Magazine article Science News

Do Bacteria Swap Genes in Deadly Game?

Magazine article Science News

Do Bacteria Swap Genes in Deadly Game?

Article excerpt

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, scientist 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.

James B. Kaper, who developers bacterial vaccines at the University of Maryland School of Medicine in Baltimore, asserts that the findings will lead to vaccines and new diagnostic techniques for harmful E. coli infection. The new data also "will provide tremendous insights into this fundamental question of how a pathogen becomes a pathogen."

Unlike most of the E. coli in the gut, the virulent strain O157:H7 has been responsible during recent decades for increasing numbers of deaths worldwide. Some of its genes enable it to better survive stomach acids and cling to instentinal walls. Others make it produce one toxin that causes bleeding lesions in the digestive tract and another, the Shiga toxin, that leads to kidney failure and even death. …

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