Food Safety: Why Do People Keep Getting E Coli?

The New York Times is carrying a high-profile article about a woman who was paralyzed from an e. coli infection.  Reading the article I once again wondered what I had so many times before: why do people keep getting sick from hamburger?  Aren't we all cooking our hamburgers pretty well these days? Granted the manufacturer is absolutely the one to blame for putting the e. coli in the burger in the first place - but don't consumers carry some of the responsibility for cooking their meat properly?

The first thing I found is that not all e. coli infections are created equal.  As many people know, e. coli is one of the most common bacteria we encounter on a day to day basis.  E. coli populate the intestines of most warm blooded animals, ourselves included.  Various strains of e. coli create vitamin K for us, fight off harmful bacteria, and generally just hang out without causing any problems.

However, Stephanie Smith, the subject of the article, had the misfortune to encounter a strain of e. coli called serotype O157:H7. It's a shame this strain of e. coli hasn't been given a snappy name by the media, because it's the one that causes the real problems.  O157:H7 was first discovered in the early 1980s in conjunction with outbreaks of food borne illness, which was eventually traced back to hamburger.

O157:H7 is very virulent, easily hopping from one host to another.  It can be present in the intestines of healthy cows and pigs, which serve as a vector for the bacteria.  O157:H7 can live on the outside of a cow's udder and be passed to her milk (where it is killed by the pasteurization process - but can thrive in unpasteurized milk).  Unfortunately, according to Michael Pollan in "The Omnivore's Dilemma," one side effect of fattening cattle on grain at the last stage of their lives is to increase the amount of e. coli bacteria found in their systems.

O157:H7 is much more common in hamburger than in proper cuts of meat.  Because the bacteria restricts itself to the cow's intestines, it does not infuse itself into cuts of meat.  It gets into meat only when infected feces contaminate the outside of the meat - which can happen easily in the slaughterhouse environment.  

Cooking beef will indeed kill O157:H7.  Cuts of meat are safer than ground beef, because it is far easier to properly cook the outside of a cut of meat than it is to cook every single atom of ground beef.  O157:H7 contamination will only be found on the outside of a cut of meat, but it will be ground up and suffused throughout ground beef.

The bad news is that just because O157:H7 has been killed, that doesn't mean that you are safe.  The bacteria can leave behind toxins which are not destroyed in the cooking process, and can easily make you sick.  Furthermore, the New York Times did some testing and found that the bacteria can thrive elsewhere in your kitchen.  They found that just setting down the tray of meat left behind enough bacteria to cause illness within a few hours at room temperature.

How best, then, to prevent O157:H7 illness?  Cook your meats to the proper temperatures.  Use a meat thermometer.  Avoid unpasteurized juice and milk.   Stick to local meat producers and "real" butchers whenever possible.  Buy a cut of beef, then ask the butcher to grind it for you.