Biofilms help Shiga-toxin producing E. coli survive and persist

Forming biofilms may be a survival strategy of Shiga toxin-producing Escherichia coli to enable it to persist in the environment and the food industry.

e.coli.biofilm

Here, we evaluate and characterize the biofilm-forming ability of 39 isolates of Shiga toxin-producing Escherichia coli isolates recovered from human infection and belonging to seropathotypes A, B, or C.

The presence and/or production of biofilm factors such as curli, cellulose, autotransporter, and fimbriae were investigated. The polymeric matrix of these biofilms was analyzed by confocal microscopy and by enzymatic digestion. Cell viability and matrix integrity were examined after sanitizer treatments. Isolates of the seropathotype A (O157:H7 and O157:NM), which have the highest relative incidence of human infection, had a greater ability to form biofilms than isolates of seropathotype B or C. Seropathotype A isolates were unique in their ability to produce cellulose and poly-N-acetylglucosamine.

The integrity of the biofilms was dependent on proteins. Two autotransporter genes, ehaB and espP, and two fimbrial genes, z1538 and lpf2, were identified as potential genetic determinants for biofilm formation. Interestingly, the ability of several isolates from seropathotype A to form biofilms was associated with their ability to agglutinate yeast in a mannose-independent manner. We consider this an unidentified biofilm-associated factor produced by those isolates.

Treatment with sanitizers reduced the viability of Shiga toxin-producing Escherichia coli but did not completely remove the biofilm matrix. Overall, our data indicate that biofilm formation could contribute to the persistence of Shiga toxin-producing Escherichia coli and specifically seropathotype A isolates in the environment.

Biofilm-forming abilities of Shiga toxin-producing Escherichia coli isolates associated with human infections

Applied and Environmental Microbiology Vol. 82. No. 5.

http://dx.doi.org/10.1128/AEM.02983-15.

Depends: Does slow cooking beef roasts get rid of E. coli O157?

Inactivation of Escherichia coli O157:H7 in beef roasts cooked under selected cooking conditions was evaluated.

eye.round.roast.slow.cookerEye of round roasts were each inoculated at five sites in the central plane with a five-strain cocktail of E. coli O157:H7 at ca. 6.3 log CFU per site and cooked to center temperatures of 56 to 71°C in a convection oven set at 120, 140, 180, or 200°C, in a conventional oven set at 120 or 210°C, and in a slow cooker set on high or low.

Prime rib roasts were each inoculated at 10 sites throughout the roast with the same E. coli O157:H7 cocktail at ca. 6.6 log CFU per site and cooked in the conventional oven set at 140 or 180°C to center temperatures of 58 to 71°C.

The number of sites yielding E. coli O157:H7 after cooking decreased with increasing roast center temperature for the eye of round roasts cooked in the convection oven or in the slow cooker at a given setting, but this trend was not apparent for roasts of either type cooked in the conventional oven. Reductions of E. coli O157 in both types of roasts were generally less at the center than at other locations, particularly locations closer to the surface of the meat. When eye of round roasts were cooked to the same center temperature in the convection oven, the reduction of E. coli O157:H7 increased with increasing oven temperature up to 180°C and decreased after that. The reduction of E. coli O157:H7 in replicate roasts cooked under conditions in which the organism was not eliminated during cooking mostly differed by >1 log CFU per site. However, E. coli O157:H7 was not recovered from any of the inoculation sites when eye of round roasts were cooked to 65, 60, 60, or 63°C in the convection oven set at 120, 140, 180, and 200°C, respectively; cooked to 63 or 71°C in the conventional oven set at 120 and 210°C, respectively; or cooked to 63°C in the slow cooker set at high or low.

For prime rib roasts, E. coli O157:H7 was not recovered from any of the inoculation sites in roasts cooked to 71 or 58°C in the conventional oven set at 140 and 180°C, respectively.

Inactivation of Escherichia coli O157:H7 in beef roasts cooked in conventional or convection ovens or in a slow cooker under selected conditions

Journal of Food Protection®, Number 2, February 2016, pp. 184-344, pp. 205-212(8)

Gill, C. O.; Devos, J.; Badoni, M.; Yang, X.

http://www.ingentaconnect.com/content/iafp/jfp/2016/00000079/00000002/art00003

Surveys still suck but this involves Chipotle, so it’s fun (for me)

The Daily Meal asked the public what impact, if any, the six-foodborne-illness-outbreaks-in-six months has had on the number of times they dine at Chipotle.Dan Myers writes 450 people responded, and here are the results:

chipotle.slide.jan.16I’ve never eaten at Chipotle, and I’m not about to start now:  5.9%

I’ve cut back on dining there, but haven’t completely stopped: 6.8%

I held off during the outbreak, but will start eating there again now that it’s over: 13.8%

It didn’t affect my Chipotle addiction at all: 21.8%

I’ve stopped dining there completely: 46.5%

Nearly half of all respondents have sworn off Chipotle completely, while only a relatively small percentage is planning on returning at all! At the other end of the spectrum, however, more than 20 percent of respondents remained loyal throughout the outbreak, food poisoning risk be damned. These loyalists weren’t enough to fend off a major drop in sales, however.

