BACTERIA THAT CAUSE
FOODBORNE ILLNESS
Campylobacter
jejuni, Clostridium botulinum, Clostridium perfringens, Cyclospora
Cayetanensis, Escherichia coli 0157:H7, Listeria monocytogenes, Salmonella,
Shigella, and Staphylococcus aureus are examples of bacteria that can cause
foodborne illness. Refer to Table 10-1.
Campylobacter jejuni is
believed to be one of the most prevalent causes ofdiarrhea. It is commonly
found in the intestinal tracts of cattle, pigs, sheep, chickens, turkeys, dogs,
and cats and can contaminate meat during slaughter. It is caused by the
ingestion of live bacteria.
It can take from 2 to
5 (or more) days to develop after infection and may last up to 10 days.
Symptoms include diarrhea (sometimes bloody), fever, headache, muscle and
abdominal pain, and nausea. It can be transmitted to humans via unpasteurized
milk; contaminated water; and raw or undercooked meats, poultry, and shellfish.
Clostridium botulinum is found in soil and water, on plants, and in the intestinaltracts of animals and fish. The spores of these bacteria can divide and produce toxin in the absence of oxygen. (Spores are single cells that are produced asexually, each of which is able to develop into a new organism. They have thick, protective walls that allow them to survive unfavorable conditions.) This means that the toxin can be produced in sealed containers such as cans, jars, and vacuum-packaged foods.
The spores are
extremely heat resistant and must be boiled for 6 hours before they will be
destroyed. Such a lengthy time will, of course, destroy the food they have
infected. The toxin, however, can be destroyed by boiling for 20 minutes. This
toxin causes botulism, which is perhaps the
rarest but most deadly of all food poisonings. Symptoms usually appear within 4
to 36 hours after eating and include double vision, speech difficulties,
inability to swallow, and respiratory paralysis. If botulism is not properly
treated, death will result in 3 to 10 days. The fatality rate in the United
States is about 65%.
Great care must be
taken to prevent botulism when canning foods at home. The Centers for Disease
Control and Prevention (CDC) reported that from 1950 through 1996, 289 botulism
outbreaks have been traced to home-processed foods and 31 to commercially
processed foods, including foods served in restaurants. The type of food
processing was unknown for the remaining 124 outbreaks. Vegetables were the
most important carrier for themeans that the toxin can be produced in sealed
containers such as cans, jars, and vacuum-packaged foods.
The spores are
extremely heat resistant and must be boiled for 6 hours before they will be
destroyed. Such a lengthy time will, of course, destroy the food they have infected.
The toxin, however, can be destroyed by boiling for 20 minutes. This toxin
causes botulism, which is perhaps the
rarest but most deadly of all food poisonings. Symptoms usually appear within 4
to 36 hours after eating and include double vision, speech difficulties,
inability to swallow, and respiratory paralysis. If botulism is not properly
treated, death will result in 3 to 10 days. The fatality rate in the United
States is about 65%.
Great
care must be taken to prevent botulism when canning foods at home. The Centers
for Disease Control and Prevention (CDC) reported that from 1950 through 1996,
289 botulism outbreaks have been traced to home-processed foods and 31 to
commercially processed foods, including foods served in restaurants. The type
of food processing was unknown for the remaining 124 outbreaks. Vegetables were
the most important carrier for thebotulism toxin in the United States during
this time period. Raw honey has also been identified as a source. If a can
bulges, Clostridium botulinum may be
present and can be fatal. A good rule of thumb is: “If in doubt, throw it out”
where children and animals cannot reach it.
Clostridium perfringens
is often called the “cafeteria” or
“buffet germ” becauseit tends to infect those who eat food that has been
standing on buffets or steam tables for long periods. Clostridium perfringens is found in soil dust, sewage, and the
intestinal tracts of animals. It is a spore-forming pathogen that needs little
oxygen. The bacteria are destroyed by cooking, but the spores can survive it.
Clostridium perfringens
is transmitted by eating heavily
contaminatedfood. Symptoms include nausea, diarrhea, and inflammation of the
stomach and intestine. Symptoms may appear within 6 to 24 hours of ingestion
and last approximately 24 hours.
To
best prevent it, hot foods should be kept at or above 140°F and cold foods
below 40°F. Leftovers should be heated to 165°F before serving. Foods should be
stored at temperatures of 40°F or lower. People with compromised immune systems
should be very cautious concerning Clostridium
perfringens.
Cyclospora cayetanensis
is a parasite that causes
gastroenteritis. Until 1996most cases were experienced by overseas travelers,
but several domestic out-breaks have been reported in recent years. This
bacteria is commonly found in the feces of an infected person and can be
transmitted by poor hygiene. It has been found in unclean water.
Symptoms
are watery diarrhea, abdominal cramps, decreased appetite, and a low-grade
fever. These symptoms could last off and on for several weeks. Those with
compromised immune systems, children, and the elderly are at greatest risk of
complications.
Cyclospora has
an incubation period of 1 week, is associated with inva-sion of the small
intestine, and is manifested by the preceding symptoms. The parasite’s natural
ecology, infective dose, and host range are unknown. It is known that Cyclospora does not multiply outside the
host.
