In 1982, contaminated hamburger meat triggered a rash of violent illness in the United States and signaled that a bacterial friend of people had turned foe. The culprit turned out to be a virulent strain of Escherichia coli, normally a helpful resident of the lower intestine (SN: 7/22/00, p. 53).
Now, scientists from the University of Wisconsin-Madison have decoded the genome of the dangerous strain and compared it with the DNA sequence of its far more common, mild-mannered cousin (SN: 2/8/97, p. 84).
The two sequences provide hints as to how a bacterium so deadly could be the close relative of one so benign. The pathogen, the researchers assert in the Jan. 25 Nature, had picked up chunks of DNA from unrelated, infective bacteria, acquiring unpleasant traits that can send people to the hospital.