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Sprouts and Bacteria: It’s the Growing Conditions

Who would’ve guessed sprouts?  Who would have predicted that Germany’s E. coli outbreak, already one of the worst food poisoning epidemics in recent times, might be connected to a food that is virtually a cliché for health foods and vegetarians?

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Actually, that might have been the guess of anybody familiar with the recent history of foodborne illness outbreaks, because the experts know those seemingly innocuous raw sprouts can carry toxic bacteria.

In the last 20 years, contaminated bean sprouts, alfalfa sprouts or other varieties have been blamed for at least 40 significant outbreaks of foodborne illness across the U.S., Canada and Europe. Most of those incidents were blamed on Salmonella bacteria, but E. coli contamination has occurred as well.

They include what had been  considered the worst known outbreak of E. coli, a 1996 epidemic in Sakai City, Japan. In that case, nearly 10.000 people, most of them students and teachers served school lunches prepared in a central kitchen, were sickened with E. coli O157:H7.  At least 12 died from kidney failure and related complications.

Eventually, health officials determined the source of the outbreak was radish sprouts, grown on a Japanese farm from seeds that may have come from Oregon. No traces of the offending bacteria were ever found in sprouts.  But, as in other cases where the contaminated food is long gone, epidemiologists determined the cause by a process of elimination.

Japan has since attempted to retrain officials to respond quickly by interviewing victims of outbreaks.

But how would sprouts become contaminated with a toxin associated with cow excrement?

Blame it on healthy growing conditions, according to Dr. John Kobayashi, a veteran epidemiologist in Seattle who now teaches at the University of Washington.

Sprouts pose “an inherent problem” for foodborne illness, Kobahashi explains. If the sprout  seed becomes contaminated — perhaps by cow manure from a neighboring field — the sprouts can become a carrier.  Even worse, they become “an incubator,” he adds. The sprouts and bacteria are nurtured by precisely the same combination of heat and moisture. 

“The juice in the sprout container is inevitably loaded with bacteria, most of which are harmless.”

But if they are contaminated with toxic Salmonella or E. coli, the bacteria grow happily with the sprouts, and may survive a cold water wash.  Because the sprouts are almost always eaten uncooked, there is no “kill step,” no opportunity to heat the food and kill the offending bacteria.

“You could irradiate them,” Kobayashi adds.  ”But nobody seems to want that.”

In the case of Sakai City, the problem probably originated with the seeds, he says.  The bacteria gets into the cracks of the seeds.  When the seeds are sprouted, the bacteria thrives. They both end up in somebody’s salad.

 And, a week or so later, somebody gets sick.

© Food Safety News
  • https://sites.google.com/site/nosludgedumping No Sludge Dumping – Florida

    Reference your statement: “But how would sprouts become contaminated with a toxin associated with cow excrement?”
    It is NOT the cows. It is NOT cow manure. Rather, the culprit is “humanure,” human sewage / compost used as fertilizer. In Europe, human sewage used as fertilizer is termed manure. In the US, it is given more glitzy terms, i.e., biosolids, residuals, TSS. It will be interesting to see if the terms “humanure” or sewage sludge is ever used regarding this case.

  • doc raymond

    These pathogenic toxins do not reside in human intestines, except when the human is deathly ill. They DO reside in cow intestines with no toxic effect. Same as some non-pathogenic E coli inhabit our intestines. As Nancy Donley from STOP has said, if you investigate back far enough, for every case of human illness from E coli, you will eventually bump into a cow.

  • Minkpuppy

    No Sludge: And just what scientific research are you basing your assumption on? Cattle have always been a known source of STEC E.coli and it’s back up with tons of research. Haven’t heard the same about “humanure.”
    If toxic E.coli is being generated in humans, don’t ya think the humans carrying it would be sick?

  • Doc Mudd

    Fair enough, Doc R. – there’s a cow at the source of every O157:H7 event, but along the way between here and there you will inevitably encounter a human SOB (or several) who’s screwed up his/her safety protocols.
    Negligence resides with the Human SOB(s), no point in prosecuting the cow.

  • doc raymond

    Everyone who reads my blogs knows I do not want to prosecute the cows, I want to vaccinate them and help clean up the environment.

  • http://www.walkingjfarm.com Farmer T

    Cows in the nearby farm eating grass are not the culprits. A cow eating straight grass does not have these new strains of e.coli in their gut. It is the feedlot cattle, stuffed with yellow dent #5 (gmo corn) and over 1/2 the world’s antibiotics to keep them alive on an unnatural diet (for a cow), that are creating the super bug e.coli strains we are seeing today. That manure is taken to farms as fertilizer and leaches from the feedlots into aquifers (we’re talking hundreds of thousands of cows in one spot, not the nearby farm with its 5 head of cattle). Vaccinating cows is not the answer. Doing away with the feedlot model and allowing cows to eat what they have evolved eating is the answer.

