A large and deadly outbreak of food poisoning in Europe has been linked to a “super-toxic” new strain of Escherichia coli bacteria. The outbreak seems to be linked to the consumption of fresh vegetables. Yet whenever I hear of an outbreak of E. coli, I wonder, “Where’s the poop?”
The natural habitat of E. coli is inside the intestines of warm-blooded animals. Since vegetables are not warm-blooded, and they have no intestines, how can they be a source of E. coli? The answer, of course, is that E. coli can survive outside of their host for a short time. That’s how they can spread from one host to another. It’s also why “coliform bacteria counts” are used to evaluate how badly a body of water has been contaminated with raw sewage. If vegetables are spreading E. coli, it’s because they’ve been contaminated by the droppings of a warm-blooded animal.
Some strains of E. coli are normal inhabitants of the human intestinal tract. However, if you find ordinary E. coli you might also find other, more dangerous bacteria and viruses that can spread from one person to another by the “fecal-oral route,” which is when people swallow something that has been contaminated by someone else’s poop.
The E. coli strains that are commonly found inside human intestines have learned to live inside a human host without causing any trouble under normal circumstances. Unfortunately, the E. coli that normally live in the intestines of other kinds of animals, such as cattle, can make people really sick. Even more unfortunately, E. coli bacteria can swap genes with other strains of E. coli, and even with unrelated bacteria. Thus, bacteria can learn bad habits from each other. They may learn how to make a deadly new toxin, or how to resist antibiotics.
If history is any guide, this outbreak of deadly E. coli food poisoning resulted from the use of fresh animal manure to fertilize vegetables. Fresh manure is unsanitary. It should never be allowed anywhere near food that will be eaten raw!
Update, 6/6: At first, health officials suspected that the E. coli outbreak resulted from raw vegetables from Spain. Then, suspicion shifted to raw sprouts from an organic farm in Germany. Bean and alfalfa sprouts are a common source of Salmonella and E. coli food poisoning. That’s because they are often grown in moist conditions at a temperature that approximates human body temperature. However, sprouts aren’t fertilized and therefore should not have come into contact with cow manure. The E. coli would therefore have had to come from contaminated seeds, from contaminated water, or from one of the workers. The owner of the German sprout farm insists that there were no animals or animal products on site. It’s possible, but somewhat unlikely, for one of the workers to be carrying a dangerous bovine strain of E. coli. So far, health authorities have been unable to find any evidence of the E. coli strain in the sprouts or at the sprout producer’s premises. Of course, those tests can’t prove that the E. coli strain was never there. It’s possible that the source of the outbreak may never be known for sure.
Photo by Randy Heinitz