BERLIN - A large and unprecedented outbreak of bacterial infections linked to contaminated vegetables claimed two more lives in Europe on Tuesday, driving the death toll to 16. The number of sick rose to more than 1,150 people in at least eight nations.

Nearly 400 people in Germany were battling a potentially fatal version of the infection that attacks the kidneys and kills up to 5 percent of patients. A U.S. expert said doctors had never seen so many cases of the condition, hemolytic uremic syndrome, tied to a foodborne outbreak.

The mystery deepened with new evidence that German vegetables may have been contaminated by at least two strains of enterohaemorrhagic E.coli, or EHEC.

Authorities in Hamburg said last week that they had detected EHEC on four cucumbers in a market in the northern German city, three imported from Spain and the fourth of unclear origin.

On Tuesday, however, officials said they had found a slightly different type of EHEC on the cucumbers than the strain detected in the feces of sick people in Germany. That means those cucumbers did not cause the outbreak but posed a health risk nonetheless, the German officials said.

Spain's agriculture minister, Rosa Aguilar, seized on the find as evidence that "our cucumbers are not responsible for the situation."

The northern state of Schleswig-Holstein, which neighbors Hamburg and is one of the worst affected, said that tests on 141 samples of food including cucumbers, tomatoes, milk products, zucchini, and poultry had found no EHEC.

E. coli is found in large quantities in the digestive systems of mammals and has been responsible for a large number of food-contamination outbreaks in a variety of countries. In most cases, it causes nonlethal stomach ailments.

But EHEC causes more severe symptoms, ranging from bloody diarrhea to the rare hemolytic uremic syndrome. In Germany, at least 373 people have come down with the syndrome, or HUS, in which E. coli infection attacks the kidneys, sometimes causing seizures and strokes.

"The idea of an outbreak of over 300 hemolytic uremic syndrome cases is absolutely extraordinary," said Robert Tauxe, deputy director of foodborne, waterborne and environmental diseases at the U.S. Centers for Disease Control.