Fundamental Food Microbiology, Third Edition - Fuad Fathir

FOODBORNE INTOXICATIONS 347
(14.9%), and picnics (8.5%). A high percentage of outbreaks occurred between May
and October (63.8%), with the highest frequency in August (21.3%). In the case of
imported foods, a raw or processed food exported from a country can have Sta.
aureus toxins, but can cause food poisoning in a different country. This is exemplified
by at least six outbreaks of staphylococcal gastroenteritis in 1989 in the U.S. from
the consumption of dishes prepared by using enterotoxin-containing canned mushrooms
processed in a plant in the People's Republic of China. Sta. aureus probably
grew before canning and the enterotoxin, being heat-stable, remained potent after
canning.
F. Prevention (Reduction) of the Disease
The normal occurrence of Sta. aureus in raw food materials, among food handlers,
and many food environments makes it impossible to produce nonsterile foods that
are free of this bacterium. Thus, a zero tolerance is not economically possible to
achieve. Many foods can contain Sta. aureus, and consumption of a food containing
100 or 500 cells/g (or /ml) will, in all probability, not make a person sick (unless
the food has large amounts of preformed toxin). To reduce the incidence of staphylococcal
food poisoning, the aim is to reduce initial load of Sta. aureus in a food
by proper selection of the quality of the raw materials and ingredients, sanitation of
the food environments, and proper personal hygiene among food handlers. 3–5 People
with respiratory diseases, acute types of facial acne, skin rash, and cuts in hands
should not handle the food. Where possible, products should be heat-treated to ensure
killing of live cells. Following heating, recontamination of the products should be
avoided. The most important aim is to chill the processed products and ready-to-eat
foods to £5�C quickly. Suitable preservatives can also be used to kill or arrest growth.
The inside of the food, and not only the surface, should reach the chilled temperature,
preferably within 1 h. Finally, the food should not be subjected to temperature abuse
and stored for a long period of time at growth temperature before eating. Once heatstable
toxins are formed, heating before eating does not ensure safety.
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Table 24.1 Food Types Involved in Confirmed Staphylococcal Food Poisoning
Outbreaks from 1973 to 1987 in the U.S.
Food Type % Outbreaksa Food Type % Outbreaks
Pork 16.2 Fish 1.3
Bakery products 7.1 Dairy products 1.7
Beef 6.0 Fruits and
vegetables
1.1
Turkey 5.5 Ethnic foods 1.1
Chicken 3.8 Other 37.2b Eggs 2.5 Unknown 6.5
a Out of a total of 367 outbreaks.
b The foods included in the "other" category are not known. However, salads were implicated
in many outbreaks. Between 1983 and 1987, salads were involved in ca. 13% of the total
staphylococcal foodborne disease outbreaks.