Verotoxigenic E. coli and its importance in food hygiene

Verotoxigenic Escherichia coli (VTEC) or Shigatoxin producing Escherichia coli (STEC) is an important pathogenic E. coli that can cause diarrhea or hemorrhagic colitis in humans. Hemorrhagic colitis occasionally progresses to hemolytic uremic syndrome (HUS), an important cause of acute renal failure in children and morbidity and mortality in adults. In the elderly, the case fatality rate for HUS can be as high as 50%. Escherichia. coli O157:H7 has been recognized as a cause of this syndrome since the 1980s. The reservoirs for STEC O157:H7 are ruminants, particularly cattle and sheep, which are infected asymptomatically and shed the organism in feces. Other animals such as rabbits, pigs and poultry can also carry this organism. Infections with STEC in other serogroups, including members of O26, O91, O103, O104, O111, O113, O117, O118, O121, O128 and O145, are increasingly recognized as causes of hemorrhagic colitis and HUS. Humans acquire STEC by direct contact with animal carriers, their feces, and contaminated soil or water, or via the ingestion of underdone ground beef, other animal products, and contaminated vegetables and fruits. Thorough cooking of raw meats, pasteurization of milk, treatment of private water supplies, and the avoidance of cross-contamination from raw meats or cattle feces to other foods are the most effective ways of preventing STEC infections. Generally, the detection of STEC is laborious, and currently there are no simple, inexpensive methods available for routine isolation of all STEC strains.