5. Five virulence groups of E. coli are recognized:
1. enteroaggregative(EAggEC),
2. enterohemorrhagic (EHEC),
3. enteroinvasive (EIEC),
4. enteropathogenic(EPEC), and
5. enterotoxigenic (ETEC).
6. • •Have fimbriae which
aggregate tissue culture cells.
• EAEC bind to the intestinal mucosa
to cause watery diarrhea without
fever.
• They are noninvasive.
•An enteroaggregative E. coli (EAEC)
strain of serotype O92:H33 was found
to be the causative agent . The strain
showed an aggregative pattern of
adherence to HEp-2 cells, did not
produce a biofilm .
Enteroaggregative(EAggEC)
8. Enteroinvasive (EIEC)
EIEC infection causes a syndrome that is
identical to shigellosis, with profuse diarrhea
and high fever.
highly invasive, and they utilize adhesion
proteins to bind to and enter intestinal cells.
They produce no toxins, but severely damage
the intestinal wall through mechanical cell
destruction.
After the E. coil strain pass through the epithelial
by penetration, the endocytosis vacuole gets lysed,
the strain multiplies using the host cell machinery,
extend to the adjacent epithelial cell.
The invasion of the cells can trigger a mild
form of diarrhea or dysentery, often mistaken
for dysentery caused by Shigella species
10. ETEC uses fimbrial adhesins(projections from the
bacterial cell surface) to bind enterocyte cells in
the small intestine ETEC can produce two
proteinaceous enterotoxin: The larger of the two
proteins, LT enterotoxin, is similar to cholera
toxin in structure and function.
The smaller protein, ST enterotoxin causes
cGMP accumulation in the target cells and a
subsequent secretion of fluid and electrolytes into
the intestinal lumen.
ETEC strains are noninvasive, and they do not
leave the intestinal lumen. ETEC is the leading
bacterial cause of diarrhea in children in the
developing world, as well as the most common
cause of travelers diarrhea . Each year, ETEC
causes more than 200 million cases of diarrhea
and 380,000 deaths, mostly in children in
developing countries
Enterotoxigenic (ETEC).
11. .
Shiga toxin-producing Escherichia coli (STEC)
THE strains have emerged as an important cause of serious human
gastrointestinal disease, which may result in life-threatening complications
such as hemolytic-uremic syndrome.
Acquired as a food borne or from a contaminated
water supply and caused
by E.coli O157:H7
Schistocyte
12. Prevention
• Hand washing
• Proper food handling and complete
cooking
• Pasteurization of milk and juices
• Adequate sanitation
• Safe water supplies
Treatment
• Rapid replacement of fluids and
electrolytes
• Anti-nausea medication
• Antimicrobials may be used in severe
cases.
For illness caused by E. coli O157:H7, no current
treatments can cure the infection, relieve
symptoms or prevent complications. For most
people, the best option is to rest and drink plenty
of fluids to help with dehydration and fatigue.
Avoid taking an anti-diarrheal medication — this
slows your digestive system down, preventing your
