Scanning electron micrograph of Escherichia coli, grown in culture and adhered to a cover slip. Credit: Rocky Mountain Laboratories, NIAID, NIH
Escherichia coli is the type of bacterium most often used as a host in genetic engineering because its genes are well understood. The normal environment of E. coli is the intestines of humans and animals.
E. coli infections
Although most types of E. coli are harmless, some can cause sickness and diarrhea. One type causes travelers' diarrhea. The worst type of E. coli causes bloody diarrhea, and can sometimes cause kidney failure and even death. These problems are most likely to occur in children and in adults with weak immune systems.
E. coli infections result from eating foods containing the bacteria. To help avoid food poisoning and prevent infection, food should be handled safely. Meat should be cooked well, fruits and vegetables washed before eating or cooking them, and unpasteurized milk and juices avoided. Infection is also possible by swallowing water in a swimming pool contaminated with human waste.