), Colorado (1), Connecticut (3), Idaho (7), Illinois (2), Indiana (10), Kentucky (8), Maine (3), Maryland (3), Michigan (4), Minnesota (2), Nebraska (11), Nevada (2), New Mexico (5), New York (11), Ohio (25), Oregon (6), Pennsylvania (10), Tennessee (1), Utah (19), Virginia (2), Washington (3), West Virginia (1), Wisconsin (49), and Wyoming (1). In addition, Canada has one confirmed case.

Status
On October 4, 2006, U.S. Attorney Kevin V. Ryan of the Northern District of California issued a statement on the execution of two search warrants on Growers Express in Salinas, California, and Natural Selection Foods in San Bautista, California, in connection with the outbreak. The statement is available online at http://www.usdoj.gov/usao/can/press/2006/2006_10_04_spinachsearches.press.html.

FDA, the State of California, the Centers for Disease Control and Prevention (CDC) and the United States Department of Agriculture (USDA) continue to investigate the cause of this outbreak. This includes continued inspections and sample collection in facilities, the environment and water, as well as studies of animal management, water use, and the environment.

FDA announced on September 29, 2006 that all spinach implicated in the current outbreak has traced back to Natural Selection Foods LLC of San Juan Bautista, California. This determination is based on epidemiological and laboratory evidence obtained by multiple states and coordinated by CDC. Natural Selection Foods issued a recall of all implicated products on September 15, 2006. Four other companies have issued secondary recalls because they received the recalled product from Natural Selections. See below for a complete list of brand names that are subject of the recalls. Spinach processed by other manufacturers has not been implicated in the outbreak.

Next Steps
There has been a long history of E. coli O157:H7 outbreaks involving leafy greens from the central California region. Spinach processed by other manufacturers has not been implicated in this outbreak, but based on discussions with industry, and given the past E. coli O157:H7 outbreaks, While this plan is under development, FDA and the SFDA and the State of California still expect the industry to develop a comprehensive plan which is designed to minimize the risk of another outbreak due to E. coli O157:H7 in spinach grown in central California.tate of California reiterate previous concerns and advise firms to review their current operations in light of the agency's guidance for minimizing microbial food safety hazards.

FDA and the State of California have previously expressed serious concern with the continuing outbreaks of foodborne illness associated with the consumption of fresh and fresh-cut lettuce and other leafy greens. After discussions with industry, FDA and the State of California, as part of a longer term strategy, now expect industry to develop a plan to minimize the risk of another outbreak due to E. coli O157:H7 in all leafy greens, including lettuce.

The Grower Shipper Association of Central California, the Produce Marketing Association, the United Fresh Produce Association, and the Western Growers Association said, "We are committed to working together as one industry to learn everything we can from this tragedy, and will redouble our efforts to do everything in our power to reduce the potential risk of foodborne illness. As we have in the past, we will work aggressively with the Food and Drug Administration and state regulatory authorities to ensure the industry's growing and processing practices continue to be based on the very best scientific information available, and that we are doing everything possible to provide the nation with safe and healthy produce."

Implementation of these plans will be voluntary, but FDA and the State of California are not excluding the possibility of regulatory requirements in the future. FDA will be holding a public meeting to address the larger issue of food borne illness linked to leafy greens later in the year once the current investigation is complete.

Advice to Retailers, Food Service Operators and Consumers

FDA is still reminding the public that Natural Selection Foods has recalled all spinach products under multiple brand names with a date code of October 1, 2006 or earlier. There have been four other recalls from different companies because they received Natural Selection Foods spinach. See below for a complete list of brand names that are subject of the recalls.

In order to protect consumers, retailers and food service operators should not sell raw spinach or blends that may contain spinach that was processed by Natural Selection Foods and all other brands subject to the recalls.

Consumers are advised that proper storage of fresh produce can affect both quality and safety. To maintain quality of fresh produce, certain perishable fresh fruits and vegetables (like strawberries, lettuce, herbs, and mushrooms) can be best maintained by storing in a clean refrigerator at a temperature of 40° F or below. All produce that is purchased pre-cut or peeled should be refrigerated to maintain both quality and safety.

Many precut, bagged produce items like spinach and lettuce are pre-washed. If so, it will be stated on the packaging. This pre-washed, bagged produce can be used without further washing.

Processed spinach (e.g., frozen and canned spinach) is not implicated in this outbreak.

Laboratory Findings

There are now a total of 13 confirmed product samples that contain the E. coli O157:H7 outbreak strain.

* The Colorado Department of Public Health and Environment has confirmed the presence of the outbreak strain of E. coli O157:H7 in a sample of Dole spinach with a lot code of P227A02, and a "best if used by" date of August 30, 2006.
* The Ohio Department of Health confirmed the isolation of E. coli O157:H7, matching the outbreak strain, from a package of Dole Baby Spinach.
* The Wisconsin Department of Health and Family Services has confirmed that E. coli O157:H7, the same strain as that associated with the outbreak, has been found in 2 bags of Dole Baby Spinach with lot codes of P227A.
* The Nevada Department of Health and Human Services has reported a confirmed finding of E. coli O157:H7 in bagged spinach, with a lot code of P227A03, matching the outbreak strain. The Nevada sample was analyzed by FDA Pacific Regional Lab NW.
* The Pennsylvania Department of Health has confirmed that E. coli O157:H7, the same strain as that associated with the outbreak, has been found in 2 individual bags of Dole spinach purchased in Pennsylvania with a "best if used by" date of August 30, 2006, and a lot code of P227A01.
* The Utah Department of Health (UDOH) and the Salt Lake Valley Health Department (SLVHD) have confirmed that E. coli O157:H7, the same strain as that associated with the outbreak, has been found in a bag of Dole Baby Spinach purchased in Utah, with a lot code of P227A01. Laboratory tests were conducted by the Utah Public Health Laboratory (UPHL).
* The New Mexico Department of Health announced on September 20, 2006, that it had linked a sample from a package of Dole Baby Spinach with the outbreak strain of E. coli O157:H7. DNA fingerprinting tests determined that the strain from the spinach matches the strain from patients in the outbreak. The package of spinach that tested positive was Dole Baby Spinach, with a lot code of P227A03.
* The Illinois Department of Public Health has confirmed that E. coli O157:H7, matching the outbreak strain, has been found in a package of Dole Fresh Spinach with a lot code of P227A02, and a "best if used by" date of August 30.
* The Arizona Department of Health Services reported a confirmed finding of E. coli O157:H7 in Dole bagged spinach, with a lot code of P227A03, and a "best if used by" date of August 30, 2006, matching the outbreak strain.
* The Nebraska Health and Human Services System reported a confirmed finding of E. coli O157:H7 in Dole bagged baby spinach, with a lot code of P227A01, and a “best if used by” date of August 30, 2006, matching the outbreak strain.
* The Utah Department of Health reported a confirmed finding of E. coli O157:H7 in Dole bagged baby spinach, with a lot code of P227A01, matching the outbreak strain.

