Researchers think they now know why a particularly virulent form of E. coli that swept through northern Germany last May was so hard to trace: The germs responsible eluded detection by going into a self-induced deep sleep.
Two new studies show that when stressed, E. coli can turn off most signs of life. That’s a problem for food-safety officials because their germ-screening techniques rely on germs reproducing to establish the presence of live bacteria.
In the lab, the scientists stressed the germs by exposing them to copper. Within a few days, many of the bacteria entered the dormant state and remained that way unless the researchers removed copper from the germs’ growth medium. Antje Flieger and her colleagues describe their findings in the December Environmental Microbiology.
Once resuscitated, the germs still had all of the features needed to be infective. For example, they had retained the genes to produce their lethal toxin and to make the sticky hairlike features that foster gut attachment. “That’s why we speculate they should be active and allow infection,” Flieger says.
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