(Clostridium botulinum)
Botulism is
a neuroparalytic disorder that can be classified into the following
categories: foodborne ,infant, wound, and undetermined .
The latter occurs in persons older than 12
months of age in whom no food or wound source is implicated.Except
for infant botulism, onset of symptoms occurs abruptly within a few
hours or evolves gradually over several
days.Symmetric,descending,flaccid paralysis occurs,typically
involving the bulbar musculature initially and later affecting the
somatic musculature.Symmetric paralysis may progress
rapidly.Patients with rapidly evolving illness may have generalized
weakness and hypotonia initially.
Signs and symptoms in older children or
adults can include diplopia, blurred vision,Dry mouth, dysphagia,
dysphonia, and dysarthria. Classically, infant botulism, which
occurs predominantly in infants younger than 6 months of age, is
preceded by constipation and is manifest as lethargy, poor feeding,
weak cry, diminished gag reflex, subtle ocular palsies, and
generalized weakness and hypotonia(eg, “floppy infant”).
A specturm of disease ranging from rapidly
progressive (eg,apnea, sudden infant death) to mild (eg,
constipation, slow feeding) exists.
Seven antigenic toxin
types of Clostridium botulinum have been identified. Human botulism
almost always is caused by neurotoxins A, B, E, and F. Types C and D
are associated primarily with botulism in birds and mammals. Almost
all cases of infant botulism are caused by types A and B.
Foodborne botulism
(median annual cases, 24 ) results when a food contaminated with
spores of C botulinum is preserved or stored improperly under
anaerobic conditions that permit germination, multiplication, and
toxin production. Restaurant –associated outbreaks from foods such
as patty-melts, potato salad, and aluminum foil-wrapped baked
potatoes illustrate that not all foodborne botulism results from
ingestion of improperly prepared home-canned foods, bottled garlic,
and cheese sauce.Illness occurs when the unheated or incompletely
reheated food is eaten and preformed botulinum toxin is
ingested.Foodborne botulism rarely occurs in infants or children
because they are less likely to be exposed to foods that might
contain botulinum toxin. Botulism is not transmitted from person to
person.
Infant botulism (media annual cases,71) results after ingested spores of C
botulinum or related species germinate, multiply, and produce
botulinum toxin in the intestine, probably through a mechanism of
transient permissiveness of the intestinal microflora . In most
cases of infant botulism , the source of spores is not identified
(and may be airborne from soil or dust ), but honey that has not
been certified to be gree of C botulinum spores is an identified and
avoidable source.
Light and dark corn syrups are not
sterilized when packaged, so they also may be contaminated by C
botulinum spores.Wound botulism results when C botulinum
grows in traumatized tissue and produces toxin. Accidental gross
trauma or crush injury may be a predisposing event, but during the
last decade, injection of contaminated black tar heroin has resulted
in the majority of cases.
Immunity to botulinum toxin dose not
develop in foodborne botulism, even after severe disease.
The usual incubation period for foodborne
botulism is 12 to 36 hours (range, 6 hours to 8 days ). For wound
botulism , it is 4 to 14 days between the time of injury and the
onset of synptoms. In infant botulism, the incubation period
is estmated at 3 to 30 days from the time of exposure to
spore-containing honey.
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A toxin
neutralization bioassay in mice* is used to identify botulinum toxin in
serum, stool, or suspect foods. Enriched and selective media are used to
culture C botulinum from stool and foods. In infant and wound botulism, the
diagnosis is made by demonstrating C botulinum organisms or toxin in feces or
wound exudate or tissue samples. Toxin has been demonstrated in serum in
approximately 1% of infants with botulism. To increase likelihood of diagnosis,
both serum and stool should be obtained from all persons with suspected
botulism. In foodborne cases, serum speciments collected more than 3 days after
ingestion of toxin usually are negative, at which time stool and gastric
aspirates are the best diagnostic speciments for culture.Since obtaining a stool
specimen may be difficult because of constipation, an enema using sterile
nonbacteriostatic water can be given.
The most prominent electromyographic
finding is and incremental increase of evoked muscle potentials at
high-frequency nerve stimulation (20-50 Hz). In addition, a characteristic
pattern of brief, small-amplitude, overly abundant motor action potentials can
be seen.
Meticulous Supportive Care.
The
most important aspect of therapy in all forms of botulism is meticulous
supportive care, particularly respiratory and nutritional.
Antitoxin. A
5-year, randomized
double-blind,placebo-controlled treatment trial of human-derived botulinum
antitoxin (formally known as botulinum immuneglobulin [BIG]) in infant botulism
showed a significant reduction in hospital days, mechanical ventilation, and
tube feedings in BIG recipients and a $70 000 reduction in hospital cost per
case. The California Department of Health Services (24-hour telephone number,
510-540-2646) should be contacted about procurement of BIG.
Treament with BIG should be started as
early in the illness as possible and should not be delayed while awaiting
laboratory confirmation. Equine botulium antitoxin also is obtainable and can be
administered to adults after testing for hypersensitivity to equine sera if BIG
is not available. Approximately 9% of treated persons experience some degree of
hypersensitivity reaction to equine sera. Trivalent antitoxin (types A, B, and
E) and bivalent autotoxin (types A and B) can be obtained from
*For information ,
consult your state health department.
The Centers for Disease Control and Prevention (CDC) through state health
departments. If contact cannot be made with the state health department, the CDC
Drug Service should be contacted (see Appendix I,Directory of Resources ,p 743).
Antimicrobial Agents. In infant
botulism, antibiotics are used only to treat secondary infections because Iysis
of interluminal C botulinum could increase the amount of toxin available for
absorption. Aminoglycosides can potentiate the paralytic effects of the toxin
and should be avoided.
Standard precautions are recommended.
 Prophylactic
equine antitoxin for asymptomatic persons who have ingested a food known to
contain botulinum toxin is not recommended. Because of the danger of
hypersensitivity reactions , the decision to administer antitoxin requires
careful consideration.Consultation about antitoxin use may be obtained from the
state health department or the CDC.
Elimination of ingested toxin may be facilitated by inducing
vomiting and by gastric lavage, rapid purgation, and high enemas. These measures
should not be used in infant botulism . Enemas should not be administered to
persons with illness except to obtain a stool specimen for diagnostic purposes.Exposed persons should have close medical observation.
Although most sources of spores for infant botulism are
unavoidable , honey should not be given to children younger than 12 months of
age.
Contacts of persons with wound or infant botulinum are not at an
increased risk of acquiring botulism.Botulinum toxoid (types A, B, C, D, and E )
is available from the CDC for immunization of laboratory workers whose regular
exposure places them at high risk.
Education to improve home-canning methods should be promoted,
but cases also may be restaurant-acquired.Use of a pressure cooker (at 116C
[240.8 F] ) is necessary to kill spores of C botulinum.Boiling for 10 ,minutes
will destoy the toxin.Time-temperature-pressure requirements very with the
product begin heated.In addition, food containers that appear to bulge may
contain gas produced by C botulinum and should be discarded.Other foods that
appear to be spoiled should not be tasted.Cases of suspected botulism should be
reported immediately to local and state health departments.
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