How To Stop The Superbugs

The E. coli outbreak that started in Germany reveals how hard it is to police a global food supply — and how important, as bacteria grow more deadly

By Alice Park Monday, June 20, 2011
    • Wolfgang Rattay / Reuters

    So are the sprouts to blame? Suspicions first fell on cucumbers from Spain, then on sprouts from an organic farm in Germany- but DNA tests have not confirmed a culprit.

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    But good coordination is not always enough. No matter how strong food-safety policies are, bugs like E. coli can find their way into meat and other foods, especially fruits and vegetables such as spinach, peppers and onions. In fact, we live with certain colonies of E. coli in our gut, and the bugs are essential to helping us digest and break down food. But E. coli is notoriously promiscuous, adept at swapping genetic material not just with other strains but with other organisms as well. Crowded conditions for cattle, sheep and other livestock that can harbor colonies of E. coli provide the ideal environment for games of genetic roulette. And all of that makes the bacterium especially nimble, able to mutate easily into ever more destructive forms. The U.S. got a taste of that nightmare in 1993, when E. coli O157 caused its first significant outbreak of illness, with others to follow — principally through hamburger meat and spinach.

    The current bug, O104:H4, is even deadlier. A rare strain that in the past has caused illness in limited numbers only, O104:H4 combines a powerful toxin known as Shiga toxin with a form of bacterial glue that sticks the organism to the gut wall for up to two weeks, providing it with the perfect spot from which to release its poison. Once in our bodies, the toxin breaks down red blood cells, leading to clots and strokes, and targets kidney cells, causing a form of kidney failure known as hemolytic uremic syndrome (HUS) — and sometimes death. Some patients who develop HUS and recover may need dialysis for the rest of their lives. "In terms of the numbers of cases of HUS, what we're seeing in Germany is much bigger than anything we've seen before," says Dr. Robert Tauxe of the CDC. "That does surprise me."

    In most E. coli outbreaks, contamination starts with an infected ruminant — a cow, sheep or goat. Although it doesn't become ill, once the animal is slaughtered, the raw meat can cause illness, and people or utensils that come into contact with the raw meat can spread the contamination. Cooking contaminated meat generally kills E. coli, but increasingly, the bacteria have been showing up in produce that most people eat raw. Farmers often use manure to fertilize vegetable crops, and contaminated feces could spread the bacteria to these foods. Infected runoff from agricultural pastures could also reach crops and deposit E. coli in the roots or leaves of plants. Given that we're in the midst of the spring and summer growing season, more people are eating fresh produce, which may be a reason so many have become ill.

    And treating these people isn't easy. Antibiotics aren't always the answer, since the drugs may merely provoke the bugs and lead them to pump out even more toxin. Much of the health care patients need involves hydration with intravenous fluids and treatment of blood clots, strokes and kidney failure with the appropriate supportive therapies.

    As the number of new cases starts to abate, many countries, including the U.S., will continue to put German imports under special scrutiny. Meanwhile, individuals can take preventive action like washing their hands before and after handling raw food, thoroughly washing produce — especially the kinds eaten raw — and cooking food properly. "The tragic E. coli outbreak in Europe reminds us that investing in prevention of food-safety problems is ultimately the only way to provide the protection that consumers expect and to avoid economic and social disruption," says Dr. Elisabeth Hagen, Under Secretary for Food Safety at the U.S. Department of Agriculture. For now, the U.S. maintains a bit of an edge in this kind of preparedness, but it's an edge that could erode fast.

    Disease Detectives
    Tracing an outbreak back to its source

    1. Identifying the cases
    Once public-health officials suspect an outbreak, they start creating a profile of all possible cases. Symptoms the victims share can help point to a possible cause, in this case, E. coli. Both sick and healthy people receive questionnaires asking what they ate, where they ate and where else they've been.

    2. Targeting the source
    With questionnaire data in hand, investigators refine their search, trying to trace where the infected food came from. Which grocery stores or restaurants did the sick individuals frequent? Did they all visit a particular farm or other facility?

    3. Record search
    Investigators go to the restaurants or stores and sift through shipment records to find out the origins of the foods. Since most such businesses get shipments from various distributors, this can take days or even weeks.

    4. Narrowing the search
    Investigators go to distributors' warehouses and inspect their records and current supplies. They study packaging and try to determine which farms provided which products at the key times.

    5. At the source
    The final investigations take place on the farms where the food was grown. The teams inspect crops (including irrigation and proximity of animals to vegetable fields). They look at collection methods and facilities as well as packing methods to determine if the bacteria came from infected animals or was spread by unsanitary human handling.

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