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Botulism is a
rare disease with 4 naturally occurring syndromes:
foodborne botulism
is caused by ingestion of foods contaminated with botulinum toxin (potent exotoxin produced by Clostridium botulinum
,
wound botulism
is caused by Clostridium botulinum colonization of a wound and in situ
toxin production,
infant botulism
is caused by intestinal colonization and toxin production, and
adult
intestinal toxemia botulism
is an even rarer form of intestinal colonization and toxin production
in adults.
Inhalational botulism
could result from aerosolization of botulinum toxin, and
iatrogenic
botulism
can result from injection of toxin.
Clostridium botulinum, is a soil anaerobe
which is common throughout the world, particularly in the west.
Botulism is characterized by a
symmetric descending paralysis of cranial nerves, limbs and trunk.
Botulism
from contaminated food:
Contamination of foodstuffs, especially
vegetables, by the organism is therefore relatively common.
Spores of C. botulinum withstand dry
heat as high as 180C for as long as 15 minutes and 100 C for hours.
If proper precautions are not taken in
the preservation of food, conditions favorable to germination,
proliferation, and toxin production by the organisms may be
established.
Inadequate heating during processing,
in fact, favours the growth of this organism by killing other bacteria
that are less heat resistant and that cannot therefore overgrow and
inhibit C. botulinum.
Destruction of other organisms also
prevents obvious warning features of spoilage such as bad odour and
color.
Most cases of botulism result from the
ingestion of home-processed vegetables, especially nonacid ones such
as beans or corn. In some countries cases result from contamination of
preserved meat such as ham and sausage (Latin botulus, "sausage").
Botulism related to commercially
processed food is rare. Its epidemiology may be difficult to elicit
because of the wide distribution of processed foods.
Wound Botulism
:
Wound botulism is
a rare infectious disease due to neurotoxin release from the
anaerobic, spore-forming bacterium Clostridium botulinum that is
becoming an ever more frequent complication of parenteral drug abuse
in the Western world.
It
is important that emergency clinicians are aware of the possibility of
wound botulism in parenteral drug users that present with unusual
neurological or respiratory symptomatology.
Rarely, systemic botulism follows
infections of wounds by toxigenic C. botulinum.
Botulism in
infants:
The rare occurrence of botulism in
infants constitutes an exception to the generalization that botulism
results from ingestion or rarely absorption of preformed toxin.
In infants, ingested spores of C.
botulinum may germinate in the intestine and elaborate toxin, which
gives rise to symptoms such as those of a hypotonic infant (“floppy
baby”).
Infant botulism exceptionally has been
incriminated as cause of the sudden infant death syndrome.
Botulinus
toxin:
Botulinus toxin is the most potent of
all bacterial toxins. Because it resists destruction by proteolytic
enzyme, it remains effective when ingested.
Six types of botulinus toxin have been
identified.
Four are responsible for human disease.
Type A , the most potent, carries a
mortality of approximately 75%, and type B a mortality of
approximately 20%.
Effects of
Botulinus toxin:
The promtness of onset of the symptoms
depends on dose, usually beginning between 12 to 36 hours after
ingestion, rarely as little as 3 to 4 hours.
Nausea and vomiting, sometimes with a
sense of abdominal distress but no real pain, are observed early.
Diplopia and difficulty in swallowing
are usually the first features of the characteristic paralyses
produced by the toxin.
Paralyses of pharyngeal muscles leads
to regurgitation of ingested food and liquids through the nose.
This often causes aspiration pneumonia.
The patient may be unable to hold the
head erect because of involvement of the neck muscles.
Death, if it occurs, usually results
from respiratory failure.
Specific antitoxin is the only
therapeutic measure available and is of value only early.
The toxin is bound to neural tissues
once the disease becomes established and in those sites can no longer
be neutralized by specific antitoxin.
 Botulinus toxin acts something like
curare, affecting principally the end plates of nerves and
specifically the myoneural junctions of the motor apparatus.
The toxin binds to membrane
receptors of the the synaptic vesicles and inhibits release of
acetylcholine, thus causing paralysis and respiratory failure.
No morphologic changes occur that are
specific for botulism. There may be petechiae and ecchymoses on serous
surfaces and the in central nervous system as secondary effects of
anoxia. There may be minute thromboses of small vessels, primarily in
the brain and brain stem.
The specific diagnosis depends on the
demonstration of an antitoxin-neutralizable paralysis in rodents
injected with the suspected food material or even with a sample of
the patients blood.
Treatment:
The
mainstays of therapy are meticulous intensive care (including
mechanical ventilation, when necessary) and timely treatment with
antitoxin.
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Summary: Botulism is
both an old and an emerging disease. Over 100 years ago, the
classic food-borne type was found to be caused by ingesting
contaminated food containing the toxin produced by a bacteria. In
the first half of the 20th century a second form, wound botulism,
was discovered. Three additional forms (infant, hidden, and
inadvertent) were first described in the last quarter of the 20th
century. Our understanding of how botulinum toxin blocks the
release of acetylcholine at the neuromuscular junction has been
clarified in the past 10 years. In the past 20 years, we have
witnessed one of the strangest of all ironies in the history of
medicine. The very lethal botulinum toxin is now being used as a
treatment in an expanding list of disorders. Research is advancing
in several directions. These new avenues include improved methods
of preventing and treating botulism and additional novel uses of
botulinum toxin as a therapeutic agent.
Botulism:
update and review.Semin
Neurol. 2004 Jun;24(2):155-63 |
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