Emerging Disease and Zoonoses #22–Popeye never warned you about this

E. coli outbreak traced to tainted spinach

An outbreak of E. coli in eight states has left at least one person dead and 50 others sick, federal health officials said Thursday in warning consumers nationwide not to eat bagged fresh spinach.

The death occurred in Wisconsin, where 20 others were also sickened, said Dr. David Acheson of the Food and Drug Administration’s Center for Food Safety and Applied Nutrition. The outbreak has sickened others — eight of them seriously — in Connecticut, Idaho, Indiana, Michigan, New Mexico, Oregon and Utah.

FDA officials do not know the source of the outbreak other than it appears to be linked to bagged spinach. “We’re advising people not to eat it,” Acheson said.

(More below)

The CNN article doesn’t specifically say that the E. coli causing disease is serotype O157:H7, but the FDA website gives that information. O157:H7, of course, is the strain that’s received the lion’s share of attention over the past decade, due to the fact that it’s caused large outbreaks and has the potential to be fatal (as it was in one of these recent cases), causing bloody diarrhea and kidney damage. Typically, outbreaks have been due to contamination of foods with manure from cattle (who harbor the bacterium in their feces).

Though 50 cases have been reported thus far, they still don’t know a lot about the spinach that’s causing the outbreak:

Preliminary analysis suggests the same bug is responsible for the outbreak in all eight states.

The warning applied to consumers nationwide because of uncertainty over the origin of the tainted spinach and how widely it was distributed.

Health officials do not know of any link to a specific growing region, grower, brand or supplier, Acheson said.

He said reports of infections have been growing.

“It’s increasing by the day,” Acheson said. “We may be at the peak, we may not be.”

This uncertainty is why the FDA made the recommendation mentioned above suggesting people simply not eat bagged spinach for the time being.

This isn’t the first time that bagged salad products have been linked to an outbreak of E. coli. Spinach was the culprit in a 2004 outbreak, and romaine lettuce sickened people earlier this year. Dateline NBC even did a “Danger lurking in your salad” piece last month.

Does this mean you shouldn’t eat bagged salad products? I’d say no more than it should keep you from eating apples, or ground beef, or other foods that have been previously involved in outbreaks of food-borne illness. I eat these bagged salads pretty regularly since they make for a real quick meal, but even though they’re pre-washed, I wash them again for good measure. Will this prevent all chance of disease, if the lettuce happens to be contaminated? Nope. Nothing is foolproof, but despite Dateline’s story, luckily these types of outbreaks are fairly rare. Small comfort, of course, for anyone who’s infected in this manner (or worse, whose child is).

*Bonus question, especially for our resident HIV “rethinkers” who make much of the issue that HIV seems to preferentially infect women. Why is it, do you think, that women are disproportionately affected in this outbreak?

[Edited to add: Mike had the same idea. Be sure to check his post out for some more info on E. coli in general.]

Image from http://www.math.pitt.edu/~bard/bardware/popeye/spinach.gif

Comments

#1 J-Dog
September 15, 2006

Thanks Tara! I sent this to my wife and daughter who are salad fanatics and on their way back to school, and what proably would have been a salad for lunch.

BTW – Like your graphic!
#2 Skeptico
September 15, 2006

Yeah, but Popeye may have used the “spinach” in his pipe! Just sayin…
#3 Ruth
September 15, 2006

Popeye ate the canned stuff, so he was in danger from botulism, not E. coli. Maybe that’s why my mom cooked all veggies to a mush.
#4 W. Kevin Vicklund
September 15, 2006

Tara, my wife is doing her dissertation research on an E. coli-related topic. She sent me an excerpt from a book and a follow-up news article on a possible vaccine for E. coli – but the vaccine has a bit of a twist. Want me to forward that to you? Warning -it is a little bit dated, so I don’t know where the research currently stands.
#5 Tara C. Smith
September 15, 2006

Sure, send it on along: aetiology AT gmail DOT com.

