Escherichia Coli Infections
An Intestinal Bacteria Causing Multiple Illnesses
E. coli is often associated with serious food poisoning and other conditions. What exactly can this bacteria do?
Escherichia coli, also known as E. coli, may pop up in the media when it causes major outbreaks, such as those involving undercooked hamburger patties at Jack in the Box restaurants in 1993 and spinach in late 2006. It lives inside the intestinal tract of humans and animals, but it is capable of spreading to others. E. coli infections can sometimes be severe. However, they can be prevented as well.
Characteristics and Habitat
E. coli is a type of gram-negative bacteria, defined by a cell membrane surrounded by a peptidoglycan cell wall that is in turn surrounded by another membrane. This particular species of bacteria is facultatively anaerobic, capable of performing metabolism with oxygen (aerobic) or without oxygen (anaerobic). These bacteria are shaped as elongated rods existing alone or in pairs. They possess three types of antigens - O, K, and H - that serve as the basis for serotyping the many forms of E. coli.
E. coli inhabits the large intestine of humans and some animals without causing any harm to the host. It leaves the body through fecal matter. From there, it can be introduced into another host through various unhygienic means. The type of infection that occurs and its severity depend on where it enters the body and what type of E. coli it is.
Intestinal Infections
E. coli is commonly introduced into humans through the oral route, causing intestinal (enteric) infections. Many people fear the type of illness that occurs with enterohemorrhagic E. coli (EHEC), of which serotype O157:H7 is a notorious example. This strain is capable of producing bloody diarrhea and abdominal cramping with powerful toxins. Antibiotics for this type of infection may not shorten the disease course. The treatment is mainly supportive, addressing dehydration and other problems as they come up. A small percentage of infections with EHEC, mostly involving children and the elderly, can lead to a potentially fatal complication called hemolytic uremic syndrome, which consists of anemia from destruction of red blood cells, low platelets, and kidney failure and requires blood transfusions and dialysis.
Not all enteric infections by E. coli occur this way. Besides EHEC, there is also enterotoxigenic E. coli (ETEC). This group produces a toxin that stimulates the small intestine to secrete more water into the intestinal space. People infected with ETEC experience a diarrhea that is watery but generally not bloody. This can happen with travelers who drink contaminated water, often called "traveler's diarrhea." Other types of E. coli include enteropathogenic E. coli (EPEC) causing infant diarrhea and enteroinvasive E. coli (EIEC) causing dysentery with stool containing mucus.
Extraintestinal Infections
Infections by E. coli outside the intestinal tract can occur in a variety of places. For example, E. coli causes urinary tract infections in women because of the proximity of the short urethra from the anus. It can also be transmitted from a pregnant woman to a newborn through delivery and cause meningitis in the baby, specifically with E. coli K1. Other possible infections with E. coli include pneumonia, soft tissue infections, and several others, all involving some means of introducing this intestinal bacteria to the site of infection.
Transmission and Prevention
As a result of uncleanliness, E. coli spreads from feces to multiple external environments and then into another individual. This can happen through undercooked food, contaminated water, or simply with dirty hands. Even with government policies, like mandatory handwashing for restaurant workers and safety practices for meatpacking plants, individuals should still take basic precautions. Raw meat should not come into contact with surfaces and utensils intended for other foods. Undercooked meat at restaurants should be sent back for recooking. Most importantly, people should wash their hands after using the bathroom, changing diapers, or performing other tasks involving potential contact with fecal matter. This simple but often neglected preventive measure can make a difference when everyone does their part.
References
- Centers for Disease Control and Prevention (CDC) - E. coli
- eMedicine - Escherichia coli Infections
- Food and Drug Administration (FDA) - Bad Bug Book
