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This bacterium is typically found on rice and can produce two different toxins, one causing
diarrhea and the other causing vomiting—which is the more common form. After cooking,
heat-resistant spores germinate on the cooling rice, and a toxin is produced which is not
destroyed by reheating (e.g. fried rice).
Bacillus cereus (gastroenteritis)
This bacterium is one of the most common causes of bacterial diarrhea worldwide. Poultry
is a common source, and the relatively low number of organisms needed to cause disease
means that only a small drop of chicken juice can cause illness. The bacterium invades the
small intestines and colon, damaging the mucosal surfaces. Signs and symptoms include
bloody or watery diarrhea, abdominal pain, cramps and fever.
Campylobacter jejuni (campylobacteriosis-gastroenteritis)
This anaerobic bacterium produces an extremely powerful and often fatal neurotoxin. It is
found in the environment and their spores can germinate in improperly canned food.
Patients can be helped if treated early with an antitoxin. Botulism is relatively rare in
developed countries. Signs and symptoms include flaccid paralysis, blurred vision,
difficulty swallowing, weakness and fatigue.
clostridium botulinum (botulism)
This spore-forming bacterium is found in the environment and typically contaminates meat
dishes. When food is improperly stored after cooking, this organism continues to multiply.
It produces an enterotoxin which causes diarrhea and abdominal cramps only. This is a
very common type of food poisoning.
clostridium perferengens (gastroenteritis)
This bacterium is part of the normal bacterial flora of the mammalian intestine, but there
are pathogenic strains which cause diarrhea. It is spread by fecal contamination of food and
water. It is often described as Traveler’s diarrhea. Signs and symptoms include diarrhea,
nausea and vomiting. One particular serotype, O157:H7 has been linked to undercooked
ground beef. The toxin produced by this strain damages the lining of the colon, resulting in
hemorrhagic colitis. Signs and symptoms include severe abdominal cramps, and watery
Escherichia coli- (gastroenteritis, dysentery)
For most people, this bacterium causes little or no food poisoning symptoms. However, for
those with weakened immune systems, fetuses and the newborn, this organism can cause a
serious, even fatal, disease. It is found in animal products, particularly soft cheeses and raw
meats, and can grow at refrigerator temperatures. This bacterium preferentially infects the
CNS of immunocompromised individuals. Infection in pregnant women can cause high
rates of spontaneous abortions or stillbirths.
listeria monocytogenes (listeriosis)
This bacterium has over 1400 stains, referred to as serovars. Only some serovars cause
food poisoning. The bacteria are found in the intestine of wild and domestic animals, and
their feces can contaminate foods such as poultry, eggs, milk, and vegetables. Reptiles are
especially likely to carry these bacteria. Perhaps more than 1 million people per year
contract salmonella food poisoning in the U.S. Signs and symptoms include nausea,
cramping, abdominal pain, watery diarrhea, fever and possibly vomiting after 6-48 hours.
Salmonella enterica serovar typhimurium- (salmonellosis, gastroenteritis)
Salmonella typhi is the most virulent serovar. The disease is a result of endotoxin release,
resulting in prolonged fever, abdominal pain, and a rash (rose spots). After recovery,
individuals may remain carriers.
Salmonella enterica serovar typhi
Food contaminated with Shigella dysenteriae gives rise to dysentery through the production of
an enterotoxin. Signs and symptoms include abdominal pain, fever, water stool with mucous
and blood, and dehydration.
Shigella species (shigellosis-dysentery)
This is an example of an intoxication. The toxins produced by this bacteria cause rapid onset of
symptoms. Resident bacteria on food workers are the primary cause of contamination of food.
The toxin can withstand up to 30 minutes of boiling. Signs and symptoms include severe
nausea, vomiting after 1-6 hours; may include abdominal pain, headache and fever.
Staphylococcus aureus- gastroenteritis
In the small intestine, an enterotoxin made by the bacterium interferes with water and
electrolyte reabsorption. Severe dehydration and death can occur without treatment. Signs and
symptoms include vomiting, painless but severe watery diarrhea. (vibrio)
This bacterium can produce symptoms that mimic appendicitis. Invasion of the cells of the
small intestine causes gastroenteritis. Common in the environment, it can be found in soil,
water, animals and animal products (i.e. milk). These bacteria can multiply even when refrigerated.
This protozoan is transmitted by fecally-contaminated water. Importantly, the cysts are not
killed by normal chlorination of drinking water or swimming pool water. Signs and symptoms
include profuse, chronic diarrhea, and abdominal cramps.
cryptosporidium parvum (gastroenteritis)
This bacterium causes inflammation of the colon. Ingested cysts hatch out trophozoites that
produce ulcers on the surface of the intestinal lining. Signs and symptoms include abdominal
pain and weight loss and bloody diarrhea in severe cases.
Entamoeba hystolitica (Amebiasis)
This bacterium is found on marine fish and shellfish. Illness is caused when the seafood is eaten raw, is poorly refrigerated, or is inadequately cooked. It is commonly found in places with
warm coastal waters and where raw seafood is often eaten. Gastroenteritis is characterized by
little nausea or vomiting.
Vibrio parahaemolyticus and Vibrio vulnificus
This bacterium is transmitted via cyst-contaminated drinking water. The trophozoites infect and attach to the mucosa of the small intestine, triggering the disease.
Giardia intestinalis (protozoa-flagellate)
This bacterium has a long incubation period. Outbreaks have been connected to contaminated
food. Signs and symptoms include watery diarrhea, nausea, abdominal pain and vomiting.
Cyclospora cayetanensis (Protozoa)
These small round RNA viruses are a common cause of gastroenteritis worldwide. Water
contaminated by human sewage is the most likely route of transmission, but they can also be
found in certain foods, especially shellfish. The illness is of short duration and is more
commonly found in older children and adults. Signs and symptoms include fever, watery
diarrhea, vomiting, abdominal cramps and nausea. (Rna non-enveloped)
Coxsackie A and B viruses produce symptoms that usually resolve spontaneously. Many
echoviruses also produce symptoms without long-term complications. Signs and syptoms
include watery diarrhea, vomiting and fever.
- Enteroviruses (coxackie a and b viruses)
- both cause enteritis
These viruses are the most common cause of infant gastroenteritis. In undeveloped countries,
there is a high level of mortality and the virus is spread by food and water contaminated by
human feces. Among children in developed countries, the virus is spread hand to mouth from
contaminated surfaces. In the U.S., they account for 50% of all childhood hospitalizations for
dehydration. Dehydration is more likely in infants who can become listless and lethargic. Signs
and symptoms include fever, diarrhea, vomiting, abdominal cramps, nausea and headache.
Rotavirus (non-enveloped Rna viruses)