C. perfringens has five serotypes
(A-E), based on the combinations of antigens.
Type A and C produce a toxin,
alfa-enterotoxin, that causes food poisoning.
C. perfringens is the most widely
disseminated of all pathogenic bacteria, typically being 10 to 100
times more numerous than E. coli in stool.
Type A serotype is the only one
commonly found in the colonic flora of animals and humans.
It is also omnipresent in the
environment, contaminating soil, water and air samples, clothing,
dust, and meat.
Food poisoning from C. perfringens
occurs throughout the world.
Most of the food poisoning is from
contaminated beef, gravy, and other meat products.
For example, a large piece of meat that
is slowly cooling often has an internal temperature in the range of 43
to 47C optimal for the growth of C. perfringens.
Heating the meat drives out enough air
to make it anaerobic, a condition that is conducive to growth but not
to sporulation.
Thus the contaminated meat contains the
vegetative clostridia, but little preformed enterotoxin. ( This
contrasts with the situation in botulism, in which preformed
neurotoxin of C botulinum is ingested. )
When contaminated food is consumed, the
ingested C. perfringens reach the intestine, where alfa-enterotoxin is
produced during sporulation.
Symptoms may develop within 2 to
4 hours, but 8 to 12 hours is usual.
Symptoms include cramping
abdominal pain, sudden vomiting, and frequent episodes of watery
diarrhea.
The effect of the toxin appears to be
greatest in the ileum. The patient usually recovers within 2 days.
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