Intestinal flora, bacteria
The entirety of all intestinal microorganisms, predominantly living in the colon, constitute the intestinal flora. Most of them are bacteria of the groups Escherichia coli (E.coli), enterococcus, bacillus, or bacteroides. Pathological circumstances can shift the balance in favor of one type of germ, which causes a dysbactery. The most prominent example is the pseudomembranous colitis, caused by prescribed antibiotics, where the whole colon is being overrun with clostridium dificile.