Skeptico, never heard about Popeye being a stoner, but I suppose that makes more sense in a lot of ways than acutal spinach…
#6 PhysioProf
September 15, 2006

One of the morning news shows–I forget which one–was asserting that the bacteria were entering the roots of the plants from contaminated irrigation water, and were actually inside the leaves. On this basis, they further asserted that washing the leaves before eating would not help prevent ingestion of the bacteria.

Does this make any sense?
#7 Tara C. Smith
September 15, 2006

Interesting. Plants are the thing I probably know least about, so I can’t really comment on that. Certainly the irrigation water could be contaminated, and bacteria can definitely be found in plant roots, but I don’t know how common it is for E. coli and whether it’s common for the bacteria to make it to the leaves. Any botanists in the house?
#8 eduranter
September 15, 2006

PhysioProf,
The 1995 outbreak of E Coli associated with alfalfa sprouts was attributed to contaminated seeds, so this would not be surprising.
#9 Mike the Mad Biologist
September 15, 2006

Bonus question, especially for our resident HIV “rethinkers” who make much of the issue that HIV seems to preferentially infect women. Why is it, do you think, that women are disproportionately affected in this outbreak?

Failure to use condoms? Ok, I’ll stop now…
#10 KevinC
September 15, 2006

The irrigation water is moved through the plant via transpiration, don’t see why the E. coli wouldn’t get sucked up with the water, it is really a physical process and not a biochemical one. Because it would be via transpiration they would end up in the leaves because the stomata’s are mostly in leaves.

I am graduating in December with a BS in Environmental Science, Biology with alot of lab experiance in microbiology from Northern Arizona University in Yuma (winter lettece capitol of the world) and was thinking about trying to get a job with one of the packing houses. What a responsability, but a year would clean the loan slate before grad school.
#11 Joseph O'Donnell
September 16, 2006

Plants are the thing I probably know least about, so I can’t really comment on that. Certainly the irrigation water could be contaminated, and bacteria can definitely be found in plant roots, but I don’t know how common it is for E. coli and whether it’s common for the bacteria to make it to the leaves. Any botanists in the house?

Plants have a relatively ‘open’ vascular system and take up water primarily by a mechanical process. This means that they can pump a bacterium or other thing all the way around their body and into other things including leaves/fruit. Interestingly, this has led to occasions where Escherchia coli O157:H7 has been able to infect people through apple cider. Although cider is acidic, E. coli is well prepared for dealing with such an acidic environment and can survive the process involved.

Contaminated ground water on a farm can be just as much as a problem in plants as having animals infected with human pathogens can be.
#12 suirauqa
September 16, 2006

I was worried about the outbreak since it appears to have reached New York as well. According to CDC till yesterday (Sept 15, ’06):

As of September 15, 94 persons infected with the outbreak strain have been reported to CDC from 20 states. E. coli O157 causes a diarrheal illness. Among the ill persons, 29 (31%) were hospitalized, 14 (15%) developed a type of kidney failure called hemolytic-uremic syndrome (HUS), and an adult in Wisconsin died.

However, I was reasonably relieved because:

E. coli O157 is highly susceptible to heat. For example, E. coli strains in water are killed after 1 minute of boiling. Cooking vegetables well will kill E. coli.

As a matter of culture and customs perhaps, almost all foods in the Indian subcontinent are cooked and cooked thoroughly, being boiled in water or oil, well above the CDC recommended 160 deg F (71 degree C).

And this is for Tara and spinach-in-salad fans:

Bacteria stick to produce even when it is washed, and sometimes the bacteria are inside the produce.

According to CDC, antibacterials are not required for treatment, and they even advise against anti-diarrhoeal, such as loperamide (imodium). I wonder if there is some benefit in my grandmother’s favorite fix for ‘loose bowels’: eat more yogurt. Apparently, the friendly lactobacilli may displace the enteropathogenic E. coli and help replenish the gut microflora following a strong antibiotic therapy.
#13 Tara C. Smith
September 16, 2006

According to CDC, antibacterials are not required for treatment, and they even advise against anti-diarrhoeal, such as loperamide (imodium).

