The diverse totality of microorganisms regularly found on and in the human body is collectively referred to as the human microbiota or microbial flora, with the largest microbial community in the body residing in the large intestine, or colon. Bacteria comprise most of the normal microbial flora, with fungi and protozoa making up a smaller contribution. Investigators have determined that any loss of health or fitness of microbial flora can be detrimental to the body, resulting in immunological dysfunction and disease. For example, individuals with chronic intestinal diseases—including inflammatory bowel disease, Crohn's disease, and ulcerative colitis—are subject to intestinal inflammation and mucosal damage, leading to losses of the intestine's beneficial flora. To restore normal intestinal function and repair tissue damage, treatment typically involves the use of antibiotics to kill harmful intestinal bacteria that may access the bloodstream. Concomitantly, these antibiotics also destroy some beneficial bacterial components of the intestine's microbial flora (previously diminished by disease-borne inflammation and tissue damage); however, the antibiotics do not affect the small percentage of fungal organisms in the microbiota. Thus, microbial fungi have opportunities to dominate mucosal niches of the intestine. See also: Antibiotic; Bacteria; Colon; Fungi; Gastrointestinal tract disorders; Human microbiota; Immune response in inflammatory bowel disease; Inflammation; Inflammatory bowel disease; Intestine; Microbiology; Microbiome