Spinach, Swine, and E. Coli E. coli O157:H7 is a strain of Escherichia coli bacterium. Unlike the other strains which are harmless, this one can cause illness with the Shiga-like toxin it produces. This subtype of the bacterium can be found in the intestines of healthy farm animals: cattle, goats, and sheep. It is distinguished from other E. coli by its specific surface markers, the abbreviation of which can be found in the name. This type of E. coli is included in a class of dangerous E. coli, called enterohemorrhagic. E. coli O157:H7 was discovered in 1982, during a severe outbreak of bloody diarrhea, associated with the consumption of contaminated hamburgers. It is negative for invasiveness, unlike other E. coli, does not produce any colonization factors, and is not hemolytic (Roberts, 2001). The contamination of bagged baby spinach with E. coli occurred because of infection of baby spinach by cattle feces that showed positive for the O157:H7 strain. As the method of this bacterium’s invasion is mostly fecal-oral, the E. coli traveled with the cattle’s feces through the water on a spinach field and this way people got infected by contaminated fresh produce that was not properly washed or thermally processed. The time between being exposed to the bacteria and becoming ill is 3-4 days. Bloody diarrhea and abdominal cramps are the main symptoms of E. coli O157:H7 affection. Sometimes the diarrhea is free of blood and there are no other symptoms visible. The fever is insignificant, and the disease lasts 5-10 days. The hemolytic uremic syndrome is one of the complications of contamination with this strain of bacteria. It is common in the elderly, as well as in children. Acute kidney failure is accompanied by the destruction of erythrocytes. This complication affects about 8 % of those infected by E. coli O157:H7. Comparing to other food-borne illnesses, for example, Campylobacter jejuni caused enteritis, which besides diarrhea is characterized by abdominal pain, high fever, the E. coli infection is not so rich in symptoms. E. coli O157:H7 outbreak in several Taco Bell restaurants was linked to contamination of lettuce, shredded cheese, and ground beef by this strain of bacteria. However lettuce is considered to be the most probable product to transfer the pathogen, as the cheese underwent the process of pasteurization, and ground beef was cooked. Pulsed-field gel electrophoresis (PFGE) subtyping is used as an epidemiological standard in the study of pathogens. This test facilitated discriminating among different strains of bacteria and therefore identifying geographically dispersed bacterial outbreaks. The procedure consists of running periodically reversed voltage through a standard gel so that each DNA band runs in the opposite direction. PFGE subtyping results for geographically dispersed cases are submitted by laboratories to a national database, and from there are compared to determine whether there is a common source. This determination is guided using PFGE subtypes. If a common infection source has been discovered, and the bacteria had been isolated from this source, subtyping allows determining, if it is an outbreak strain (Thompson, 2000). A Virus Killer