Chipotle has spent millions of dollars trying to woo customers back, and will continue to spend more, and the chain is confident that this plan will work. But if nearly half of its customer base swears the chain off for good, can it ever really recover?

E. coli O26 causing HUS in infants in Romania

Health Minister Patriciu Achimas-Cadariu told a news conference on Thursday that E. coli O26 was the cause of hemolytic-uremic syndrome that sickened infants of Arges County (numbers not provided).

ecoli-1184pxAs far as the management of the Arges Public Healthcare Directorate is concerned, the minister said the control team of the Health Ministry is conducting an investigation that should end on March 4.

Do labels work? Should sprouts come with a warning label?

NPR reports that for something many deem a “health food,” sprouts regularly appear on official outbreak lists. Since 1998 there have been at least 49 foodborne outbreaks, including 24 multi-state outbreaks and 1,737 illnesses tied to sprouts, according to a tally kept by Colorado State University.

amy.sprouts.guelph.05Sandwich chain Jimmy John’s experienced multiple outbreaks linked to sprouts in 2008, 2009, 2010 and 2012. Sprouts are still on the menu, but place your order online, and a less than appetizing warning pops up: “The consumption of raw sprouts may result in an increased risk of foodborne illness and poses a health risk to everyone. Click ‘Yes’ if you understand the potential risks, or ‘Cancel’ if you’d like to continue without adding sprouts.”

Jimmy John’s may feel comfortable behind their warning label, but offering sprouts is a risk that Kroger and Wal-Mart no longer take — both grocery retailers have deemed sprouts too dangerous to sell. In announcing its decision in 2012, Kroger said it was based on a “thorough, science-based” review.

Sprout seeds need warmth and humidity to grow — which also happen to be ideal conditions for pathogens to flourish. Because of the number of outbreaks associated with sprouts, the FDA developed special requirements for sprout growers within the Food Modernization and Safety Act that is just going into effect. A few years ago, the agency also helped launch the Sprout Safety Alliance, with the Institute for Food Safety and Health at the Illinois Institute of Technology.

Linda Harris, a microbiologist at University of California, Davis, says sprouts continue to be a problem because they’re challenging. Whether they’re alfalfa, mung bean, red clover or radish sprouts, they’re grown in warm environments and usually eaten raw.

“Efforts to reduce risk include testing seed, testing seed water. Soaking seed in sanitizers is another — none of which are foolproof,” says Harris. “It reduces risk, but the fact is, we still see outbreaks on a regular basis.”

Continued outbreaks are one reason lawyer Bill Marler has been crusading for a warning label similar to the one adopted by Jimmy John’s. At least, until a magic bullet emerges to fix the problem. Harris says that hasn’t happened yet.

“I think there’s been an effort to find some solution, but honestly, as a microbiologist, I think [sprouts are] always going to be a higher-risk product, at least under current technology,” says Harris.

9 sick with E. coli O157: Jack & The Green Sprouts

The U.S. Centers for Disease Control and Prevention reports that nine people infected with the outbreak strain of Shiga toxin-producing Escherichia coli O157 (STEC O157) have been reported from two states: Minnesota (7) and Wisconsin (2).

Jack & The Green SproutsTwo ill people have been hospitalized. No one has developed hemolytic uremic syndrome, a type of kidney failure, and no deaths have been reported.

Collaborative investigative efforts of state, local, and federal public health and regulatory officials indicate that alfalfa sprouts produced by Jack & The Green Sprouts of River Falls, Wisconsin are a likely source of this outbreak. These sprouts may be contaminated with STECO157 and are not safe to eat.

Of the eight people interviewed, all eight (100%) ill people reported eating or maybe eating alfalfa sprouts or menu items containing alfalfa sprouts in the week before they became ill.

Illnesses started on dates ranging from January 17, 2016 to February 8, 2016. Ill people range in age from 17 years to 84, with a median age of 28. Sixty-six percent of ill people are female.