Product Recalls (6)

To date, 6 firms have initiated recalls:

* Based on recall audits conducted by FDA, the agency recently determined that on September 15, 2006, Kenter Canyon Farms, Inc., of Sun Valley, California initiated a voluntary recall of re-packaged spinach. The recalled spinach was part of the nationwide recall of Natural Selection Foods. The product was packaged in 5 oz. clam shell plastic containers. The products recalled were: Kenter Canyon Farms Baby Spinach, Kenter Canyon Farms Mesclun, and Kenter Canyon Farms Spicy Mix. The recalled products were distributed only in Southern California. The "expiration date" located on the back of the package is September 20, 2006.
* On September 22, 2006, Pacific Coast Fruit Company of Portland, Oregon initiated a voluntary recall of products that may include spinach supplied by Natural Selections Foods. Pacific Coast Fruit Company stopped making all products with spinach supplied from California on September 14, 2006. The recalled products are:
Baby Spring Mix Salad Kit (4.6 lbs), Chef on the Run- Bacon Spinach Salad (9 oz. plus 2 fl. oz. dressing), Chef on the Run - Spring Greens Salad (5 oz. plus 2 fl. oz. dressing), Chef on the Run - Willamette Valley Salad (10 oz. plus 2 fl. oz. dressing), Trader Joe's - Baby Spinach and Greens with Bleu Cheese, Candied Pecans and Cranberries with Raspberry Vinaigrette Dressing (10 oz.), Trader Joe's - Baby Greens and Spinach Salad with Wild Maine Blueberry Dressing (10 oz.), Mediterranean Veggie Blend Kit - 15 lbs, and My Brothers Pizza Spinach and Garlic - 15 oz. and 36 oz.
Most of the salad products can be identified by the labels Trader Joe's, My Brothers Pizza or Chef on the Run and are in clam shell containers. Pizza products are in round cardboard bottoms with a plastic over wrap. All salad products will have a "use by date" on or before Sept 20, 2006. Pizza products will have a "use by date" on or before September 23, 2006. The products were distributed through various retail outlets in Alaska, Oregon, Washington and Idaho. There is no international distribution.
* On September 22, 2006,Triple B Corporation, doing business as S.T. Produce, of Seattle, Washington, initiated a voluntary recall of its fresh spinach salad products with a "use by date" of August 22, 2006 thru September 9, 2006. Spinach used in these products may have been supplied from Natural Selections Foods of California. The recalled products were distributed in Washington, Oregon, Idaho and Montana to retail stores and delis and sold in a hard plastic clamshell container.
The products recalled by S.T. Produce are: NWG Spinach Salad (5 oz.),Spinach Salad, QFC (5 oz.), Charlie's Spinach Salad (5 oz.), Charlie's Tabouli & Goat Cheese Salad (10 oz.), NWG Tabouli & Goat Cheese Salad (10 oz.),Tabouli & Goat Cheese Salad, QFC (10 oz.), T/H Spring Mix Salad (5.5 oz.), T/H Mozzarella Spring Mix Salad (5.5 oz.), T/H Baby Spinach Salad (5.5 oz.), Walnut and Blue Cheese Salad w/ Grilled Chicken Breast (6.5 oz.), Larry's Market Tabouli & Goat Cheese Salad (10 oz.), Charlie's Seasonal Greens Salad (2.5 oz.), Charlie's Seasonal Greens Salad (4 oz.), Charlie's Baby Spinach Salad (6 oz.), Charlie's Baby Spinach Salad (5 oz.) and Caesar Bowtie Noodle Salad Kit with Grilled Chicken Breast (6.9 lbs).
* On September 19, 2006, RLB Food Distributors, L.P., West Caldwell, NJ, initiated a voluntary recall of certain salad products that may contain spinach with an 'Enjoy Thru' date of 9/20/06.
The products recalled by RLB are: Balducci's Mesclun Mix 5 oz., Balducci's Organic Baby Spinach 5 oz., Balducci's Mixed Greens 5 oz., FreshPro Mesclun Mix 5 oz., FreshPro Organic Baby Spinach 5 oz., FreshPro Mixed Greens 5 oz., FreshPro Salad Mix with Italian Dressing 4.75 oz., and FreshPro Salad Mix with Ranch Dressing 5.25 oz.
* On September 17, 2006, River Ranch, of Salinas, California, announced a voluntary recall of packages of spring mix containing spinach. River Ranch obtained bulk spring mix containing spinach from Natural Selections. The following brands are involved: Fresh N' Easy Spring Mix and Hy-Vee Spring mix containing baby spinach, distributed to retailers in Texas, Iowa, New Mexico, Georgia and Ohio. Product was packed in 5 oz. bags and 5 oz. plastic trays. Products that do not contain spinach are not part of this recall.
* On September 15, 2006, Natural Selection Foods, LLC, of San Juan Bautista, California, announced a voluntary recall of all products containing spinach in all brands they pack with "best if used by dates" of August 17, 2006 through October 1, 2006. These products include spinach and any salad with spinach in a blend, both retail and food service products. Products that do not contain spinach are not part of this recall.
Natural Selection Foods, LLC brands include: Natural Selection Foods, Pride of San Juan, Earthbound Farm, Bellissima, Dole, Rave Spinach, Emeril, Sysco, O Organic, Fresh Point, River Ranch, Superior, Nature's Basket, Pro-Mark, Compliments, Trader Joe's, Ready Pac, Jansal Valley, Cheney Brothers, D'Arrigo Brothers Co. of New York, Green Harvest, Mann, Mills Family Farm, Premium Fresh, Snoboy, The Farmer's Market, Tanimura & Antle, President's Choice, Cross Valley, and Riverside Farms. The affected products were also distributed to Canada, Mexico, Taiwan, Hong Kong and Iceland. FDA continues to investigate whether other companies and brands are involved.

