Fundamental Food Microbiology, Third Edition - Fuad Fathir

FOODBORNE INFECTIONS 373
4. Prevention
The pathogen is sensitive to pasteurization temperature. Thus, proper heat treatment,
elimination of postheat contamination for a ready-to-eat food, and refrigeration of
a food soon after preparation are necessary to control the disease. In addition, proper
sanitation at all stages of food processing and handling is an important factor.
Individuals suspected of being carriers should not handle food, especially ready-toeat
food. 16,17
C. Gastroenteritis due to EHEC
1. Characteristics
The principal serotype associated with enterohemorrhagic colitis is Esc. coli
O157:H7. As opposed to other Esc. coli, it does not ferment sorbitol or have glucuronidase
activity. Like other Esc. coli, it grows rapidly at 30 to 42�C, grows poorly
at 44 to 45�C, and does not grow at 10�C or below. Strains resistant to pH 4.5 or
below have been identified. The organism is destroyed by pasteurization temperature
and time and killed at 64.3�C in 9.6 sec. The cells survive well in food at –20�C. 17–21
2. Toxins
Esc. coli O157:H7 produces a verotoxin (VTI), or Shiga toxin (ST). For this, it is
also designated as VTEC or STEC. More than one toxin can be involved in the
disease and the symptoms related to it. It is not known whether the pathogen also
produces invasive factors. The cells probably colonize in the intestine by adhering
to the epithelial cells and produce toxins, which then act on the colon. Toxins are
also absorbed into the bloodstream and damage the small blood vessels in the
intestine, kidneys, and brain. 19
3. Disease and Symptoms
Esc. coli O157:H7 causes hemorrhagic colitis, hemolytic uraemic syndrome (HUS),
and thrombotic thrombocytopenic purpura (TTP). Symptoms occur 3 to 9 d after
ingestion and generally last for 4 d. The colitis symptoms include a sudden onset
of abdominal cramps, watery diarrhea (which in 35 to 75% of cases turns to bloody
diarrhea), and vomiting. Fever may or may not be an associated symptom. Damage
to the lining of the large intestine causes bleeding. Toxins also cause breakdown of
red blood cells, and clotting in small blood vessels of the kidney, causing kidney
damage and occasional kidney failure, causing HUS. It can be fatal, particularly in
children. TTP results from a blood clot in the brain, with seizures, coma, and often
death. 17–21
4. Food Association
The pathogen is probably present in the intestine of animals, particularly in dairy
cattle, without producing symptoms. Food of animal origin, especially ground beef,
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