State and local health and regulatory officials performed traceback investigations from seven different locations where ill people ate or bought alfalfa sprouts. These investigations indicated that Jack & The Green Sprouts supplied alfalfa sprouts to all seven locations.

We recommend that consumers do not eat and restaurants and other retailers do not sell or serve alfalfa sprouts produced by Jack & The Green Sprouts at this time.

This outbreak does not appear to be related to the ongoing multistate outbreak of Salmonella Muenchen infections linked to alfalfa sprouts produced by Sweetwater Farms of Inman, Kansas.

This investigation is ongoing, and we will update the public when more information becomes available.

We don’t need no stinkin’ buffer zones – except to protect produce

Tom Karst of The Packer reports that current food safety guidelines on the proximity of cattle feedlots and leafy greens crops may not be enough to prevent the airborne spread of the E. coli pathogen.

cow.poop2__1.story_“Current leafy green field distance guidelines of 120 meters (400 feet) may not be adequate to limit the transmission of E. coli O157:H7 to produce crops planted near concentrated animal feeding operations,” the authors of the study said.

The study’s nine authors include researchers from the U.S. Department of Agriculture’s U.S. Meat Animal Research Center, Clay Center, Neb., the University of California-Davis, and the USDA’s Beltsville Agricultural Research Center, Beltsville, Md.

Trevor Suslow, plant pathologist with the University of California-Davis and one of the authors of the study, said the research indicates that proximity to large concentrated animal operations calls for extra diligence in determining risk and in putting in place processes that monitor potential contamination.

FDA produce safety regulations do not specify setback distances between leafy greens fields and cattle feedlots, although the Leafy Greens Marketing Agreement in California, followed by many other organizations, put the number at 400 feet, he said.

“Many times 400 feet is more than enough separation based on position relative to prevailing winds and other times it can clearly result in contamination,” he said. “It is not a simple formula to say everything has to be a mile between feedlot operations. That could make production very difficult in most places,”  he said.

Suslow said another part of the study, not published yet, looks at the role of certain types of flies that can carry bacteria from feedlot operations to fields.

Effect of proximity to a cattle feedlot on Escherichia coli O157:H7 contamination of leafy greens and evaluation of the potential for airborne transmission

Appl. Environ. Microbiol. February 2015 vol. 81 no. 3 1101-1110

Elaine D. Berry, James E. Wells, James L. Bono, Bryan L. Woodbury, Norasak Kalchayanand, Keri N. Norman, Trevor V. Suslow, Gabriela López-Velasco and Patricia D. Millner

http://aem.asm.org/content/81/3/1101.long

Abstract

The impact of proximity to a beef cattle feedlot on Escherichia coli O157:H7 contamination of leafy greens was examined. In each of 2 years, leafy greens were planted in nine plots located 60, 120, and 180 m from a cattle feedlot (3 plots at each distance).

Leafy greens (270) and feedlot manure samples (100) were collected six different times from June to September in each year. Both E. coli O157:H7 and total E. coli bacteria were recovered from leafy greens at all plot distances. E. coli O157:H7 was recovered from 3.5% of leafy green samples per plot at 60 m, which was higher (P < 0.05) than the 1.8% of positive samples per plot at 180 m, indicating a decrease in contamination as distance from the feedlot was increased.

Although E. coli O157:H7 was not recovered from air samples at any distance, total E. coli was recovered from air samples at the feedlot edge and all plot distances, indicating that airborne transport of the pathogen can occur.

Results suggest that risk for airborne transport of E. coli O157:H7 from cattle production is increased when cattle pen surfaces are very dry and when this situation is combined with cattle management or cattle behaviors that generate airborne dust.

Current leafy green field distance guidelines of 120 m (400 feet) may not be adequate to limit the transmission of E. coli O157:H7 to produce crops planted near concentrated animal feeding operations. Additional research is needed to determine safe set-back distances between cattle feedlots and crop production that will reduce fresh produce contamination.

10 sick with E. coli O157: Link to raw milk in California

The Spongebob cone of silence – usually reserved for leafy greens, cantaloupes and sometimes tomatoes has finally been lifted on an E. coli O157 outbreak involving raw milk in California.

colbert.raw.milkRobert Rodriquez of The Fresno Bee reports Organic Pastures Dairy in Fresno County voluntarily recalled its raw milk last month after internal tests found evidence of E. coli. The tainted milk caused at least 10 illnesses, with six of those victims reporting they drank Organic Pastures raw milk, said California Department of Public Health officials.

The victims all had closely related strains of E. coli O157, the health department said.