Symptoms of E. coli O157:H7 Illness

E. coli O157:H7 causes diarrhea, often with bloody stools. Although most healthy adults can recover completely within a week, some people can develop a form of kidney failure called HUS. HUS is most likely to occur in young children and the elderly. The condition can lead to serious kidney damage and even death.
Lettuce Safety Initiative

The FDA developed the Lettuce Safety Initiative www.cfsan.fda.gov/~dms/lettsafe.html in response to recurring outbreaks of E. coli O157:H7 in lettuce. As a result of this outbreak, the initiative has been expanded to cover spinach. The primary goals of the initiative are to reduce public health risks by focusing on the product, agents and areas of greatest concern and to alert consumers early and respond rapidly in the event of an outbreak. This initiative is based on the 2004 Produce Safety Action Plan, intended to minimize the incidence of food borne illness associated with the consumption of fresh produce.
Additional Information

FDA continues to work closely with the CDC and state and local agencies to determine the cause and scope of the E. coli O157:H7 outbreak in spinach. Please check www.fda.gov for updates.

Additional information regarding safe handling of raw produce and fresh-squeezed fruit and vegetable juices can be found at http://www.cfsan.fda.gov/~dms/prodsafe.html.

For additional general food safety tips, go to www.fightbac.org.

Also good reading is the CDC last announcement on the outbreak:

Link to statement that was announced the last CDC update on O157 outbreak.
Update on Multi-State Outbreak of E. coli O157:H7 Infections From Fresh Spinach, October 6, 2006


MMWR Dispatch Sept 26 2006 gives a big overview:

CDC MMWR Dispatch Sept 26th 2006 Dispatch 55;1-2

Ongoing Multistate Outbreak of Escherichia coli serotype O157:H7 Infections Associated with Consumption of Fresh Spinach --- United States, September 2006

On September 13, 2006, CDC officials were alerted by epidemiologists in Wisconsin and Oregon that fresh spinach was the suspected source of small clusters of Escherichia coli serotype O157:H7 infections in those states. On the same day, New Mexico epidemiologists contacted Wisconsin and Oregon epidemiologists about a cluster of E. coli O157:H7 infections in New Mexico associated with fresh spinach consumption. Wisconsin public health officials had first reported a cluster of E. coli O157:H7 infections to CDC on September 8. On September 12, CDC PulseNet had confirmed that the E. coli O157:H7 strains from infected patients in Wisconsin had matching pulsed-field gel electrophoresis (PFGE) patterns and identified the same pattern in patient isolates from other states. This report describes the joint investigation and outbreak-control measures undertaken by state public health officials, CDC, and the Food and Drug Administration (FDA). This investigation and additional case finding are ongoing.

As of September 26, a total of 183 persons infected with the outbreak strain of E. coli O157:H7 had been reported to CDC from 26 states (Figure 1). Among the ill persons, 95 (52%) were hospitalized, 29 (16%) had hemolytic uremic syndrome (HUS), and one person died. The deaths of two other patients possibly related to this outbreak are under investigation. Eighty-five percent of patients reported illness onset from August 19 to September 5 (Figure 2). Fresh spinach was identified as the source of the outbreak. One hundred twenty-three of 130 patients (95%) reported consuming uncooked fresh spinach during the 10 days before illness onset. In addition, E. coli O157:H7 with a PFGE pattern matching the outbreak strain has been isolated from three open packages of fresh spinach consumed by patients (one from New Mexico, one from Utah, and one from Pennsylvania).

On September 14, FDA advised consumers by press release and press conference to not eat bagged fresh spinach. On September 15, a California company that bags spinach under several brand names announced a voluntary recall of all fresh spinach-containing products. On September 16, FDA expanded its warning and advised consumers to not eat fresh spinach or fresh spinach-containing products. On September 21, FDA informed consumers that only spinach grown in three California counties (Monterey, San Benito, and Santa Clara) was implicated in the outbreak.

A confirmed case is defined as a culture-confirmed E. coli O157:H7 infection in a person residing in the United States, with illness onset from August 1 to the present (or, if date of onset is unknown, E. coli O157:H7 isolated from August 15 to the present) and a PFGE [Pulse-field gel ectrophoresis, a DNA fingerprinting method] pattern identified by the XbaI restriction enzyme that matches the pattern of the outbreak strain. August 1 was selected as the earliest illness onset date in the case definition to ensure that the earliest cases in the outbreak were identified and investigated. However, the first six confirmed cases (with illness onsets during August 2--15) were in persons who did not report fresh spinach consumption during the week before illness onset. The first date that illness onset was reported by a person who recently consumed fresh spinach was August 19.

Infections with this outbreak strain of E. coli O157:H7 (one of 3,520 unique E. coli O157:H7 strains reported to CDC PulseNet since 1996) have been reported sporadically to CDC PulseNet since 2003 (an average of 21 cases per year during 2003--2005). This finding suggests the occasional presence of this strain in the environment and food supply; however, it has not been associated with a recognized outbreak in the past.

The time from illness onset to confirmation that a case of E. coli O157:H7 is part of an outbreak is typically 2--3 weeks, including the time required for an infected person to seek medical care and for health-care providers and public health officials to obtain a culture, transfer the bacterial culture to a public health laboratory, perform PFGE testing, and submit the PFGE pattern into the national database at CDC. In this outbreak, the average time from illness onset to PFGE pattern submission to the national database at CDC has been 15 days; additional information is available at http://www.cdc.gov/foodborne/ecolispinach/reportingtimeline.htm.

Parallel laboratory and epidemiologic investigations were crucial in identifying the source of this outbreak. Timely PFGE testing by state public health laboratories, PFGE pattern submission by states to CDC PulseNet, and analysis of PFGE patterns in the CDC PulseNet national database resulted in rapid detection of the outbreak. Concurrent collection of case exposure information by epidemiologists in affected states and sharing of exposure information among states and CDC led to rapid identification of the suspected food source and public health action. Continued rapid diagnosis, culture, PFGE analysis, and reporting to CDC of E. coli O157:H7 infections are needed to aid this investigation and to detect and investigate E. coli O157:H7 outbreaks in the future.

