TAXONOMY: cellular organisms -> Bacteria -> Proteobacteria -> Gammaproteobacteria -> Enterobacteriales
The 'Enterobacteriales' are an order of Gram-negative bacteria that includes only one family which is the Enterobacteriaceae, a family of gram-negative, facultatively anaerobic, rod-shaped bacteria, usually motile, made up of saprophytes and plant and animal parasites of worldwide distribution, found in soil, water, and plants and in animals from insects to humans. In humans, disease is produced by both invasive action and production of toxin. Species not normally associated with disease are often opportunistic pathogens. Enterobacteriaceae have been responsible for as many as half of the nosocomial infections reported annually in the United States, most frequently by species of Escherichia, Klebsiella, Enterobacter, Proteus, Providencia, and Serratia.