But what makes this particular strain so different from those known from previous outbreaks of foodborne illness?

"O104:H4 may be an interesting case of a microorganism acquiring genetic material from another bacterium," said Scott Wilbur, a postdoctoral researcher in the lab of V. K. Viswanathan, an assistant professor in the UA's Department of Veterinary Science and Microbiology who specializes in studying EHEC strains.

Wilbur added that most related strains do not cause serious disease in humans, but the strain in Germany has acquired a virulence gene that enables it to make Shiga-toxin. This small addition of genetic material resulted in the transformation of a non-pathogenic strain of E. coli into a strain that causes bloody diarrhea, and in some cases, HUS.

O104:H4 belongs to a subgroup of E. coli that usually cause symptoms only in people with a compromised immune system. This strain has also acquired resistance to some commonly used antibiotics.

"This is an example of evolution at work," said Christopher Rensing, an associate professor in the UA's Department of Soil, Water, and Environmental Science. "We tend to forget how easy it is for bacteria to get together inside the gut and exchange genetic material and acquire new traits very rapidly."

"The O104:H4 strain is one of so-called emerging pathogens, and it's coming up right now," added Sadhana Ravishankar, an assistant professor in the UA's Department of Veterinary Science and Microbiology. "Because of the bacteria's ability to constantly change, there is no one-size-fits-all solution to prevent outbreaks from happening."

Increasing food safety and reducing the risk of outbreaks is Ravishankar's main research focus. Although her studies have concentrated on O157:H7, a different EHEC strain that was responsible for major foodborne outbreaks in the U.S., Ravishankar expects that its counterpart in Germany would react similarly to the preventive measures her team is investigating.

Together with Viswanathan, she just submitted a grant proposal to find new methods of increasing food safety in the context of known EHEC strains. One of the goals is to investigate how bacteria attach to the surfaces of leafy greens and whether they are able to get inside the plants.

"If they can, we have to ask whether the existing treatments are enough and whether we have to add measures," Ravishankar said.