New information regarding the current E. coli O157:H7 outbreak will be available regularly. The most current information is available online at http://www.cdc.gov/foodborne/ecolispinach; this website contains information updated daily on the number of cases and affected states in addition to general information regarding E. coli O157:H7, resources for clinicians, and activities by CDC and other agencies. The FDA website, at http://www.fda.gov/oc/opacom/hottopics/spinach. html, contains advice for consumers on the current outbreak and food-safety guidelines. CDC's public inquiry line (telephone, 1-800-CDC-INFO) also can provide information on the current outbreak to both the public and health-care workers. Information about the current E. coli O157:H7 outbreak is also available by RSS (Really Simple Syndication); a subscription to the E. coli O157:H7 outbreak RSS information can be obtained at http://www.bt.cdc.gov/rss.

Reported by: State and local health departments. E. coli O157:H7 investigation team, CDC.

Green Leaf Lettuce Recall
For Immediate Release
October 8, 2006

The Nunes Company, Inc.
P.O. Box 673
Salinas, CA 93902

Contact:
Tom Nunes
800-695-5012

The Nunes Company, Inc. Recall of Green Leaf Lettuce Under the
Foxy® Brand for Possible Health Risk

The Nunes Company, Inc. of Salinas, California is initiating a voluntary recall of green leaf lettuce designated by the code 6SL0024 sold October 3, 2006 through October 6, 2006 under the Foxy® brand.

The items recalled by The Nunes Company, Inc. are:

* Green Leaf 24 Count, waxed carton
* Green Leaf 18 Count, cellophane sleeve, returnable carto

The above products may be contaminated with Escherichia coli bacteria (E. coli). Pathogenic E. coli bacteria may cause a diarrheal illness often with bloody stools. Although most healthy adults can recover completely within a week, some people can develop a form of kidney failure called Hemolytic Uremic Syndrome (HUS). HUS is most likely to occur in young children, the elderly, and those with compromised immune systems. The condition can lead to serious kidney damage and even death.

The above products were distributed in Arizona, California, Nevada, Washington, Oregon, Idaho, and Montana, and sold to retail stores, and distributors who may have further sold it to restaurants. The product can be identified as Foxy® green leaf lettuce sold under lot code 6SL0024, and purchased on or after October 3, 2006 through October 6, 2006.

No illnesses have been reported to date.

The recall was initiated when it was discovered that water used to irrigate the product may have been contaminated with E. coli. Subsequent investigation indicated that the problems were caused by temporary use of a secondary water source, initially testing positive for E. coli.

Consumers who have purchased these products are urged to return it to the place of purchase for a full refund. Consumers with questions may contact the Company at 1-800-695-5012.

Via E coli Blog (Marler Clark)
On the state of Monterey County irrigation water
Posted on October 10, 2006 by E. coli Lawyer

Frank Pecarich, a retired soil scientist from Oakland, California, offered his opinion on Monterey County's policies regarding irrigation water for crops in the Salinas Valley in an article for the California Progress Report. In the article he states, "State regulators do not require growers to test irrigation water for contaminants. To us the cause seems apparent and at the same time the circumstance seemingly most glaringly ignored by investigators. For us, the main and continuing problem is the use of tertiary treated effluent to irrigate crops consumed fresh without cooking. In particular and most vulnerable are the soft tissue, leafy green vegetables, lettuce and spinach."

October 13 2006
E. coli strain linked to cattle ranch
ANDREW BRIDGES
Associated Press

AP from WASHINGTON report that the same strain of deadly bacteria that sickened dozens of people nationwide has been found at a cattle ranch in California's Salinas Valley within a mile of spinach fields, investigators said Thursday.

Investigators still can't be sure if the E. coli found in cow manure contaminated the fields, but said the find warrants further investigation...

In this news, investigators still do not know how the feces could have contaminated the spinach implicated in the bacterial outbreak. They also do not know if the ranch used manure from the cattle to fertilize its fields. Nor is there evidence that livestock entered the spinach fields on the ranch. However, wild pigs roamed the property, they said.

"There's lots of wildlife and lots of potential for breakdown in the fencing," Reilly told reporters.

The strain of pathogenic E. coli O157:H7 was found in three cattle fecal samples collected at the ranch, one of four under investigation, the officials said. It matched the strain found in sick patients and in bags of recalled spinach.

Investigators continue to look at agricultural runoff, irrigation water and the hygiene of farm workers as potential sources of the bacteria...
---

Associated Press writers Rachel Konrad in Salinas, Calif., and Lisa Leff in San Francisco contributed to this report.

Wild pigs eyed in tainted spinach probe

ANDREW BRIDGES
Associated Press
Thu, Oct. 26, 2006

AAP are saying in WASHINGTON - Wild pigs may have spread deadly bacteria onto a California spinach field, sparking an outbreak that killed three people and sickened more than 200 others nationwide, investigators said Thursday. They also said the outbreak appears to be over.

According to the item State and federal investigators have narrowed their focus to the ranch, where boar trampled fences that had hemmed in a spinach field.

It says samples taken from a wild pig, as well as from stream water and cattle on the ranch, have tested positive for the same strain of E. coli implicated in the outbreak, Reilly said.

Wild pigs are one "real clear vehicle" that could explain how E. coli spread from cattle on the ranch to the spinach field less than a mile away, Reilly said. The pigs could have tracked the bacteria into the field or spread it through their droppings, he said.

Update 3rd March 2007.

Press reports link a farm in "transition to organic farming" to this food poisoning incident.
See March 3rd GMO Pundit Post on E. coli contamination of spinach.

Now some relevant earlier studies:

Later GMO Pundit Post: Why Cow Poo is Dangerous for a Long Time.


Persistence of enterohemorrhagic Escherichia coli O157:H7 in soil and on leaf lettuce and parsley grown in fields treated with contaminated manure composts or irrigation water.

Islam M, Doyle MP, Phatak SC, Millner P, Jiang X.

Center for Food Safety, University of Georgia, 1109 Experiment Street, Griffin, Georgia 30223-1797, USA.

Outbreaks of enterohemorrhagic Escherichia coli O157:H7 infections associated with lettuce and other leaf crops have occurred with increasing frequency in recent years. Contaminated manure and polluted irrigation water are probable vehicles for the pathogen in many outbreaks. In this study, the occurrence and persistence of E. coli O157:H7 in soil fertilized with contaminated poultry or bovine manure composts or treated with contaminated irrigation water and on lettuce and parsley grown on these soils under natural environmental conditions was determined. Twenty-five plots, each 1.8 by 4.6 m, were used for each crop, with five treatments (one without compost, three with each of the three composts, and one without compost but treated with contaminated water) and five replication plots for each treatment. Three different types of compost, PM-5 (poultry manure compost), 338 (dairy manure compost), and NVIRO-4 (alkaline-stabilized dairy manure compost), and irrigation water were inoculated with an avirulent strain of E. coli O157:H7. Pathogen concentrations were 10(7) CFU/g of compost and 10(5) CFU/ml of water. Contaminated compost was applied to soil in the field as a strip at 4.5 metric tons per hectare on the day before lettuce and parsley seedlings were transplanted in late October 2002.
Contaminated irrigation water was applied only once on the plants as a treatment in five plots for each crop at the rate of 2 liters per plot 3 weeks after the seedlings were transplanted.

