Gene Study Sheds Light on Deadly German E. Coli Strain

Scientists caution against use of certain antibiotics in the treatment of this infection

WEDNESDAY, July 27, 2011 (HealthDay News) -- Scientists who sequenced the genetic structure of the E. coli strain that caused the deadly food poisoning outbreak in Germany that began in May say their findings could help fight the deadly bug.

Their paper was published online July 27 in the New England Journal of Medicine.

"This research gives us insights into the reasons why this particular strain of E. coli is so virulent, allows us to hypothesize about the evolution of this bacterium and provides clinically relevant information about the treatment of this infection," senior author Dr. Matthew Waldor, a researcher at Brigham and Women's Hospital in Boston, a professor of medicine at Harvard Medical School, and an investigator of the Howard Hughes Medical Institute, said in a hospital news release.

Waldor and his colleagues found that the O104:H4 outbreak strain is different from other O104:H4 strains of E. coli in a number of ways, including having a distinct set of virulence and antibiotic resistance factors. They also found that the outbreak strain also has genes encoding Shiga toxin 2 (Stx2) and the production of the Stx2 gene was increased by certain antibiotics, including ciprofloxacin.

"Based on our understanding of the genetic profile of this E. coli strain, we would suggest caution in the use of certain antibiotics to treat these infections," Waldor said.

"This analysis also emphasizes the importance of the exchange of DNA between bacteria in the emergence of new pathogens. There is evidence that the outbreak strain acquired many genes by horizontal genetic exchange, which means that bacteria gave DNA not only to the bacteria that they reproduce, but also to neighboring bacteria."

More than 4,000 people in Germany and other countries were sickened since May, when the outbreak began. They included several hundred people who developed a serious complication that can lead to kidney failure. At least 53 people died, the Associated Press reported.

The outbreak was traced to a batch of fenugreek seeds from Egypt. The seeds are sometimes used as a spice in cooking, and fenugreek sprouts are used in salads, the news service said.

More information

The American Academy of Family Physicians has more about E. coli infections.

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