Understanding E. coli Infection and HUS

Escherichia coli, commonly referred to as E. coli, is a bacterium that is the cause of several types of infections. "E. coli bacteria are part of the normal intestinal flora in all animals and usually reside harmlessly in the colon; however, specific strains of these organisms are able to cause disease through the production of various virulence factors," says Tina Q. Tan, MD, Associate Professor of Pediatrics, Feinberg School of Medicine at Northwestern University.

Modes of transmission of the E. coli bacteria are, "through food or water contaminated by animal or human feces, or by contact with animals or humans infected with or carrying the strain in the bowel. It can be spread from person to person," explains Dr. Michael J. Muszynski, MD, FAAP, Dean, Professor of Clinical Sciences, Florida State University College of Medicine, Orlando campus.

Several strains of E. coli bacteria produce powerful toxins that cause bloody diarrhea, and all of the victims diagnosed in Central Florida were infected by a specific strain of E. coli bacteria called O157:H7. "In the United States, E. coli bacteria O157:H7 is most commonly shed in the feces of cattle, or found in farm animals like pigs, sheep, deer, rabbits and others," explains Dr. Muszynski.

Animals on farms across the country, as well as those at fairs are not regularly tested for the O157:H7 E. coli bacteria, basically because inspectors are only on the lookout for illnesses that could harm the animals themselves. An animal with this particular strain of E. coli displays no symptoms, and does not get sick. Due to this fact, researchers in a 2002 study published in the New England Journal of Medicine recommend that all cattle/livestock be handled as if they were infected. They also advise the general public to approach with caution petting zoos and other animal exhibitions at fairs.

Signs and symptoms of E. coli bacterial infection vary on a case-by-case basis. "Infection may first manifest as diarrhea and end right there. However, most cases begin with diarrhea that progresses and becomes bloody and often contains mucus. Abdominal pain is common and can be quite distressing to the patient. Nausea and vomiting occur in half of the patients; fever occurs in less than one third of cases," says Dr. Muszynski.

Unfortunately, no one is immune from becoming infected with E. coli, though infants, young children, elderly, and persons with weak immune systems are at the highest risk for infection. To confirm a diagnosis of E.coli bacterial infection, cultures from the, "blood, urine, stool or other body fluids will be taken," says Dr. Tan, also Infectious Disease Attending and Co-Director of the Pediatric Travel Medicine Clinic at Children's Memorial Hospital in Chicago, Illinois. She explains that to treat someone with an E. coli bacterial infection, the medications are dependent upon the type of infection that the person has. "In most cases, antibiotics are used to treat the infection, although this is not true in patients with diarrheal disease. Depending on the type of strain of E.coli a person has, antibiotic therapy and antimotility agents may actually make the patient's condition worse. So for those with diarrheal disease, in most cases, supportive care alone is the mainstay of therapy."