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Introduction
Escherichia coli (E. coli) is a coliform rod-shaped, Gram-negative, facultative, non-spore forming bacterium of the genus Escherichia and family Enterobacteriaceae, which includes over 53 genera and 210 species (Jenkins et al., 2017; Tenaillon et al., 2010). According to a study on drug resistances it is predicted that ten million people may die from antibiotic-resistant diseases each year by 2050 if no precautions are taken to tackle the issue, among that more than three million will lose their lives to one bacterial infection by antibiotic resistant E. coli ( O’Neill J., 2016). The E. coli strains are considered as one of the few microbes that have the skill to be adapted to numerous biofunctions. These bacteria can colonize the healthy intestinal tract of several mammals including humans. They are used as an important bio-tool in several biotechnological applications. Furthermore, they have virulence factors which cause numerous diseases in humans and animals, and affect a wide range of bio-cellular processes (Kaper et al., 2004). Although E. coli strains inhabit the gastrointestinal tract of healthy humans, it is considered as one of the most pathogenic microorganisms isolated from humans. E. coli is a very versatile bacterium that can modify easily from one bio-activity to another. Highly variable mutation rates have been reported in commensal and pathogenic E. coli strains (Matic et al., 1997).
Some strains of E. coli cause infections in the urinary, intestinal, and respiratory tracts along with other diseases. The sources of pathogenic E. coli strains include contaminated water and food, and it may be transmitted through direct contact with infected people and animals or non-direct contact. Pathogenic E. coli strains may cause enteric/diarrheal illness, urinary tract diseases (UTDs) or sepsis/meningitis (Kaper et al., 2004). According to the Centers for Disease Control and Prevention (CDC) (https://www.cdc.gov/ecoli/general/index.html, December 1, 2014), pathogenic E. coli strains can be classified into six pathotypic strains as follows: Shiga toxin-producing E. coli (STEC), enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), enteroaggregative E. coli (EAEC), enter invasive E. coli (EIEC), and diffusely adherent E. coli (DAEC). Illnesses resulting from bacterial infections caused by pathogenic E. coli strains involve diarrhea, inflammation of the kidney (pyelonephritis), inflammation of the colon (dysentery), and hemolytic-uremic syndrome. Extreme response to such infections may...