E. COLI

E. coli



E. coli

Introduction

E. coli is a bacterium that is found in the intestinal tract of humans and animals. Not all E. Coli bacteria make people ill. The E. Coli 157:H7 bacteria are the specific bacteria that are responsible for most of the illness related to the consumption of ground beef. (Pharmacopeia 2001)

Symptoms of E. coli foodborne illness start about a week after eating contaminated food and begin suddenly with severe abdominal cramps progressing within a few hours to watery diarrhea. The watery diarrhea lasts about 24 hours, then bright red bloody stools begin. The bloody diarrhea lasts 2 to 5 days. Fever is usually absent or low grade. Nausea and vomiting may be present. Using anti-diarrheal medication makes the problem worse because it slows the elimination of the toxin from the body. Drink fluids to stay hydrated. Seek medical attention if you become faint, weak, or dizzy, or if you notice that you are urinating very little or have blood in your urine, have a rash, or have blood in the stool. (Facts and Comparisons 2001)

Discussion

Escherichia coli (E. coli) are members of a large group of bacterial germs that inhabit the intestinal tract of humans and other warm blooded animals (mammals, birds). Newborns have a sterile alimentary tract which within two days becomes colonized with E. coli.

More than 700 serotypes of E. coli have been identified. The different E. coli serotypes are distinguished by their “O” and “H” antigens on their bodies and flagella, respectively. The E. coli serotypes that are responsible for the numerous reports of contaminated foods and beverages are those that produce Shiga toxin (Stx), (USP DI 2004) so called because the toxin is virtually identical to that produced by another bacteria known as Shigella dysenteria type 1 (that also causes bloody diarrhea and hemolytic uremic syndrome [HUS] in emerging countries like Bangladesh). The best known and most notorious Stx-producing E. coli is E. coli O157:H7. It is important to remember that most kinds of E. coli bacteria do not cause disease in humans, indeed, some are beneficial, and some cause infections other than gastrointestinal infections, such urinary tract infections. This section deals specifically with Stx-producing E. coli, including specifically E. coli O157:H7.

Shiga toxin is one of the most potent toxins known to man, so much so that the Centers for Disease Control and Prevention (CDC) lists it as a potential bioterrorist agent (CDC, n.d.). It seems likely that DNA from Shiga toxin-producing Shigella bacteria was transferred by a bacteriophage (a virus that infects bacteria) to otherwise harmless E. coli bacteria, thereby providing them with the genetic material to produce Shiga toxin. (Facts and Comparisons 2001)

Although E. coli O157:H7 is responsible for the majority of human illnesses attributed to E. coli, there are additional Stx-producing E. coli (e.g., E. coli O121:H19) that can also cause hemorrhagic colitis and post-diarrheal hemolytic uremic syndrome (D+HUS). HUS is a syndrome that is defined by the trilogy of hemolytic anemia (destruction of red blood cells), thrombocytopenia (low platelet count), ...