Principles of Food Sanitation

cream, meat, fresh vegetables, finfish, oys-
ters, and other seafood. It is a facultative
anaerobic, gram-negative rod that is motile
with polar flagellum. The temperature range
for growth is 4ºC to 43ºC with an optimum
of 28ºC. The pH range is 4.5 to 9.0 and
the maximum concentration of salt for
growth is 4.0%.A. hydrophilacan cause gas-
troenteritis in humans and infections in
patients immunocompromised by treatment
for cancer.

Bacillus cereusFoodborne Illness

B. cereusis a gram-positive, rod-shaped,
spore-forming obligate aerobe that is widely
distributed. Although some strains of this
microbe are psychrotrophic and able to grow
at 4 to 6ºC, most proliferate at 15 to 55ºC
with an optimal temperature of 30ºC. The
normal habitat for B. cereusis dust, water,
and soil. It is found in many foods and food
ingredients. Because this microorganism is a
spore-former, it is heat resistant. Most of the
spores have moderate resistance, but some
have high heat resistance. The pH range for
the proliferation of this bacterium is 5.0 to
8.8 with a minimum Awof 0.93.
This microorganism produces two types of
gastroenteritis: emetic and diarrheal. The
diarrhetic typeis characterized by relatively
mild symptoms, such as diarrhea and
abdominal pain that occur 8 to 16 hours
after infection and may last for approxi-
mately 6 to 24 hours. In the emetic form of
B. cereusillness, the symptom is primarily
vomiting (which occurs within 1 to 6 hours
after infection and endures for 24 or less
hours), although diarrhea may occur also.
TheB. cereusemetic toxin is performed in
the food and, like Streptococcus faecalis, it is
heat stable. The emetic form, which is more
severe than the diarrhetic type, is caused by
the production of an enterotoxin within the
gut. Outbreaks have occurred as a result of
consuming rice or fried rice served in restau-

rants or from warmed-over mashed pota-

toes. Other foods associated with this food-

borne illness include cereal dishes, vegetables,

minced meat, meat loaf, milk products,

soups, and puddings. The number of cells

required for an outbreak is 5 to 8 log colony-

forming units (CFU) per gram of food. This

illness is best controlled by proper sanitation

in restaurants and by holding starchy cooked

foods above 50ºC or refrigerating at below

4ºC within 2 hours after cooking to prevent

growth and toxin production.

Botulism

Botulism is a foodborne illness that results

from the ingestion of a toxin produced by

C. botulinumduring its growth in food. This

microbe is an anaerobic, gram-positive, rod-

shaped, spore-forming, gas-forming bac-

terium that is found primarily in the soil. The

optimal growth temperature is 30 to 40ºC.

Temperature growth ranges are normally 10

to 50ºC except for type E, which thrives at

3.3 to 45Cº. There are currently eight differ-

ent botulinum toxins recognized and sero-

logically classified (see Table 3–1). The

extremely potent toxin (the second most

powerful biological poison known to

humans) produced by this microorganism

affects the peripheral nervous system of the

victim. Infants can be affected by this disease

through the ingestion of as few as 10 to 100

spores that germinate in the intestinal tract

and produce toxin. Death occurs in approxi-

mately 60% of the cases from respiratory

failure. The characteristics, including symp-

toms, incubation time, involved food, and

preventive measures, of botulism and other

common food poisonings are presented in

Table 3–3.

BecauseC. botulinummay occur in the

soil, it is also present in water. Therefore,

seafoods are a more viable source of botu-

lism than are other muscle foods. However,

the largest potential sources of botulism are

The Relationship of Microorganisms to Sanitation 37