E. coli O157:H7 persisted for 154 to 217 days in soils amended with contaminated composts and was detected on lettuce and parsley for up to 77 and 177 days, respectively, after seedlings were planted. Very little difference was observed in E. coli O157:H7 persistence based on compost type alone. E. coli O157:H7 persisted longer (by more than 60 days) in soil covered with parsley plants than in soil from lettuce plots, which were bare after lettuce was harvested.

In all cases, E. coli O157:H7 in soil, regardless of source or crop type, persisted for more than 5 months after application of contaminated compost or irrigation water.

J Food Prot. 2004 Jul;67(7):1365-70.
PMID: 15270487 [PubMed - indexed for MEDLINE]

Prevalence and risk-factor analysis of Shiga toxigenic Escherichia coli in faecal samples of organically and conventionally farmed dairy cattle.

Kuhnert P, Dubosson CR, Roesch M, Homfeld E, Doherr MG, Blum JW.

Institute of Veterinary Bacteriology, Laenggass-Str. 122, Vetsuisse Faculty,
University of Bern, CH-3001 Bern, Switzerland. peter.kuhnert@vbi.unibe.ch

Cattle are a natural reservoir for Shiga toxigenic Escherichia coli (STEC), however, no data are available on the prevalence and their possible association with organic or conventional farming practices. We have therefore studied the prevalence of STEC and specifically O157:H7 in Swiss dairy cattle by collecting faeces from approximately 500 cows from 60 farms with organic production (OP) and 60 farms with integrated (conventional) production (IP). IP farms were matched to OP farms and were comparable in terms of community, agricultural ozone, and number of cows per farm. E. coli were grown overnight in an enrichment medium, followed by DNA isolation and PCR analysis using specific TaqMan assays.
STEC were detected in all farms and O157:H7 were present in 25% of OP farms and 17% of IP farms. STEC were detected in 58% and O157:H7 were evidenced in 4.6% of individual faeces. Multivariate statistical analyses of over 250 parameters revealed several risk-factors for the presence of STEC and O157:H7. Risk-factors were mainly related to the potential of cross-contamination of feeds and cross-infection of cows, and age of the animals. In general, no significant differences between the two farm types concerning prevalence or risk for carrying STEC or O157:H7 were observed. Because the incidence of human disease caused by STEC in Switzerland is low, the risk that people to get infected appears to be small despite a relatively high prevalence in cattle.
Nevertheless, control and prevention practices are indicated to avoid contamination of animal products.

Vet Microbiol. 2005 Aug 10;109(1-2):37-45.

Longitudinal microbiological survey of fresh produce grown by farmers in the upper midwest.

Mukherjee A, Speh D, Jones AT, Buesing KM, Diez-Gonzalez F.

Department of Food Science and Nutrition, University of Minnesota, St. Paul,
Minnesota 55108, USA.

Microbiological analyses of fruits and vegetables produced by farms in Minnesota and Wisconsin were conducted to determine coliform and Escherichia coli counts and the prevalence of E. coli, Salmonella, and E. coli O157:H7. During the 2003 and 2004 harvest seasons, 14 organic farms (certified by accredited organic agencies), 30 semiorganic farms (used organic practices but not certified), and 19 conventional farms were sampled to analyze 2,029 preharvest produce samples (473 organic, 911 semiorganic, and 645 conventional). Produce varieties included mainly lettuces, leafy greens, cabbages, broccoli, peppers, tomatoes, zucchini, summer squash, cucumber, and berries. Semiorganic and organic farms provided the majority of leafy greens and lettuces. Produce samples from the three farm types had average coliform counts of 1.5 to 2.4 log most probable number per g.

Conventional produce had either significantly lower or similar coliform populations compared with the semiorganic and organic produce.

None of the produce samples collected during the 2 years of this study were contaminated with Salmonella or E. coli O157:H7.

E. coli contamination was detected in 8% of the samples, and leafy greens, lettuces, and cabbages had significantly higher E. coli prevalence than did all the other produce types in both years for the three farm types.

The prevalence of E. coli contamination by produce type was not significantly different between the three farm types during these 2 years, with the exception of organic leafy greens, in which E. coli prevalence was one-third that of semiorganic leafy greens in 2003.

These results indicate that the preharvest microbiological quality of produce from the three types of farms was very similar during these two seasons and that produce type appears to be more likely than farm type to influence E. coli contamination.

J Food Prot. 2006 Aug;69(8):1928-36.
PMID: 16924919 [PubMed - indexed for MEDLINE]

Related Links

Preharvest evaluation of coliforms, Escherichia coli, Salmonella, and
Escherichia coli O157:H7 in organic and conventional produce grown by Minnesota
farmers. [J Food Prot. 2004] PMID:15151224

A field study of the microbiological quality of fresh produce. [J Food Prot.
2005] PMID:16161682

Prevalence of Escherichia coli O157:H7 and indicator organisms on the
surface of intact subprimal beef cuts prior to further processing. [J Food Prot.
2006] PMID:16865879

Evaluation of a polymerase chain reaction-based system for detection of
Salmonella enteritidis, Escherichia coli O157:H7, Listeria spp., and Listeria
monocytogenes on fresh fruits and vegetables. [J Food Prot. 2001] PMID:11403127

Shedding of foodborne pathogens by Caenorhabditis elegans in compost-amended
and unamended soil. [Food Microbiol. 2006] PMID:16942998

Preharvest evaluation of coliforms, Escherichia coli, Salmonella, and Escherichia coli O157:H7 in organic and conventional produce grown by Minnesota farmers.

Mukherjee A, Speh D, Dyck E, Diez-Gonzalez F.

Department of Food Science and Nutrition, University of Minnesota, St. Paul,
Minnesota 55108, USA.

