Environmental Engineering Reference
In-Depth Information
47
◦
C) for optimum growth in the absence of air. This enterotoxin is destroyed
above 140
◦
F(60
◦
C). Bacteria in spore form are more difficult to destroy than
when in vegetative form. The vegetative cell is killed at a temperature of 150
◦
F
(66
◦
C); spores survive 212
◦
F (100
◦
C) for 1 hour or more. Spores are dormant,
that is, inactive or not growing; they must germinate and become vegetative
cells to grow. The term germination refers to the process involved when a spore
changes into a vegetative cell.
Other bacterial toxins may also contaminate food, leading to food poisoning.
Certain specific strains of staphylococcis (
S. aureus
) commonly found in skin
infections, hands, feces, and discharges from the nose and throat are frequently
associated with food poisoning. Staphylococci multiply under favorable temper-
ature conditions, producing highly temperature and chemical resistant enterotox-
ins.. Common food vehicles associated with staphylococcal enterotoxins include
contaminated ham, potato and chicken salads, sauces, poultry, and custard or
cream-filled bakery products. Even after refrigeration and reheating, the con-
sumption of food containing sufficient toxin, may cause food poisoning.
Botulism is caused by ingestion of a toxin produced by
Clostridium
botulinum
.The
C. botulinum
in improperly canned or bottled low-acid food and
in improperly cooled food will also produce a toxin (neurotoxin), but this poison
is destroyed by boiling and cooking.
Clostridium botulinum
is rarely found in
commercially canned foods but can be a risk in home-canned foods. During
1950 to -2005, CDC reported 405 events of foodborne botulism, of which 92
percent were linked to home-processed foods and 8 percent to commercially
processed foods, including those prepared in restaurants.
72
Outbreaks associated
with deficiencies in the commercial canning process are rare; in 2007, the
outbreak associated with commercially canned chili sauce was the first such
outbreak reported in the United States since 1974.
72
Botulism is also a hazard
in prepared foods in which oxygen has been driven off in cooking and in which
the food is shielded from oxygen and kept warm, permitting surviving spores
to germinate and produce toxin, such as in potato salad, beef stew, meat pie,
sauteed onions, and garlic in olive oil.
Clostridium botulinum
is reported not to
grow at an
a
w
less than 0.93.
Intestinal or infant botulism can result from intraintestinal production and
absorption of botulinum toxin, which is thought to result from the colonization
of spores found in foods and dust and entering the gastrointestinal tract of the
infant (2 to 38 weeks of age). Intestinal botulism is the most common form of
human botulism in the United States (check reference list for this CDC. Botulism
in the United States, 1899 - 1996: handbook for epidemiologists, clinicians, and
laboratory workers. Atlanta, Georgia: U.S. Department of Health and Human
Services, CDC, 1998), is a result of swallowing
C
. botulism spores. One source of
these spores is honey. Honey should not be fed to infants less than 1 year of age.
The spread of diseases such as trichinosis, taeniasis, and salmonellosis associ-
ated with the consumption of foods of animal origin can be prevented by thorough
cooking. Using only inspected meats, prohibiting the feeding of uncooked garbage
or offal to hogs, and good sanitation will also help.
