(RxWiki News) Scientists have finally discovered an explanation for the greater virulence of the deadly strain of E. Coli that swept through Germany recently sickening thousands.
A study revealed that the rare O104:H4 strain responsible for the outbreak is a clone that combines the virulence potentials of two different pathogens—the Shiga toxin producing ability of enterohemorrhagic E. coli and the adherence abilities of enteroaggregative E. coli.
This may explain its greater virulence and the unusually high number of infections that resulted in severe kidney complications or death.
"The source of the E.. Coli outbreak may never be known."
The findings have been published in The Lancet: Infectious Diseases and could have implications for disease reporting and detection and food safety.
Most infected with the E. Coli strain caused by the Shiga toxin completely recover with fewer than 10 percent developing serious complications. About 1,000 cases are reported each year in Germany while about 60 cases of the enteroaggregative E. Coli are reported each year. By June 20, the more virulent strain that combined the two had infected 2,684 with 810 becoming infected with the more serious complication that include kidney failure.
Helge Karch from the University of Münster investigated the virulence profiles of the O104:H4 strain by analyzing 80 bacteria samples from patients in the outbreak that recovered between May 23 and June 2, 2011.
The samples were tested for the presence of Shiga-toxin-producing E. coli virulence genes but also for virulence genes of other intestinal pathogenic E. coli. All samples were also tested for underlying characteristics, ability to adhere to cells similar to those that line the gut, and antibiotic susceptibility.
It addition to discovering the blended pathogens, the recent virulent strain was antibiotic resistant. The researchers were unable to offer an explanation as to why the pathogens blended to create the more virulent strain.