Microbiological analyses of fresh fruits and vegetables produced by organic and conventional farmers in Minnesota were conducted to determine the coliform count and the prevalence of Escherichia coli, Salmonella, and E. coli O157:H7. A total of 476 and 129 produce samples were collected from 32 organic and 8 conventional farms, respectively. The samples included tomatoes, leafy greens, lettuce, green peppers, cabbage, cucumbers, broccoli, strawberries, apples, and seven other types of produce. The numbers of fruits and vegetables was influenced by their availability at participating farms and varied from 11 strawberry samples to 108 tomato samples. Among the organic farms, eight were certified by accredited agencies and the rest reported the use of organic practices. All organic farms used aged or composted animal manure as fertilizer.

The average coliform counts in both organic and conventional produce were 2.9 log most probable number per g. The percentages of E. coli-positive samples in conventional and organic produce were 1.6 and 9.7%, respectively. However, the E. coli prevalence in certified organic produce was 4.3%, a level not statistically different from that in conventional samples.

Organic lettuce had the largest prevalence of E. coli (22.4%) compared with other produce types. Organic samples from farms that used manure or compost aged less than 12 months had a prevalence of E. coli 19 times greater than that of farms that used older materials.

Serotype O157:H7 was not detected in any produce samples, but Salmonella was isolated from one organic lettuce and one organic green pepper. These results provide the first microbiological assessment of organic fruits and vegetables at the farm level.

J Food Prot. 2004 May;67(5):894-900.

Persistence of Escherichia coli O157:H7 on lettuce plants following spray irrigation with contaminated water.

Solomon EB, Pang HJ, Matthews KR.

Cook College, Department of Food Science, Rutgers, State University of New Jersey, 65 Dudley Road, New Brunswick, New Jersey 08901-8520, USA.

Irrigation water collected at farms growing crops for human consumption was artificially contaminated with E. coli O157:H7 and used to irrigate lettuce plants. Plants in a growth chamber were spray irrigated either once or intermittently with water contaminated with 10(2) or 10(4) CFU of E. coli O157:H7 per ml and were then sampled over a 30-day period. Only plants exposed to 10(2) CFU/ml on day 1 did not harbor the pathogen at the end of the sampling period. All other treatments resulted in contaminated plants at harvest. Plants irrigated with 10(4) CFU/ml contained high levels (up to 5 log CFU/g) of the pathogen at harvest. The results obtained in this study underscore the assertion that spray irrigation (the application of water directly to plant leaves) is linked to the contamination of crops and suggest that repeated exposure increases the E. coli O157:H7 level on the plant.

J Food Prot. 2003 Dec;66(12):2198-202.
PMID: 14672213 [PubMed - indexed for MEDLINE]

Effect of irrigation method on transmission to and persistence of Escherichia coli O157:H7 on lettuce.

Solomon EB, Potenski CJ, Matthews KR.

Department of Food Science, Cook College, Rutgers, The State University of New Jersey, New Brunswick 08901-8520, USA.

In this study, the transmission of Escherichia coli O157:H7 to lettuce plants through spray and surface irrigation was demonstrated. For all treatments combined, the number of plants testing positive following a single exposure to E. coli O157: H7 through spray irrigation (29 of 32 plants) was larger than the number testing positive following surface irrigation (6 of 32 plants). E. coli O157:H7 persisted on 9 of 11 plants for 20 days following spray irrigation with contaminated water.

Immersion of harvested lettuce heads for 1 min in a 200 ppm chlorine solution did not eliminate all E. coli O157:H7 cells.

The results of this study suggest that regardless of the irrigation method used, crops can become contaminated; therefore, the irrigation of food crops with water of unknown microbial quality should be avoided.

J Food Prot. 2002 Apr;65(4):673-6.
PMID: 11952218 [PubMed - indexed for MEDLINE]

Thermal inactivation of Escherichia coli O157:H7 in cow manure compost.

Jiang X, Morgan J, Doyle MP.

Center for Food Safety, University of Georgia, 1109 Experiment Street, Griffin, Georgia 30223-1797, USA.

Rates of inactivation of a five-strain mixture of green fluorescent protein-labeled Escherichia coli O157:H7 in autoclaved and unautoclaved commercial cow manure compost with a moisture content of ca. 38% were determined at temperatures of 50, 55, 60, 65, and 70 degrees C. Trypticase soy agar with ampicillin was determined to be the best medium for the enumeration of heat-injured and uninjured cells of green fluorescent protein-labeled E. coli O157:H7. The results obtained in this study revealed that in autoclaved compost, E. coli O157:H7 reductions of ca. 4 log CFU/g occurred within 8 h, 3 h, 15 min, 2 min, and less than 1 min at 50, 55, 60, 65, and 70 degrees C, respectively. At 65 and 70 degrees C, considerably less time was required to kill the pathogen in unautoclaved compost than in autoclaved compost. Decimal reduction times (D-values) for autoclaved compost at 50, 55, 60, 65, and 70 degrees C were 137, 50.3, 4.1, 1.8, and 0.93 min, respectively, and D-values for unautoclaved compost at 50, 55, and 60 degrees C were 135, 35.4, and 3.9 min, respectively.

Considerable tailing was observed for inactivation curves, especially at 60, 65, and 70 degrees C.

These results are useful for identifying composting conditions that will reduce the risk of the transmission of E. coli O157:H7 to foods produced in the presence of animal fecal waste.

J Food Prot. 2003 Oct;66(10):1771-7.

PMID: 14572212 [PubMed - indexed for MEDLINE]

Destruction of Escherichia coli O157:H7 and Salmonella enteritidis in cow manure composting.

Lung AJ, Lin CM, Kim JM, Marshall MR, Nordstedt R, Thompson NP, Wei CI.

Food Science and Human Nutrition Department, University of Florida, Gainesville
32611-0720, USA.

Application of cow manure and composted manure in agricultural practice could potentially cause contamination of foodstuffs with pathogenic bacteria such as
Salmonella Enteritidis and Escherichia coli O157:H7. In this study, rifampicin-resistant (RifR) E. coli O157:H7 and Salmonella Enteritidis at a level of 7 log CFU/g of raw compost feed were used to determine the effect of a bench-scale composting system on their survival. RifR E. coli O157:H7 was not detected after 72 h of composting at 45 degrees C, and RifR Salmonella Enteritidis was not detected after 48 h. The use of selective media for enrichment failed to recover in the composting samples held at 45 degrees C for 96 h. However, the pathogens showed no change in bacterial numbers when the composting system was held at room temperature. Thus, properly composted manure can be safely used in food crop production while minimizing the likelihood of microbial contamination.