Dairy owner Mark McAfee said that in early January the company voluntarily recalled the milk within 36 hours of determining the presence of E. coli.

McAfee said the cow had E. coli from a rare form of mastitis, an inflammation of the mammary gland in a cow’s udder.

Once the milk was found to be contaminated, the dairy stopped making milk and recalled the product. McAfee said only two of the dairy’s 40 routes – Northern California and the Central Coast – got the bad milk.

The dairy has since resumed milk production.

McAfee said the dairy has been talking with the families of some of those made ill from the milk. Of the victims – McAfee said there are only five – one is a 3-year-old from Fresno and the other is a 13-year-old from the Solvang area.

The two young victims were hospitalized and later released.

spongebob.oil.colbert.may3.10“We own this,” McAfee said. “We are in discussions over taking care of the medical costs for the child in Fresno and the one on the coast. We take this very seriously.”

McAfee said the child in Fresno drank contaminated milk purchased from the store on the dairy’s property near Kerman.

On Feb. 9, McAfee said, “Our food safety program saved the day. It worked extremely well. We’re proud of that.”

Not sure the 10 with E. coli O157 feel that way.

9 sick with E. coli O157: Sprouts strike again and again and again

A day after publicly announcing that nine people were sick from Salmonella in sprouts in Kansas and Oklahoma, nine people have been sickened with E. coli O157:H7 in alfalfa sprouts in Minnesota and Wisconsin.

Jack & The Green SproutsMinnesota health and agriculture officials are looking into an outbreak of foodborne illness tied to alfalfa sprouts produced by the firm Jack & The Green Sprouts.

Routine disease monitoring identified seven cases of E. coli in January and early February, all with the same DNA fingerprint, the Minnesota Health Department said in a statement Wednesday. The illness affected people ages 18 to 84; five were female. Four were in the Twin Cities metro area, with three in greater Minnesota. Two were hospitalized, and all have recovered, the department said.

Two additional Wisconsin cases were considered part of the outbreak, but no one was hospitalized.

Sprouts are a well-known source of foodborne illness, and epidemiologist Amy Saupe said there aren’t many ways to minimize the risk.

“It can’t be washed off, so even if people are being diligent and washing their sprouts prior to eating them, that won’t actually help at all to remove any of that bacterial contamination,” she said. “They can be thoroughly cooked before eating them, that can lower the risk. However these particular sprouts should definitely not be eaten at all.”

Jack & The Green Sprouts is based in River Falls, Wis., and distributes alfalfa sprouts to states in the upper Midwest and possibly other states. Minnesota health officials urged retailers and restaurants to not sell or serve alfalfa sprouts produced by Jack & The Green Sprouts and said consumers should not eat them at this time.

“The seven Minnesota cases and at least one of the Wisconsin cases were exposed to implicated alfalfa sprouts from a variety of locations, including grocery/cooperative stores, restaurants, salad bars and commercial food service,” the state health agency said.

A table of sprout-related outbreaks can be found at https://barfblog.com/wp-content/uploads/2016/02/Sprout-associated-outbreaks-2-24-16.xlsx

Food is getting safer, but still might make you sick

Scott Canon of The Kansas City Star writes in a good food safety feature, go ahead and eat out. Or eat in (edited excerpts below).

produceWhether you dig into Mom’s casserole, feast on the local diner’s daily special or snarf up something from a mega-corporation’s drive-through, America’s meals may arrive as safe now as mankind has ever known.

Just not 100 percent.

Government rules continue to tighten. Various industries, fearful of lawsuits and the lost business that follows bad publicity, put more muscle into keeping things clean.

Yet experts also describe an increasingly elaborate system that tests the power to keep a meal safe.

“The marketplace is probably more complex,” said Charles Hunt, the Kansas state epidemiologist. “The produce that you get in the store today was in Mexico or someplace else just a few days before.”

The Chipotle chain saw multiple, high-profile problems last year. An E. coli outbreak traced to its restaurants in October. In December, the company also was tied to a norovirus incident in Boston, following outbreaks of the pathogen earlier in the year at outlets in California and Minnesota.

In the Kansas City area, more than 600 people got sick after attending shows at the New Theater Restaurant in January, and tests confirmed infections of the norovirus in at least some. It also struck at least 18 staff and patients at the University of Kansas Hospital’s Marillac Campus that month. And about a dozen people were hit with the same vomiting and diarrhea shortly afterward at a Buffalo Wild Wings in Overland Park.

Upticks in detections of outbreaks of food-borne illness, analysts say, likely reflect our increasing powers to spot them — not a growing danger.

