Chapter 27
Foodborne Gastroenteritis Caused
by Escherichia coli
Escherichia coli was established as a foodborne pathogen in 1971 when imported cheeses turned
up in 14 American states that were contaminated with an enteroinvasive strain that caused illness in
nearly 400 individuals. Prior to 1971, at least five foodborne outbreaks were reported in other countries,
with the earliest being from England in 1947. As a human pathogen, evidence suggests that it was
recognized as a cause of infant diarrhea as early as the 1700s.
60 Since the meatborne outbreaks in the
United States of 1982 and 1993, the status of this bacterium as a foodborne pathogen is unquestioned.
Escherichia coli as an indicator of fecal contamination is discussed in Chapter 20, culture and isolation
methods are covered in Chapter 10, and molecular and bioassay methods for its detection are covered
in Chapters 11 and 12. For a more detailed history of E. coli 0157:H7, see reference 69.
SEROLOGICAL CLASSIFICATION
Pathogenic strains of Escherichia are serologically typed in the same way as other Enterobacteriaceae, and the procedure is described in Chapter 11. For E. coli, over 200 O serotypes have been
recognized. Because the flagellar proteins are less heterogeneous than the carbohydrate side chains
that make up the O groups, considerably fewer H antigenic types exist (around 30).
THE RECOGNIZED VIRULENCE GROUPS
Based on disease syndromes and characteristics, and also on their effect on certain cell cultures and
serological groupings, five virulence groups of E. coli are recognized: enteroaggregative (EAggEC),
enterohemorrhagic (EHEC), enteroinvasive (EIEC), enteropathogenic (EPEC), and enterotoxigenic
(ETEC).
Enteroaggregative E. coli (EAggEC)
This group (also designated enteroadherent) is related to EPEC but the aggregative adherence
displayed by these strains is unique. Strains exhibit a “stacked-brick-type” of adherence to HEp-2
637
Foodborne Gastroenteritis Caused
by Escherichia coli
Escherichia coli was established as a foodborne pathogen in 1971 when imported cheeses turned
up in 14 American states that were contaminated with an enteroinvasive strain that caused illness in
nearly 400 individuals. Prior to 1971, at least five foodborne outbreaks were reported in other countries,
with the earliest being from England in 1947. As a human pathogen, evidence suggests that it was
recognized as a cause of infant diarrhea as early as the 1700s.
60 Since the meatborne outbreaks in the
United States of 1982 and 1993, the status of this bacterium as a foodborne pathogen is unquestioned.
Escherichia coli as an indicator of fecal contamination is discussed in Chapter 20, culture and isolation
methods are covered in Chapter 10, and molecular and bioassay methods for its detection are covered
in Chapters 11 and 12. For a more detailed history of E. coli 0157:H7, see reference 69.
SEROLOGICAL CLASSIFICATION
Pathogenic strains of Escherichia are serologically typed in the same way as other Enterobacteriaceae, and the procedure is described in Chapter 11. For E. coli, over 200 O serotypes have been
recognized. Because the flagellar proteins are less heterogeneous than the carbohydrate side chains
that make up the O groups, considerably fewer H antigenic types exist (around 30).
THE RECOGNIZED VIRULENCE GROUPS
Based on disease syndromes and characteristics, and also on their effect on certain cell cultures and
serological groupings, five virulence groups of E. coli are recognized: enteroaggregative (EAggEC),
enterohemorrhagic (EHEC), enteroinvasive (EIEC), enteropathogenic (EPEC), and enterotoxigenic
(ETEC).
Enteroaggregative E. coli (EAggEC)
This group (also designated enteroadherent) is related to EPEC but the aggregative adherence
displayed by these strains is unique. Strains exhibit a “stacked-brick-type” of adherence to HEp-2
637