Fundamental Food Microbiology, Third Edition - Fuad Fathir

FOODBORNE TOXICOINFECTIONS 393
1970s, it was involved in more than 7% of the total foodborne outbreaks and more
than 10% of the total number of cases. In the 1980s, the incidence dropped to ca.
3% of the total outbreaks, affecting ca. 5% of the total cases. The outbreaks generally
occur with some foods that were prepared in advance by heating and then kept warm
for several hours before serving. In the majority of the instances, these situations
are associated with feeding many people within a short period of time in cafeterias,
restaurants, schools, and banquets (banquet disease). Between 1983 and 1987, out
of 24 outbreaks, 12 were associated with such institutions and only 1 outbreak
occurred with food prepared at home. As the disease produces mild symptoms, many
incidents are probably not reported. Thus, the reported cases could be only a fraction
of the actual numbers. 1,2
B. Characteristics
The cells are Gram-positive rods, motile, and sporeformers. Cells vary in size and
can form small chains. Clo. perfringens is anaerobic but can tolerate some air
(oxygen). The vegetative cells are sensitive to low-heat treatment (pasteurization),
but the spores are extremely heat resistant, and some can survive even boiling for
several hours. The cells are resistant to D-cycloserine. In the presence of suitable
substrates, H 2S is formed during growth. The cells need several amino acids for
growth. Thus, they can grow very effectively in many protein foods. The temperatures
of growth of vegetative cells and germination of spores and outgrowth range
between 10 and 52�C. The optimum growth occurs at ca. 45�C. At optimum
conditions, cell multiplication can be very rapid, in ca. 9 min. The cells fail to
grow well at pH 5%, at A w,