In 1998, the U.S. Food and Drug Administration traced an outbreak of salmonella agona to a Malt-O-Meal processing plant in Minnesota. Ten years later, the same plant again shipped out cereal tainted with salmonella, sickening at least 33 people.

With the two incidents separated by a decade, any link seemed coincidental.

But a few years later, the FDA built a powerful tool for analyzing bacterial strains — Whole Genome Sequencing. It can identify down the lineage of any bacterium in its database. In this case it showed the new salmonella was the direct descendant of the earlier one.

barfblog.Stick It InIt turned out that the first outbreak stemmed from contaminated water used to clean the plant during a renovation. That same water was mixed in with mortar for the construction. Dangerous salmonella had been preserved in that mortar. Over the years, the surface of the mortar turned to dust, got wet and gave new life to that distinct family of salmonella.

Imagine the implications. The plant could prevent repeats by painting a sealant over the unlikely culprit — mortar in its walls.

But think of the child who becomes sick down the road with salmonella. The source could be any of thousands of ingredients consumed by an American kid in a normal day. But what if a doctor shares the salmonella sample with federal disease trackers? By looking at the particular genetic line, scientists can spot the family tree and the likely source.

“It tells you who’s related to who even over many years,” said Eric Brown, the director of the Division of Microbiology at the FDA’s Center for Food Safety & Applied Nutrition.

Technology, food safety experts say, only goes so far.

The bigger payoffs come from diligence. That means, foremost, avoiding contamination from feces.

“Our food safety starts on the farm,” said Doug Powell. A former Kansas State University professor of food safety, he’s now the chief author of barfblog.

“It has to be systemic, repeated and relevant.”

For starters, farmers should not use manure on fresh produce. They need to know where their irrigation supply comes from and whether runoff during heavy rains travels from feedlots or other places where livestock or farm workers defecate. Washing those fruits and vegetables later down the line is necessary, but that often can’t overcome massive exposure to E. coli and other potentially fatal bacteria that thrive in poop.

Bill Marler, a Seattle attorney who’s made a high-profile career filing lawsuits in food-borne illness cases, speaks with less alarm about the direction of Big Meat.

After years of restaurants and meat packers weathering expensive lawsuits and public relations disasters, he said, they’ve changed.

Take the slaughterhouse. Cattle arrive splattered with barnyard waste. For years, that created problems because the tainted hides would inevitably taint the skinned carcasses. But now, packing operations routinely steam-clean or treat the carcasses with an acid wash.

“You started to see an amazing turnaround and recalls linked to hamburger have fallen like a stone,” Marler said.

Meantime, he said, restaurants better recognize the business risk of not killing pathogens that cling to meat. Marler said big chains, in particular, devote increasing effort to thoroughly cooking beef, pork and poultry.

And federal rules on the required temperature for cooked meat have increased. Some chains, such as Taco Bell, now cook meat at centralized locations before shipping it to franchises. The local teenager preparing that food for customers still needs to be wary of temperature control, but much of the responsibility for safety has been standardized by corporate operations.

Produce, he and others say, poses a more difficult problem. Food that’s not cooked lacks the critical “kill step” to render harmless the bacteria that do slip through.

That, goes the critique, sets up a corporate culture that valued freshness over safety.

The company has responded by shutting down its restaurants repeatedly for special training days and saying its redoubled efforts to track the practices of its suppliers.

(Many have noted that much of Chipotle’s problems related to contamination from sick workers, not from its pursuit of freshness. More on that later.)

food-handler-card-skillsBut consumers have shown an increasing interest in the source of their food, preferring fresh over processed and local or organic over cheaper commodity ingredients. That’s tied, analysts say, to the belief that food made on a smaller scale and without the use of antibiotics in livestock or pesticides in crops is safer.

Some evidence suggests that such methods provide a more nutritious meal that may avoid long-term health risks. Yet they can pose new challenges in dodging food-borne pathogens in the short term, said barfblog’s Powell and others.

“Natural, organic, sustainable, dolphin-free — those are lifestyle choices,” Powell said. “There’s been no study that has conclusively said one way or another if it’s more likely to make you barf more.”

He worries it might. Smaller farms might not have the resources, or the sophistication, to keep soiled rain runoff from their vegetable patches. The farmer’s market customers or restaurants drawn to their farm-to-plate marketing, he said, might be less inclined to question safety.

“McDonald’s has it covered,” Powell said. “At the boutique places, I say I want my meat cooked to 165 degrees and they look at me like I just came off the turnip truck.”