E. coli bacteria have a single cell arrangement, according to Schenectady County Community College. E. coli is a gram-negative bacillus bacteria that can live with or without oxygen. Escherichia coli is normally found amongst the gut flora of the human intestinal tract and is non-pathogenic.
Although E. coli is normally not harmful to healthy people, there are a few virulent strains that can cause diarrhea, abdominal cramps and vomiting, according to the Mayo Clinic. As explained by Schenectady County Community College, Enterotoxigenic coli, Enteropathogenic coli, Enterohemorrhagic coli and Enterohemorrhagic coli are four pathogenic strains that are transmitted by a fecal-oral route.