Escherichia are animal and human intestinal pathogens. Thegenus Escherichia consists of five species: E. coli, Escherichiafergusonii, Escherichia hermanii, Escherichia vulneris, and Escherichia blattae. Of these species, E. coli is the most common and mostimportant species causing infection in humans. E. coli is further subdivided into biotypes and serotypes based on O, H, and K antigens.
E. coli has been recognized as harmless commensal and also asa versatile pathogen. E. coli in humans causes a broad spectrum of diseases. It is an important cause of enteric illness, urinary tract infection (UTI), neonatal sepsis, and neonatal meningitis. Hemolytic uremic syndrome (HUS) is a serious complication of enteric infection with certain E. coli strains.