  • mrothschild

    Farmer T: Studies have shown that grass-fed cows can harbor E. coli O157:H7 at rates nearly the same as grain-fed cattle. One study even showed a higher prevalence of O157:H7 in the excrement of grass-fed cows. Recent research does indicate that O157:H7 may be more prevalent for cattle that are fed corn-based wet distiller’s grains with solubles in the last months before slaughter, but from a consumer’s point of view, this really doesn’t matter — it takes so few of these bacteria to cause illness that people should understand that pathogenic E. coli can contaminate both grass-fed and grain-fed beef. There are reasons to choose grass-fed beef — it tastes great and may even be more nutritious than feedlot beef, for example, and I personally like to support my local farmers — but don’t be complacent about safety. Beef from grass-fed cattle still must be cooked thoroughly. Misinformation like yours is very dangerous.

  • http://www.walkingjfarm.com Farmer T

    Which study are you referencing? I would like to read it.

  • mrothschild

    Studies — not just one study. Here is one of the latest; you can find the long list (40 citations) of other, previous studies in Bill Marler’s blog entry from 2008. I’ve provided that link as well.
    “Contamination Rates and Antimicrobial Resistance in Bacteria Isolated from “Grass-Fed” Labeled Beef Products” by Jiayi Zhang, Samantha K. Wall, Li Xu, Paul D. Ebner in Foodborne Pathogens and Disease
    http://www.marlerblog.com/lawyer-oped/grass-fed-vs-grain-fed-beef-and-the-holy-grail-a-literature-review/
    Also, as a point of interest, the cause of the 2000 Walkerton, Canada E. coli outbreak, which sickened 2,300 people, was found to be water contaminated by manure from a small herd of grass-fed cows on a hobby farm. And following the 2006 E. coli outbreak caused by spinach grown in California, the outbreak strain was isolated in both nearby pastured cows and a wild boar killed in one of the fields – animals that had eaten nothing but grass.
    This is an interesting debate and more research is needed. As I stated before, grass-fed beef has many merits, but it is dangerous to suggest that it is a guarantee of safety. It is not.

  • Mary Rothschild

    Farmer T: Studies have shown that grass-fed cows can harbor E. coli O157:H7 at rates nearly the same as grain-fed cattle. One study even showed a higher prevalence of O157:H7 in the excrement of grass-fed cows. Recent research does indicate that O157:H7 may be more prevalent for cattle that are fed corn-based wet distiller’s grains with solubles in the last months before slaughter, but from a consumer’s point of view, this really doesn’t matter — it takes so few of these bacteria to cause illness that people should understand that pathogenic E. coli can contaminate both grass-fed and grain-fed beef. There are reasons to choose grass-fed beef — it tastes great and may even be more nutritious than feedlot beef, for example, and I personally like to support my local farmers — but don’t be complacent about safety. Beef from grass-fed cattle still must be cooked thoroughly. Misinformation like yours is very dangerous.

  • Mary Rothschild

    Studies — not just one study. Here is one of the latest; you can find the long list (40 citations) of other, previous studies in Bill Marler’s blog entry from 2008. I’ve provided that link as well.
    “Contamination Rates and Antimicrobial Resistance in Bacteria Isolated from “Grass-Fed” Labeled Beef Products” by Jiayi Zhang, Samantha K. Wall, Li Xu, Paul D. Ebner in Foodborne Pathogens and Disease
    http://www.marlerblog.com/lawyer-oped/grass-fed-vs-grain-fed-beef-and-the-holy-grail-a-literature-review/
    Also, as a point of interest, the cause of the 2000 Walkerton, Canada E. coli outbreak, which sickened 2,300 people, was found to be water contaminated by manure from a small herd of grass-fed cows on a hobby farm. And following the 2006 E. coli outbreak caused by spinach grown in California, the outbreak strain was isolated in both nearby pastured cows and a wild boar killed in one of the fields – animals that had eaten nothing but grass.
    This is an interesting debate and more research is needed. As I stated before, grass-fed beef has many merits, but it is dangerous to suggest that it is a guarantee of safety. It is not.

  • Cherub

    : ) Sorry… something about a Rothschild ranting about misinformation really tickles my funny bone… No offence… Sorry that’s just funny.