This undated handout picture released on May 30, 2011 by the German Robert Koch-Institut (RKI) shows an electron-microscopical photo of enterohaemorrhagic E. coli bacteria (EHEC). Germany said on May 29, 2011 it was pulling out all the stops to locate the exact source of an outbreak of E. coli bacteria poisoning blamed for 10 deaths, which authorities suspect may have originated in Spain.