E coli outbreak linked to tainted bean sprouts

By Dr. Ananya Mandal, MDJun 5 2011

It has been announced by German officials late Sunday that domestically grown bean sprouts may be the source of the Escherichia coli (E. coli) outbreak that has killed 22 people and sickened at least 1,600. All but one of the deaths occurred in Germany, the source of the entero haemorrhagic E. coli (EHEC) outbreak that has affected 12 countries. The other victim died in Sweden.

The health authorities is Germany have not yet completed testing to determine whether the E. coli strain traced to a northern German bean-sprout farm is a match to the deadly cases that have affected people from 12 countries. But agriculture ministry officials in the German state of Lower Saxony said they had found links between an area bean-sprout supplier and at least five restaurants where diners were later found to have been infected with the deadly bacterial strain. They added that a bean-sprout firm's employee had become ill with an E. coli infection, and the warm, damp conditions for growing bean sprouts are perfect for bacteria.

Gert Hahne, spokesman for the ministry said, “This all, in combination with the different clues, makes the chances of this [supplier] being the source pretty high.” For now the bean-sprout supplier, located in southern Lower Saxony, has been shut down and its products have been recalled. The E. coli-infected sprouts are undergoing tests to determine if they might be one of or the only source of the outbreak.

At a news conference in Hamburg on Sunday, Reinhard Burger, president of the federal health ministry-funded Robert Koch Institute, said it is too early to say if the bean sprouts are responsible, but added that government authorities are tracking every possible clue. He added that of the more than 1,500 Germans infected with E. coli, 627 have developed a severe complication that wreaks havoc with the nervous system and shuts down the kidneys, an unusually high percentage for E. coli outbreaks. He warned that all people there should continue to avoid raw tomatoes, lettuce and cucumbers.

German Health Minister Daniel Bahr, who was on Sunday visiting Hamburg's Eppendorf University clinic, where many of the region's EHEC patients are being treated, has warned that the source of infection could still be active. “Food health officials are working around the clock to identify the source of the infection…But from earlier outbreaks we know that we can't always identify the source. It can't be ruled out that the source of infection is still active,” he said.

According to researchers this May outbreak is among the deadliest in modern history to involve E. coli, and involves a rare strain not seen before in a human outbreak of the bacteria. Researchers believe the strain behind the outbreak could have formed from a genetic recombination of two different E. coli bacteria, producing an unusually virulent bug, the World Health Organization said Thursday, citing preliminary genetic-sequencing data.

Meanwhile, several German scientists suggested on Sunday the outbreak could be linked to bacteria found in biogas plants. Biogas, or methane, is produced by the anaerobic digestion or fermentation of biodegradable material such as manure, sewage and green waste. “There are all sorts of bacteria which didn't exist before which are now produced in biogas fermentation tanks,” Bernt Schottdorf, a medical analyst said. “They crossbreed and mix with one another - what goes on precisely hasn't really been studied,” he said, adding that 80 per cent of the production waste finds its way back on to fields as fertilizer. Ernst Guenther Hellwig, head of the veterinary and agriculture academy in Horstmar-Leer, added that, because it had rained very little in the spring, it was possible such fertilizers had not been washed off growing plants. “Dangerous bacteria could be brought on to the fields this way and could contaminate vegetables,” he said.

Mr. Burger added, “We're still looking at their supplier list and trying to find connections.” Most of the infections have been tied to northern Germany, and the city of Hamburg saw the first cases of the deadly strain.

In the US the number of suspected cases remained at four on Sunday, a Centers for Disease Control and Prevention spokeswoman said.

“Right now there have been no reports of any additional suspected cases” in the United States, CDC spokeswoman Lola Russell said. All four U.S. patients recently visited Hamburg, Germany, officials said.

There are no indications the U.S. food supply has been tainted by E.coli, U.S. Food and Drug Administration spokesman Siobhan DeLancey said on Sunday. However, as a safety precaution, the FDA said it was conducting increased surveillance of fresh tomatoes, cucumbers, lettuce and raw salads imported from areas of concern. But officials said countries in the European Union are not a significant source of fresh produce for the United States.