Escherichia coli consists of numerous strains of Gram-negative, anaerobic, rod-shaped bacteria. E. coli are considered to be both a good and a bad bacteria. E. coli are found in the gastrointestinal system of normal, healthy people, animals and birds where they constitute around 0.1% of the gut flora; however some strains are pathogenic and cause harm. Pathogenic E. coli are known to cause a number of different diseases in poultry, and are associated with the onset of several significant viral, fungal, parasitic and bacterial diseases in poultry of all ages, and humans. E. coli are commonly found in fecal matter.