Another month, another food-borne outbreak. In the most recent E.coli news, the bug has shown up in cookie dough and, possibly, beef.  In case you've wondered what it is that makes E. coliO157:H7 so very much more dangerous than the E. coli that resides in great numbers in our bowels (I have) here's a primer. But first, a look at it under the electron microscope. Pretty, eh? (In reality it's not pink: that's a bit of artistic license.) According to the Centers for Disease Control and Prevention, there are many E. coli strains, but only some of them produce a shiga toxin. (O157:H7 is one of these.) This toxin-producing trait doesn't come from the E. coli genes — it comes, instead, from a virus that invaded the bacterium some time in the past. There are a whole class of bacteria-invading viruses, known as bacteriophages, in nature — in the Soviet Union, people used to drink bacteriophage tonics that they'd get from their doctors, in the hopes that these would fight bacterial infections. Scientists are still investigating whether some phages (as they're known for short) may work effectively as antibiotic stand-ins. The virus that directs formation of shiga toxin in E. coli isn't the kind that invades a cell, then immediately turns it to tatters while making thousands of copies of itself. Instead, the virus can sit there happily inside the bug — its DNA stitched neatly into the genome of the bacterium — steadily directing formation of t…[...]

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E. coli in cookie dough: a primer on the bug