J Food Prot. 2001 Sep;64(9):1309-14.
PMID: 11563505 [PubMed - indexed for MEDLINE]

Fate of Escherichia coli O157:H7 in manure compost-amended soil and on carrots and onions grown in an environmentally controlled growth chamber.

Islam M, Morgan J, Doyle MP, Jiang X.

Center for Food Safety, University of Georgia, 1109 Experiment Street, Griffin, Georgia 30223-1797, USA.

Studies were done to determine the fate of Escherichia coli O157:H7 in manure compost-amended soil and on carrots and green onions grown in an environmentally
controlled growth chamber. Commercial dairy cattle manure compost was inoculated with a five-strain mixture of green fluorescent protein-labeled E. coli O157:H7
at 10(7) CFU g(-1) and mixed with unsterilized Tifton sandy loam soil at a ratio of 1:5. Baby carrot or green onion seedlings were planted into the manure compost-amended soil in pots, and soil samples surrounding the plant, edible carrot roots and onion bulb samples, and soil immediately beneath the roots were assayed for E. coli O157:H7 in triplicate at weekly intervals for the first 4 weeks, and every 2 weeks for the remainder of the plant growth cycle (up to 3 months). E. coli O157:H7 cell numbers decreased within 64 days by 3 log CFU/g in soil and soil beneath the roots of green onions and by more than 2 log CFU/g on onions.

E. coli O157:H7 survived better during the production of carrots, with a 2.3-log CFU/g reduction in soil and a 1.7-log CFU/g reduction on carrots within 84 days.

These results indicate that the type of plant grown is an important factor influencing the survival of E. coli O157:H7 both on the vegetable and in the soil in which the vegetable is grown.

J Food Prot. 2004 Mar;67(3):574-8.
PMID: 15035376 [PubMed - indexed for MEDLINE]

Survival of pathogenic bacteria in compost with special reference to Escherichia coli.

Gong CM, Koichi I, Shunji I, Takashi S.
Laboratory of Soil Microbiology, Faculty of Agriculture, Saga University, Saga
840-8502, Japan.

Application of compost in agricultural practice could potentially cause contamination of foodstuffs with pathogenic bacteria such as Escherichia coli O157:H7 (E. Coli O157). We investigated pathogenic bacteria in compost collected from the compost facilities, and evaluated the survival of E. coli K12 and O157 in laboratory experiments. Out of 19 compost product samples, coliform bacteria and salmonella were detected in 7 and 3 samples respectively. The number of coliform bacteria was 1.8 x 10(2) to 2.5 x 10(6) CFU/g dw and that of salmonella was 4.2 x 10(1) to 6.0 x 10(3) CFU/g dw. Moreover, coliform bacteria, fecal coliform, E. coli and salmonella were detected during composting at 54 degrees C to 67 degrees C. The results indicated that moisture content was a very important factor to the heat sensitivity of pathogenic bacteria in compost, E.coil in compost of high moisture content was more sensitive than that in compost of low moisture content, cells harvested in logarithmic phase was more sensitive than these in stationary phase, and E. coli K12 was more sensitive than E. coli O157. Based on the D values, the lethal time of E. coli K12 and O157 from l0(8) to 10(0) CFU/g dw were 16.3 and 28.8 min, respectively, at 60 degrees C in compost with 40% moisture content. However, some E. coil cells survived in composting process at 54 degrees C to 67 degrees C. Water potential (low moisture content) and physiological aspects of bacteria (stationary phase) could explain only in part of the prolonged survival of E. coil in compost, and there should be some other factors that are conducive to bacterial survival in compost.

J Environ Sci (China). 2005;17(5):770-4.

Distribution of Escherichia coli O157:H7 within and among cattle operations in pasture-based agricultural areas.

Renter DG, Sargeant JM, Hungerford LL.

Food Animal Health and Management Center, Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA.

OBJECTIVE: To determine the distribution of Escherichia coli O157:H7 in pasture-based cattle production areas.
SAMPLE POPULATION: Two 100-km2 agricultural areas consisting of 207 pasture, 14 beef-confinement, and 3 dairy locations within 24 cattle operations.
PROCEDURE: 13,726 samples from cattle, wildlife, and water sources were obtained during an 11-month period. Escherichia coli O157:H7 was identified by use of culture and polymerase chain reaction assays and characterized by pulsed-field gel electrophoresis (PFGE).
RESULTS: Odds of recovering E coli O157:H7 from feeder-aged cattle were > 4 times the odds for cow-calf or dairy cattle. There was no difference in prevalence for pastured versus confined cattle after controlling for production age group.

Number of samples collected (37 to 4,829), samples that yielded E coli O157:H7 (0 to 53), and PFGE subtypes (0 to 48) for each operation varied and were highly correlated. Although most PFGE subtypes were only detected once, 17 subtypes were detected on more than 1 operation.
Ten of 12 operations at which E coli O157:H7 was detected had at least 1 subtype that also was detected on another operation. We did not detect differences in the probability of having the same subtype for adjacent operations, nonadjacent operations in the same study area, or operations in the other study area.

CONCLUSIONS AND CLINICAL RELEVANCE:
Strategies aimed at controlling E coli O157:H7 and specific subtypes should account for the widespread distribution and higher prevalence in feeder-aged cattle regardless of production environment and the fact that adjacent and distant cattle operations can have similar subtypes.

Am J Vet Res. 2004 Oct;65(10):1367-76.

Probing genomic diversity and evolution of Escherichia coli O157 by single nucleotide polymorphisms.

Zhang W, Qi W, Albert TJ, Motiwala AS, Alland D, Hyytia-Trees EK, Ribot EM, Fields PI, Whittam TS, Swaminathan B.

