Escherichia coli is a Gram-negative, facultative anaerobic bacterium. This rod-shaped coliform is naturally found in lower intestines of humans and many animals. It benefits the host by synthesizing vitamin K2. Most of the strains are harmless, but certain serotypes such as E. coli O157:H7 are well-known pathogenic. This particular strain is responsible in food contamination, causing symptoms like severe abdominal pains, vomiting, nausea and bloody diarrhea. E. coli O157:H7 can produce Shiga toxin that cause intestinal infection.
We can get contamination by E. coli from improper food handling. Fecal-oral route of transmission is very common as E.coli can be found in guts. People who handle the food should wash their hands properly before preparing the food. Utensils and cutting boards should also be cleaned before every use to prevent cross-contamination from uncooked food. In addition to that, E. coli can contaminate raw food and unpasteurized milk. Contaminated water that is used to wash vegetables and fruits could also possibly spread the contamination to consumers.
In May 2018, 172 people in United States were infected with the outbreak of E. coli O157:H7 strain. The source of this contamination were believed to be the romaine lettuce from Yuma, Arizona. 1 death was reported from this case.