To find out how this strain of the intestinal bug proved so lethal, researchers led by Dr. Helge Karch from the University of Munster studied 80 samples of the bacteria from affected patients. They tested the samples for shiga toxin-producing E. coli and also for virulence genes of other types of E. coli.
That's when they uncovered the strain's use of shiga toxin and its propensity to adhere tightly to cells in the digestive tract. This tight bond between the bacteria and the intestinal cells " might facilitate systemic absorption of shiga toxin," the authors wrote, upping the odds that a patient might progress to the sometimes deadly hemolytic uremic syndrome.
The strain was also resistant to common antibiotics, specifically penicillins and cephalosporins. Luckily, it was susceptible to another class of antibiotics called carbapenems.
According to the New England Journal of Medicine study, severe cases involving the hemolytic uremic syndrome have occurred mainly among adults, predominantly women. In one medical center in Hamburg, 12 of 59 patients infected with the O104:H4 strain went on to develop the sometimes form of deadly kidney failure, according to a team led by Christina Frank, of Berlin's Robert Koch Institute.
For their part, the authors of the Lancet study believe that the emergence of the new strain "tragically shows " how E. coli can change and "have serious consequences for infected people."
One outside expert agreed. Infectious disease expert Dr. Marc Siegel, an associate professor of medicine at New York University in New York City, said that "in this case the bug itself is more virulent and more transmissible."
This is just part of how the bacterium develops to survive, Siegel explained. And these changes may well affect other strains of E. coli. "These bugs are becoming more virulent," he said.
One culprit, according to Siegel, is the ov
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