Fundamental Food Microbiology, Third Edition - Fuad Fathir

394 FUNDAMENTAL FOOD MICROBIOLOGY
E. Disease and Symptoms
The enterotoxin causes only gastroenteritis. The symptoms appear 8 to 24 h following
ingestion of a large number of viable cells (� 5 ¥ 10 5 /g) through a food. The main
symptoms are diarrhea and abdominal pain. Nausea, vomiting, and fever also can occur
but are less common. The toxin changes the permeability of intestinal cells. Fatality,
although rare, can occur among the very young, elderly, and sick. Symptoms generally
disappear within 24 h. It is considered a mild disease and is seldom reported. 3–5
F. Food Association
Raw meat from animals and birds is most commonly contaminated with the spores
and cells from the digestive tract content, whereas vegetables and spices commonly
get them from soil and dust. As the bacterium has some amino acid requirements
for growth, meat and meat-containing foods provide good environments for cell
growth. The foods commonly incriminated with the outbreaks include meat stews
(beef and poultry), roasts, meat pies, casseroles, gravies, sauces, bean dishes, and
some Mexican foods (tacos and enchiladas). Table 26.1 lists the food types involved
in 190 Clo. perfringens gastroenteritis outbreaks in the U.S. from 1973 to 1987.
Among the foods listed, protein-rich foods were involved in high percentages. 1 The
three most important contributing factors in these outbreaks, in order of importance,
were improper holding temperature, inadequate cooking, and contaminated equipment.
The most important predisposing cause was cooking food in large volumes
in advance, allowing it to cool slowly, then holding for a long period and often
serving without reheating. Cooking kills the vegetative cells, but the spores survive.
Large volumes of the food provide an anaerobic environment, and slow cooling not
only provides the temperature for the spores to germinate and outgrow but also
allows cells to multiply rapidly to reach high population levels before eating. The
food may not show any loss of acceptance quality. 3
G. Prevention
The presence of Clo. perfringens spores and cells in foods is not uncommon. Unless
viable cells are present in high numbers before eating, they cannot cause gastroenteritis;
thus, the aim is to keep the cell numbers low. This can be achieved by using
proper sanitation in all phases of food preparation and handling. Food should be
Table 26.1 Food Types Involved in Clo. perfringens Outbreaks from 1973 to 1987 in the
U.S.
No. of
Food Types Outbreaksa No. of
% Food Types Outbreaksa %
Beef 51 26.3 Finfish 3 1.6
Mexican foods 23 11.9 Shellfish 2 1.0
Turkey 19 9.8 Vegetables 1 0.5
Chicken 9 4.6 Other 46 23.8
Pork 8 4.1 Unknown 28 14.4
a Total cases were 12,234.