It
is strongly recommended that clean water be used for drinking and the
irrigation of produce. Thorough washing of fruits and vegetables and the
practice of good hygiene by food handlers help to prevent the spread of this
bacteria.
Escherichia coli, commonly called E. coli, is a group of bacteria that
can cause ill-ness in humans. E. coli 0157:H7 is a very infectious strain of
this group. These bacteria can be found in the intestines of some mammals
(including humans and animals used for food), in raw milk, and in water
contaminated by animal or human feces.
E. coli are transmitted to
humans through contaminated water,unpasteurized milk or apple juice, raw or
rare ground beef products, unwashed fruits or vegetables, and directly from
person to person. Plant foods can be con-taminated by fertilization with raw
manure or irrigation with contaminated water.
Symptoms include
severe abdominal cramps, diarrhea that may be watery or bloody, and nausea.
Sometimes, however, E. coli 0157:H7 can cause hemorrhagic colitis (inflammation
of the colon). This in turn can result in hemolytic
uremic syndrome (HUS) in children, which can damage the kidneys.
E. coli can be controlled by
careful choice and cooking of foods. All meatsand poultry should be cooked
thoroughly. Ground beef, veal, and lamb should be cooked to 160°F and ground
poultry to at least 165°F. Fruits and vegetables should be carefully washed,
and unpasteurized milk and other dairy products and vegetable and fruit juices
should be avoided. People with compromised im-mune systems should be especially
vigilant.
Listeria monocytogenes is a bacteria often
found in human and animal intestinesand in milk, leafy vegetables, and soil. It
can grow in the refrigerator and can be transmitted to humans by unpasteurized
dairy foods such as milk, soft cheeses, and ice creams and via raw leafy
vegetables and processed meats.
Listeria monocytogenes can affect a person
from 12 hours to 8 daysafter ingestion. Symptoms include fatigue, fever,
chills, headache, backache, abdominal pain, and diarrhea. It can develop into
more serious conditions and cause respiratory distress, spontaneous abortion,
or meningitis.
To prevent infection
by Listeria monocytogenes, meats and
poultry should be thoroughly cooked and salad greens carefully washed.
Attention must be paid to all dairy products—especially the unfamiliar from new
sources—to be certain they have been pasteurized.
Salmonellosis
(commonly called salmonella) is an
infection caused by the Salmonella bacteria.Salmonellacan be found in raw
meats, poultry, fish,milk, and eggs. It is transmitted by eating contaminated
food or by contact with a carrier. Salmonellosis is characterized by headache,
vomiting, diarrhea, abdominal cramps, and fever. Symptoms generally begin from
6 to 48 hours after eating. In severe cases, it can result in death. One
species of Salmonella causes typhoid
fever. Those who suffer the most severe cases are typically the very young, the
elderly, and the weak or incapacitated.
Refrigeration (40°F or
lower) inhibits the growth of these bacteria, but they can remain alive in the
freezer and in dried foods. Salmonella
bacteria are destroyed by heating to at least 140°F for a minimum of 10
minutes.
To prevent
contamination, thaw poultry and meats in the refrigerator or microwave and cook
immediately. Avoid cross-contamination of raw and cooked foods by carefully
cleaning utensils and counter surfaces that were in contact with raw food. Raw
or undercooked eggs, or foods that contain them,should not be eaten. Even a
taste of raw cookie dough or Caesar salad dressing made with raw egg yolk can
cause contamination. People with compromised immune systems should be
especially careful.
Shigella bacteria are found in
the intestinal tract and thus the feces of infected in-dividuals. The disease
they cause is called shigellosis.
These bacteria are typically passed on by an infected food handler who did not
wash his or her hands properly after using the toilet. They are also found on
plants that were fertilized with un-treated animal feces or given contaminated
water. Shigella are destroyed by
heat, but infected cold foods such as tuna, chicken, or egg salads are common
carriers.
Shigellosis can occur
from 1 day to a week following infection. Symptoms include diarrhea (sometimes
with blood and mucus), fever, chills, headache, nausea, and abdominal cramps
and can lead to dehydration. Some people, however, experience no symptoms.
Staphylococcus aureus bacteria are found on
human skin, in infected cuts andpimples, and in noses and throats.
Staphylococcal poisoning is commonly called staphylococcus
(staph). These bacteria grow in meats; poultry; fish; egg dishes;salads
such as potato, egg, macaroni, and tuna; and cream-filled pastries. This
poi-soning is transmitted by carriers and by eating foods that contain the
toxin these bacteria create.
Symptoms, which
include vomiting, diarrhea, and abdominal cramps, begin within ½ to 8 hours
after ingestion of the toxin and last from 24 to 48 hours. Staph is considered
a mild illness.
The growth of these
bacteria is inhibited if foods are kept at temperatures above 140°F or below
40°F. Their toxin can be destroyed by boiling the food for several hours or by
heating it in a pressure cooker at 240°F for 30 minutes. Both of these methods
would destroy both the appeal and nutrient content of the infected foods. It is
more practical to safely discard foods suspected of being contaminated.
Related Topics
Privacy Policy, Terms and Conditions, DMCA Policy and Compliant
Copyright © 2018-2023 BrainKart.com; All Rights Reserved. Developed by Therithal info, Chennai.