the presence of hundreds of thousands or more of these organisms per gram of food substantiates the diagnosis.
Illness typically occurs 8-15 h after ingestion of the contaminated food. The symptoms, which
include intense abdominal cramps, gas, and diarrhea (nausea and vomiting are rare), have been
attributed to a protein enterotoxin produced during sporulation of the organism in the intestine.
The enterotoxin can be detected in sporulating cultures, and a method for this purpose is
included. A high correlation has been established between the ability of C. perfringens strains to
produce enterotoxin and their ability to cause food poisoning. However, it is difficult to obtain
consistent sporulation with some strains.
C. perfringens cells lose their viability when foods are frozen or held under prolonged
refrigeration unless special precautions are taken. Such losses may make it difficult to establish
C. perfringens as the specific cause of a food poisoning outbreak. It is recommended that
samples which cannot be examined immediately be treated with buffered glycerin-salt solution
and stored or shipped frozen to the laboratory as described below.