|SEM micrograph of cluster of Escherichia coli bacteria. Each individual bacterium is oblong shaped|
Castellani & Chalmers 1919
Escherichia is a genus of Gram-negative, non-spore-forming, facultatively anaerobic, rod-shaped bacteria from the family Enterobacteriaceae. In those species which are inhabitants of the gastrointestinal tracts of warm-blooded animals, Escherichia species provide a portion of the microbially derived vitamin K for their host. A number of the species of Escherichia are pathogenic. The genus is named after Theodor Escherich, the discoverer of Escherichia coli. Physiologically, it is a facultative aerobe, meaning that it can grow happily with or without oxygen, but it cannot grow at extremes of temperature or pH nor can it degrade dangerous pollutants, photosynthesize, or do a variety of other things that interest microbiologists.
While many Escherichia are commensal members of the gut microbiota, certain strains of some species, most notably the serotypes of Escherichia coli, are human pathogens, and are the most common cause of urinary tract infections, significant sources of gastrointestinal disease, ranging from simple diarrhea to dysentery-like conditions, as well as a wide range of other pathogenic states classifiable in general as colonic escherichiosis. While E. coli is responsible for the vast majority of Escherichia-related pathogenesis, other members of the genus have also been implicated in human disease.Escherichia are associated with the imbalance of microbiota of the lower reproductive tract of women. These species are associated with inflammation.