Yeah, antibiotics stress the cells, causing them to release phage, which carry the toxin. More toxin=more damage, so antibiotics aren’t used for O157 treatment. I wonder if irradiation would work to kill them, since it seems everything else doesn’t help much? (And cooked spinach–yuck).
#14 suirauqa
September 16, 2006

This particular paradox – kill bacteria with antibiotic, release more toxin – exists for another bacteria, Streptococcus pneumoniae. Death and lysis of the bacteria are hypothesized to release a toxin, pneumolysin, which is a potent inflammatory mediator and inducer of tissue damage. However, at least in Strep pneumoniae, it is important to kill the bacteria to stem the disease (usually with an appropriate beta-lactam or a macrolide, or fluoroquinolones in special circumstances), and the inflammation is taken care of independently if required. I understand that the toxin is the major problem in an 0157 infection; this is an area where a therapeutic vaccine may be of immense help.

Tara, spinach is basically an herb, and therefore, properly cooked spinach may not be so yucky after all. Tell me, is there no Indian restaurant in the Iowa city area? Try one, and ask for Palak Paneer. It is basically chunks of homemade cottage cheese (paneer) cooked in a spicy curry containing spinach (palak), to be taken with white rice. I have been told by my American friends that it actually tastes adequately good for the otherwise-bland American palate!
#15 Tara C. Smith
September 16, 2006

Oh, I love Indian food (the spicier the better), and I don’t mind spinach mixed in stuff, but just to eat it alone–no thanks.

And indeed, as with so many areas, a vaccine would be ideal. As Kevin mentioned earlier, there is work on a vaccine for cattle (see this news story, for instance.) Eliminating the source of the problem without having to go through human trials would be a big benefit.
#16 viji
September 17, 2006

Well.. that comment by suirauqa have really gottne my gastronomic juices going. I know of a simple spinach dish thats pretty easy to prepare and yummy. I thinks its a Malay-Chinese fusion dish, where you mix in spicy prawn paste, some garlic, and crispy dried shrimps, a quick stir fry of spinach in the mix, and garnish with freshly chopped chilis. Just divine with rice, especially on a cold Melbourne everning.
#17 jaimito
September 17, 2006

Contaminated ground water on a farm can be just as much as a problem in plants as having animals infected with human pathogens can be.

Not probable. Irrigation water from aquifers is sterile, water infiltrated carries no pathogens and they could not survive.

Moreover, most irrigation systems are disinfected with chlorine, to avoid formation of biofilm.

I bet the contamination is at a packing house, in its water supply. Field bacteria is supposed to be washed away at the packing stage.

BTW, is there a documented case of bacteria transported from soil to leaves by the plant? I never heard of that.
#18 DDS
September 17, 2006

Tara said “Yeah, antibiotics stress the cells, causing them to release phage, which carries the toxin. More toxin=more damage, so antibiotics aren’t used for O157 treatment.”

The phage certainly carry the toxin gene but I don’t think there is any evidence that release of a phage during a human infection causes toxin production by “bystander”, normal flora E. coli. Or, that the phage itself is, or carries, the toxin.

A more likely reason/hypothesis is that the antibiotics cause the bacteria to lyse which releases lots of endotoxin/LPS (as well as other Toll-like receptor tickeling molecules) which could cause significant inflammation and intestinal damage. I guess that it is also possible that pre-formed toxin stored within the bacteria could also be released. That is a problem with cholera but I don’t know about O157.

DDS
#19 PhysioProf
September 17, 2006

“…phage, which carry the toxin.”

If the toxin is encoded by a phage, I wonder if a treatment could be based on ingesting a different phage that could outcompete the toxin-encoding phage for the transcriptional and protein-synthesis machinery within the O157 bacteria?
#20 DDS
September 17, 2006

“If the toxin is encoded by a phage, I wonder if a treatment could be based on ingesting a different phage that could outcompete the toxin-encoding phage for the transcriptional and protein-synthesis machinery within the O157 bacteria?”
Physio Prof.

The major problem with that strategy is that expression of the toxin gene only requires a very small amount of the transcriptional and translational machinery. You might be able to engineer a counteracting phage that encodes a potent repressor of toxin gene expression. The major problem is getting it to the infecting O157.

