Term
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Definition
a genus of aerobic or facultatively anaerobic endospore-forming, gram-positive bacilli that occur singly, in pairs or
in chains. There currently are about 70 species
The most important pathogens in the genus are Bacillus
anthracis and Bacillus cereus. |
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Term
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Definition
Is acquired by skin contact
with B. anthracis endospores.
2. The spores enter small cuts in
1. Is acquired by ingesting B. anthracis endospores. It is
rare in humans, but common in herbivores.
A. Herbivores acquire gastrointestinal anthrax by ingesting B.
anthracis endospores while eating grass that is growing on
soil contaminated with B. anthracis.
B. B. anthracis is naturally present in soil in many parts of
the world. Infected animals contaminate soil with large
skin, germinate and multiply
at the site of entry.
3. A*papule* develops at the entry
site in 12-36 hours. It rapidly
develops into a *pustule* that
forms a *necrotic black scab
called an eschar* |
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Term
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Definition
inhalation of B. anthracis endospores
humans usually acquire
it by handling B. anthracis endospore
contaminated wool, hides or hair. |
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Term
| C. perfringens Food Poisoning |
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Definition
characterized by abdominal cramps & watery diarrhea
2. Is associated with homemade meat stews and chili. |
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Term
| Bacillus cereus food poisoning |
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Definition
emetic and diarrheal food poisoning
rice and bean dishes in Asian and Mexican restaurants, but can also occur with meat dishes |
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Term
| C. perfringens Gas Gangrene |
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Definition
endospores from the environment into the body by a
wound/injury that renders host tissue ischemic or necrotic.
germinate in the ischemic tissue and
cause a rapidly spreading anaerobic infection
The gases produced by clostridia cause infected tissue to
swell, rupture and ooze purulent, foul smelling fluids
Other clostridia besides C. perfringens can cause gas
gangrene, but perfringens is the most common cause. |
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Term
| pseudomembranous colitis, |
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Definition
hosts with C. Difficle infection characterized by the
some formation of ulcers in the colon that become covered by
a pseudomembrane of fibrin & dead cells.
vancomycin or metronidazole, |
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Term
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Definition
common cause of diarrhea in hosts
taking broad spectrum antibiotics. It is a major cause of
healthcare associated infections in the U.S.
produces 2 different cytotoxins that kill
mucosal epithelial cells, and cause diarrhea and
hemorrhagic lesions in mucous membranes in the colon
opportunistic pathogen that can grow to high
numbers in hosts being treated with broad-spectrum
antibiotics that suppress the normal flora
can develop several months after an antibiotic is taken.
Some hosts develop recurring bloody diarrhea and
pseudomembranous colitis, which is characterized by the
formation of ulcers in the colon
Minor C. difficle infections usually resolve on their own
if the antibiotic causing the diarrhea is discontinued.
B. Pseudomembranous colitis is treated with vancomycin or
metronidazole, & feces transplantation in resistant cases. |
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Term
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Definition
highly fatal disease botulism
botulinum produces a potent neurotoxin called
botulinum toxin that causes botulism.
A. Botulinum toxin is a protein.
B. There are 7 antigenically distinct types designated A to
G that are produced by different C. botulinum strains.
C. The 7 botulinum toxins are among the deadliest known toxins.
Botulinum toxins enter motor neurons and bind
irreversibly to their cytoplasmic membrane at
neuromuscular junctions, blocking the release of
acetylcholine from the neurons,
Inhibition of acetycholine release from neurons prevents
muscle from contracting & produces a flaccid paralysis |
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Term
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Definition
C. botulinum endospores commonly contaminate vegetables, meat, fish and honey.
The endospores are resistant to killing and survive in
these foods if they are inadequately processed
during canning or other preservation methods.
A. The surviving C. botulinum spores germinate in the
anaerobic environment of canned/processed food, C. bot
multiplies and intoxicates the food with botulinum toxin.
B. Hosts who ingest the intoxicated food will get botulism.
C. The symptoms of botulism begin 18-24 hours after eating
intoxicated food and include blurred vision, weakness,
difficulty swallowing and talking, and constipation.
The foods most at risk for food-borne botulism are non-
acidic canned foods like green beans, peas and corn,
processed meats, fish, and dairy products.
B. C. botulinum cannot grow in acidic foods (pH < 4.5) or
under aerobic conditions.
C. Nitrites inhibit the growth of C. botulinum and are
commonly used to prevent the growth of C. botulinum in
processed meats like hot dogs, sausages and lunch meats. |
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Term
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Definition
by the ingestion of C. botulinum
endospores by infants.
The C. botulinum endospores germinate in the large
intestine of the infants.
B. C. botulinum multiplies in their large intestine and
secretes botulinum toxin which is absorbed into their
body and causes botulism.
C. This type of botulism is rare in anyone >9 months of
age because C. botulinum is unable to establish itself in
the intestine of hosts with a developed normal flora
because it cannot compete with normal intestinal flora.
constant
crying, constipation, failure to thrive and limpness
(paralysis). The death rate in treated infants is 3%.
*Honey* is the food most
commonly linked to
infant botulism |
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Term
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Definition
Botulinum toxin type A can be used to prevent
unwanted muscle contractions in some diseases
prevent wrinkles in skin and sweating. |
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Term
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Definition
initial symptoms of tetanus are tightening of the
muscles in the jaw and neck, and drooling. The jaw
and neck muscles cannot be relaxed, which is why
tetanus is commonly called lockjaw |
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Term
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Definition
Clostridium tetani
1. Is a small motile, anaerobic, gram-positive rod
that forms terminal endospores and causes the
highly fatal disease tetanus.
Virulence Factors of C. tetani
1. C. tetani produces a potent neurotoxin called
tetanus toxin that causes tetanus.
A. Tetanus toxin is a protein composed of 2 polypeptide
chains. There is only 1 antigenic type.
B. The gene for tetanus toxin is carried on a plasmid.
Tetanus toxin binds to motor nerve cells, enters
them, and is transported to the central nervous
system where it enters an inhibitory neuron.
2. In inhibitory neurons, tetanus toxin blocks the
release of inhibitory neurotransmitters that cause
a muscle to relax.
3. Muscles affected by tetanus toxin are unable to
relax. They contract (sometimes violently) and
stay contracted. |
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