Nurses tend to a patient with the enterohaemorrhagic E. coli (EHEC) in the intensive care unit in the northern German city of Luebeck on June 7, 2011. The source of the killer bacteria remained elusive after Germany announced that initial tests on suspected organic sprouts had proved negative and the outbreak's death toll grew to 23. Some 2,000 people have become ill across Europe from the enterohaemorrhagic E. coli (EHEC) outbreak which has affected 12 countries. AFP PHOTO / MARKUS SCHOLZ GERMANY OUT