E. coli bacteria were discovered in the human colon in 1885 by German bacteriologist Theodor Escherich. Dr. Escherich also showed that certain strains of the bacteria were responsible for infant diarrhea and gastroenteritis – an important public health discovery.

E. coli O157:H7 is one of hundreds of strains of the bacterium Escherichia coli. The combination of letters and numbers in the name of E. coli O157:H7 refers to the specific markers found on the bacterium’s surface; these letters and numbers distinguish the dangerous O157:H7 variety from other types of E. coli.

The virulence of E. coli O157:H7 is a result of its ability to produce Shiga-like toxins, or verotoxins. Shiga-like toxins inhibit protein synthesis in eukaryotic cells and play a role in hemorrhagic colitis and hemolytic uremic syndrome by causing damage to endothelial cells in the kidneys, pancreas, brain, and other organs, thus inhibiting those organs’ ability to function.