ABSTRACT
Escherichia coli is a Gram-negative, rod-shaped bacterium that constitutes 0.1%–5% of gut microbiota in warm-blooded mammals and humans. Most E. coli strains colonize the gastrointestinal tract of warm-blooded animals including humans as harmless commensal microorganisms. However, a small number of strains show the potential to cause both intestinal and extraintestinal infections in the human population. E. coli is a Gram-negative, rod-shaped, motile, non-spore-forming, facultatively anaerobic bacillus of 1–2 μm in length and 0.35–0.6 μm in width. Forming part of the natural flora of animals including humans as well as birds, reptiles, and fish, E. coli frequently contaminates soil, water source, and plants. Prevention of E. coli infection involves personal hygiene; proper cleaning, processing, and cooking of fruits, vegetables, and meat; avoidance of touching/petting farm animals; and provision of chlorinated drinking water. Plasmids and transposons represent the most common tools for genetic manipulation of E. coli and indeed other bacteria.