DDS
#21 KevinC
September 17, 2006

Most irragation water in Yuma is not sanitized in any way. It is water streight out of the Colorodo. I just irrigated my yard with it today.

This was from the summer greens fields in central Ca and I do not know as much about them. I bet that at least some if not most of the water is ground water and thus easily polluted. Well water can be contaminated too and the ground it is dumped on can also be contaminated.

My culprut is the change of seasons. The workers in these packing plants often work half the year in Ca and the other half in Az and this is about the change over time. Just a theory but if I was investigating I do not think I would not overlook it.
#22 KevinC
September 17, 2006

Urgh. . . . would overlook it. To much sun!
#23 Stephen
September 18, 2006

Apparently, U-tube has a Popeye clip run backwards to celebrate the event.
#24 Tara C. Smith
September 18, 2006

The phage certainly carry the toxin gene but I don’t think there is any evidence that release of a phage during a human infection causes toxin production by “bystander”, normal flora E. coli. Or, that the phage itself is, or carries, the toxin.

A more likely reason/hypothesis is that the antibiotics cause the bacteria to lyse which releases lots of endotoxin/LPS (as well as other Toll-like receptor tickeling molecules) which could cause significant inflammation and intestinal damage. I guess that it is also possible that pre-formed toxin stored within the bacteria could also be released. That is a problem with cholera but I don’t know about O157.

Hmm. Well, Carl tells and this review seems to suggest that the jury’s still out on exactly how antibiotics induce damage. Interesting…
#25 Jen in Austin
September 18, 2006

Tara, you asked if irradiation would help. My guess is that it would. In a previous life I worked in a meat packing facility (sausages – weiners, bologna, etc.). Our biggest fear there was not E. Coli, but Listeria.

The cleaning, sanitizing, and testing were never-ending, because we had a constant influx of raw meat coming in the door every day. At one point, my boss and I had a conversation along the lines of “there’s gotta be a better way.” He assured me that there was and pointed me to some company research that showed that irradiating meat on its way to the processing areas would virtually eliminate any pathogens in the meat (by far the likeliest source of contamination). The US stopped irradiating meat years ago because some folks got a little upset at the idea – there are always those who don’t know the difference between irradiated food and radioactive food.

Anyway, I don’t see why irradiation wouldn’t work for produce.
#26 DDS
September 19, 2006

Tara,
I read the article you linked to and I found it quite confusing and not particularly well-written. My main conclusion from it was that antibiotics might or might not be useful for treating EHEC. Which is because, as they state, “the lack of large randomized double-blind, placebo-controlled trials makes it difficult to draw conclusions concerning the question whether antibiotics are beneficial or detrimental as treatment of patients with E. coli O157:H7 infection. ”

My main conclusion from the Lancet article cited by Carl was that antibiotic treatment is contraindicated because, by the time symptoms start, the disease is too far along for antibotics to help much. In fact the treatment is very similar to the recommended treatment fo Cholera.

The article did cite a one fairly convincing paper (http://www.cdc.gov/ncidod/EID/vol6no5/kimmett.htm#6) that suggests that, in vitro, many antibiotics (Ofloxacin being the most potent) can dramatically induce (140X!)Stx expression. I wasn’t as convinced that this was due to SOS or phage induction; the kinetics seemed a little slow for that. And of course whether this happens in vivo or not is a very different question.

I guess that leaves me in the mechanism-unclear-but-if-it doesn’t-help-and-could-hurt-don’t-use-it camp.

It still surprises me how many safety/efficacy studies have not been done for most antibiotics. If it works for disease X it must work for disease Y.

DDS
#27 kral
April 25, 2008

If the toxin is encoded by a phage, I wonder if a treatment could be based on ingesting a different phage that could outcompete the toxin-encoding phage for the transcriptional and protein-synthesis machinery within the O157 bacteria?
#28 stor perde
January 24, 2009

stor perdeler
ahşap stor perde ve fiyatları
#29 perde
February 13, 2009

perde almak için süper adres
#30 perde
April 1, 2012

Popeye ate the canned stuff, so he was in danger from botulism, not E. coli. Maybe that’s why my mom cooked all veggies to a mush!!