Foodborne and Diarrheal Diseases Branch, National Center for Infectious
Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia 30333,
USA. zhangw--AT--iit.edu

Infections by Shiga toxin-producing Escherichia coli O157:H7 (STEC O157) are the predominant cause of bloody diarrhea and hemolytic uremic syndrome in the United
States. In silico comparison of the two complete STEC O157 genomes (Sakai and EDL933) revealed a strikingly high level of sequence identity in orthologous protein-coding genes, limiting the use of nucleotide sequences to study the evolution and epidemiology of this bacterial pathogen. To systematically examine single nucleotide polymorphisms (SNPs) at a genome scale, we designed comparative genome sequencing microarrays and analyzed 1199 chromosomal genes (a total of 1,167,948 bp) and 92,721 bp of the large virulence plasmid (pO157) of eleven outbreak-associated STEC O157 strains. We discovered 906 SNPs in 523 chromosomal genes and observed a high level of DNA polymorphisms among the pO157 plasmids. Based on a uniform rate of synonymous substitution for Escherichia coli and Salmonella enterica (4.7x10(-9) per site per year), we estimate that the most recent common ancestor of the contemporary beta-glucuronidase-negative, non-sorbitolfermenting STEC O157 strains existed ca. 40 thousand years ago. The phylogeny of the STEC O157 strains based on the informative synonymous SNPs was compared to the maximum parsimony trees inferred from pulsed-field gel electrophoresis and multilocus variable numbers of tandem repeats analysis. The topological discrepancies indicate that, in contrast to the synonymous mutations, parts of STEC O157 genomes have evolved through different mechanisms with highly variable divergence rates. The SNP loci reported here will provide useful genetic markers for developing high-throughput methods for fine-resolution genotyping of STEC O157. Functional characterization of nucleotide polymorphisms should shed new insights on the evolution,epidemiology, and pathogenesis of STEC O157 and related pathogens.

Genome Res. 2006 Jun;16(6):757-67. Epub 2006 Apr 10.

Complexity of the genomic diversity in enterohemorrhagic Escherichia coli O157 revealed by the combinational use of the O157 Sakai OligoDNA microarray and the Whole Genome PCR scanning.

Ogura Y, Kurokawa K, Ooka T, Tashiro K, Tobe T, Ohnishi M, Nakayama K, Morimoto T, Terajima J, Watanabe H, Kuhara S, Hayashi T.

Division of Bioenvironmental Science, Frontier Science Research Center, University of Miyazaki, Miyazaki, Japan.

Escherichia coli O157, an etiological agent of hemorrhagic colitis and hemolytic uremic syndrome, is one of the leading worldwide public health threats. Genome
sequencing of two O157 strains have revealed that the chromosome is comprised of a 4.1 Mb backbone shared by K-12 and a total of 1.4 Mb O157-specific sequences.
Most of the large O157-specific sequences are prophages and prophage-like elements, which have carried many virulence genes into the O157 genome. This suggests that bacteriophages have played the key roles in the emergence of O157. The Whole Genome PCR Scanning (WGPScanning) analysis of O157 strains, on the other hand, revealed a high level of genomic diversity in O157. Variation of prophages has also been suggested as a major factor generating such diversity.
In this study, we analyzed the gene content of O157 strains, by an oligoDNA microarray, using the same set of strains as examined by the WGPScanning method.
Although most of the strains were typical O157 : H7, they differed remarkably in gene composition, particularly in those on prophages, and we identified more than 400 'variably absent or present' genes which included virulence-related genes. This confirms the role of prophages in generating the genomic diversity, and raises a possibility that some level of variation in potential virulence is present among O157 strains. Fine comparison of the two datasets obtained by microarray and WGPScanning provided much further details on the O157 genome diversity than illustrated by each method alone, indicating the usefulness of this combinational approach in the genomic comparison of closely related strains.

DNA Res. 2006 Feb 28;13(1):3-14. Epub 2006 Feb 22.

Forage feeding to reduce preharvest Escherichia coli populations in cattle, a review.

Callaway TR, Elder RO, Keen JE, Anderson RC, Nisbet DJ.

Food and Feed Safety Research Unit, South Plains Agricultural Research Center,
Agricultural Research Service, USDA, College Station, TX 77845, USA.
callaway@ffsru.tamu.edu

Although Escherichia coli are commensal organisms that reside within the host gut, some pathogenic strains of E. coli can cause hemorrhagic colitis in humans.
The most notable enterohemorrhagic E. coli (EHEC) strain is O157:H7. Cattle are asymptomatic natural reservoirs of E. coli O157:H7, and it has been reported that as many as 30% of all cattle are carriers of this pathogen, and in some circumstances this can be as high as 80%. Feedlot and high-producing dairy cattle are fed large grain rations in order to increase feed efficiency. When cattle are fed large grain rations, some starch escapes ruminal microbial degradation and passes to the hind-gut where it is fermented. EHEC are capable of fermenting sugars released from starch breakdown in the colon, and populations of E. coli have been shown to be higher in grain fed cattle, and this has been correlated with E. coli O157:H7 shedding in barley fed cattle.
When cattle were abruptly switched from a high grain (corn) diet to a forage diet, generic E. coli populations declined 1000-fold within 5 d, and the ability of the fecal generic E. coli population to survive an acid shock similar to the human gastric stomach decreased. Other researchers have shown that a switch from grain to hay caused a smaller decrease in E. coli populations, but did not observe the same effect on gastric shock survivability. In a study that used cattle naturally infected with E. coli O157:H7, fewer cattle shed E. coli O157:H7 when switched from a feedlot ration to a forage-based diet compared with cattle continuously fed a feedlot ration. Results indicate that switching cattle from grain to forage could potentially reduce EHEC populations in cattle prior to slaughter; however the economic impact of this needs to be examined.

J Dairy Sci. 2003 Mar;86(3):852-60.

Comment in:
J Dairy Sci. 2004 Jun;87(6):1579.

PMID: 12703622 [PubMed - indexed for MEDLINE]

Related Links in Pubmed Database

Effect of forage or grain diets with or without monensin on ruminal persistence and fecal Escherichia coli O157:H7 in cattle. [Appl Environ
Microbiol. 2004] PMID:15345418

Acid resistance of Escherichia coli O157:H7 from the gastrointestinal tract of cattle fed hay or grain. [Vet Microbiol. 2003] PMID:12935748

The effect of different grain diets on fecal shedding of Escherichia coli O157:H7 by steers. [J Food Prot. 2000] PMID:11079685

Escherichia coli O157:H7 excretion by commercial feedlot cattle fed either barley- or corn-based finishing diets. [J Food Prot. 2004] PMID:15083716

Effect of supplementing corn- or barley-based feedlot diets with canola oil on faecal shedding of Escherichia coli O157:H7 by steers. [J Appl Microbiol.
2005] PMID:15659201


Guidance for Industry
Guide to Minimize Microbial Food Safety Hazards for Fresh Fruits and Vegetables
Food and Drug Administration U. S. Department of Agriculture Centers for Disease Control and Prevention October 26, 1998
Center for Food Safety and Applied Nutrition (CFSAN)