Foodborne Toxico-Infections ◾ 383
detected in a growing culture within 24 hours at 35°C. However, the toxin can be produced by
the cells growing at 25°C–40°C.
Disease and Symptoms
ETEC strains are regarded as the cause of traveler’s diarrhea, a nonfatal diarrheal disease. Ingestion
of a high level (10 6–9 cells) of viable cells of the organisms by adults is necessary for the symptoms
to occur within 24–72 hours. Symptoms include mild to severe diarrhea that lasts for 24–30
hours. In severe cases, dehydration, prostration, and shock may accompany the diarrhea. Not all
individuals show symptoms; those who develop symptoms may shed the organisms in feces after
recovery.
Food Association
Many types of foods, including meat products, fish, milk and dairy products, vegetables, baked
products, and water have been associated with gastroenteritis of Esc. coli origin in many countries.
Direct or indirect contaminations of these foods (and water) with fecal materials, along with
improper storage temperature and inadequate heat treatment, were involved in these incidences.
Prevention
The most important factor in the prevention of gastroenteritis in humans by pathogenic Esc. coli is to
prevent contamination of food and water, directly or indirectly, by fecal matters. This can be achieved
by developing effective sanitation in water supplies and treating and disposing sewage. The other factor is to prevent contamination of food from poor personal hygiene by people who shed the pathogen.
Finally, one needs to recognize that even if the pathogen is present in very small initial numbers in a
food, temperature abuse of the food can facilitate multiplication of cells to the high levels necessary for
the disease symptoms. Thus, food should be refrigerated or eaten quickly, preferably after reheating.
Detection Methods
The detection methods used involve selective enrichment of the sample (food, water, and feces),
isolation of pathogens on selective agar medium, and biochemical characterization of suspected
isolates (Chapter 42). Confirmation tests to detect toxins involve one or more serological tests
(ELISA). Other methods to detect toxins include injecting test material into the ligated ileal loop
of infant mice or exposing Y-1 adrenal cells to toxin (for LT) or both.
Conclusion
Foodborne pathogens in this group include several gram-positive spore-formers and gramnegative rods. The cells of spore-formers, when consumed through contaminated foods, sporulate
in the gastrointestinal (GI) tract and release the toxin. In contrast, following consumption, gramnegative rods multiply rapidly in the GI tract and die off, releasing toxins. The symptoms, mainly
enteric, are associated with the toxins. They are usually required in very high numbers to cause the
diseases. Proper sanitation and refrigeration can be used to reduce the incidence.
detected in a growing culture within 24 hours at 35°C. However, the toxin can be produced by
the cells growing at 25°C–40°C.
Disease and Symptoms
ETEC strains are regarded as the cause of traveler’s diarrhea, a nonfatal diarrheal disease. Ingestion
of a high level (10 6–9 cells) of viable cells of the organisms by adults is necessary for the symptoms
to occur within 24–72 hours. Symptoms include mild to severe diarrhea that lasts for 24–30
hours. In severe cases, dehydration, prostration, and shock may accompany the diarrhea. Not all
individuals show symptoms; those who develop symptoms may shed the organisms in feces after
recovery.
Food Association
Many types of foods, including meat products, fish, milk and dairy products, vegetables, baked
products, and water have been associated with gastroenteritis of Esc. coli origin in many countries.
Direct or indirect contaminations of these foods (and water) with fecal materials, along with
improper storage temperature and inadequate heat treatment, were involved in these incidences.
Prevention
The most important factor in the prevention of gastroenteritis in humans by pathogenic Esc. coli is to
prevent contamination of food and water, directly or indirectly, by fecal matters. This can be achieved
by developing effective sanitation in water supplies and treating and disposing sewage. The other factor is to prevent contamination of food from poor personal hygiene by people who shed the pathogen.
Finally, one needs to recognize that even if the pathogen is present in very small initial numbers in a
food, temperature abuse of the food can facilitate multiplication of cells to the high levels necessary for
the disease symptoms. Thus, food should be refrigerated or eaten quickly, preferably after reheating.
Detection Methods
The detection methods used involve selective enrichment of the sample (food, water, and feces),
isolation of pathogens on selective agar medium, and biochemical characterization of suspected
isolates (Chapter 42). Confirmation tests to detect toxins involve one or more serological tests
(ELISA). Other methods to detect toxins include injecting test material into the ligated ileal loop
of infant mice or exposing Y-1 adrenal cells to toxin (for LT) or both.
Conclusion
Foodborne pathogens in this group include several gram-positive spore-formers and gramnegative rods. The cells of spore-formers, when consumed through contaminated foods, sporulate
in the gastrointestinal (GI) tract and release the toxin. In contrast, following consumption, gramnegative rods multiply rapidly in the GI tract and die off, releasing toxins. The symptoms, mainly
enteric, are associated with the toxins. They are usually required in very high numbers to cause the
diseases. Proper sanitation and refrigeration can be used to reduce the incidence.