Exam 2: Bacillus Flashcards by Anika Eidson

What are Bacillus spp.?

Large gram positive, aerobic or facultative anaerobic rods that produce endospores only under aerobic conditions

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What are Clostridium spp.?

Obligate anaerobic, large, gram positive rods that form endospores

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What can only spores of clostridium survive?

Oxygen

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What is the significance of B. anthracis?

Mammalian pathogen

Anthrax

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What is the significance of B. cereus?

Food poisoningm, gangreous bovine mastitis, supperative wound infections
Common soil saprophyte and lab contaminant

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What is the significance of B. larvae?

In apiculture

Bee foul brood

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What is the significance of B. thuringiensis?

Biologic insecticide
Produces insecticidal crystal protein
Exotoxin used in transgenic plants

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What is the significance of B. polymyxa?

Produces protein ionophore antibiotic

Polymyxin B.

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What is the significance of B. colistinus?

Produces protein ionophore antibiotic

Colistin

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What is the most significant pathogen of the genus in vet med?

B. anthracis

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What are the susceptible species (from most to least) to B. anthracis?

Cattle
Deer
Sheep
People
Goats
Horses
Swine
Dogs
Birds and poikilotherms are resistant

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What is the septicemic form of B. anthracis usually acquired through?

Inhalation

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How quickly can the septicemic form be fatal?

In 4 hours

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What form of B. anthracis do humans normally get?

Skin form, but they can also inhale

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What is the incubation period in humans before septicemia?

5-7 days

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Does human-to-human transmission occur?

Not as far as we know

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What form of B. anthracis can swine and strict carnivores acquire?

Oral/pharyngeal form

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What is the infections particle of B. anthracis?

Endospore (most resistant form of life)

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How can an endospore be killed?

Autoclave (121 degrees C, 15 psi, 15 min)*
Hot air oven
Formalin
Heat-fixed slides

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What happens to vegetative cells in unopened carcasses?

They are easily killed and die rapidly as this is an anerobic environment, but their spores will live on at air interfces

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What are the endemic areas of B. anthracis in order of most occurring?

Mississippi river delta
Texas gulf coast
SE South Dakota
NE Nebraska
Sacramento/San Joaquin Valleys
NW territory Great Slave Lake area

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What soils can B. anthracis be found in?

Alkaline soil
High N content
Soils rich in Ca and N

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How can B. anthracis be spread?

By periodic flooding

What must soil flora lack?

Certain Sterptomyctes spp.

When do spores form?

During dry periods

What contributes to epidemics?

Alternating wet and dry periods

In an outbreak, what are large numbers of B. anthracis shed through?

Animal amplification

What are the 6 primary forms of disease with B. anthracis?

``` Septicemic Cutaneous form Pharyngeal form Intestinal form Respiratory form Meningitis ```

Describe the septicemic form of disease

Herbivores: incubation of 3-7 days, fatal after 1-2 hours after first signs High fever, bleeding, more prolonged in horse than cow Horse and swine reported to have low number of organisms in circulation during septicemia

Describe the cutaneous form of disease

Intensely dark, relatively painless edematous eschar Ulcer with necrotic center (malignant carbuncle) May become septicemic, but heals rapidly with antibiotic therapy Reported in people, rabbits, swine, and horses

Describe the pharyngeal form of disease

Reported in swine, dogs, and cats Subacute to chronic carbuncular lesions of jowl and tongue Swelling of lips, head, and throat Severe gastroenteritis

Describe the intestinal form of disease

Reported in people, dogs, and cats | B. anthracis grows readily on cut surface of boiled veggies and sporation occurs

Describe the respiratory from of disease

In people, usually becomes septicemic and rapidly fatal

Describe the meningitis form of disease

CNS signs, only recognized in people | Rare

What is the pathogenesis of anthrax?

1. Ingestion, inhalation, skin exposure by spore contact 2. Poly-D-glutamate capsule 3. To be virulent, it requires 2 different plasmids (1 coding for capsule and 1 coding for toxins) 4. Sheer numbers of anthrax overwhelm spleen and a single, multicomponent protein exotoxin is produced

Describe Poly-D-glutamate capsule

Antiphagocytic Antiopsonic Nonimmunogenic Nonantigenic

What are the toxin actions from the exotoxin produced?

``` Damage/kill phagocytes Increase capillary permeability Prevent clotting Block opsonization Capillary thrombosis occurs BP falls Shock and death follow ```

What is the toxin a product of?

A 110 Mdal plasmid

What is this toxin specifically?

Tripartite subunit toxin (1 unit binds, 2 units are toxic)

What is the structure of the subunit toxin?

A:B structure (B binds and A is active)

Describe the toxin

``` Edema factor (EF) Protective antigen Lethal factor (LF) ```

What does edema factor affect?

Na/K pump

What does protective antigen do?

Binds to cell receptor and allows EF and LF to enter

Describe lethal factor

Dominant virulence factor | Cleaves and inactivates MAPKK1 and MAPKK2, which are enzymes in charge of cell growth

Why is it believed that birds are resistant to anthrax?

The toxin is not produced at 42 degrees C

What would you see from an animal that should make you think about anthrax?

Any sudden death with bleeding from all body openings, unclotted dark blood, delayed rigor mortis

Where should the blood sample for anthrax come from?

Jugular veins

Why should you be quick to bring back a sample on anthrax?

If the animal has been dead more than 1 hour, it is less likely to culture

Why should you not open a carcass believed to have anthrax?

Once exposed to air, spores will be released and infect

What stain smears for anthrax?

Wrights, giemsa, methylene blue, or gram stain

What is anthrax like in vivo?

A large blue bacilli, single or short chains, no spores usually

What are B. anthracis antigens demonstrated in extracts from contaminated products by?

Ascoli test

What is the treatment for anthrax?

Penicillin (cidal) or tetracycline (static), which are only effective early before lethal concentration of anthrax accumulates Penicillin resistant strains are isolated in Mississippi

What is the immunity to anthrax like?

Mainly humoral, antitoxic

Why is the sterne strain used mostly in US?

Has plasmid for toxins, but not for capsule

What is the vaccine available for people?

Alum-precipitate supernatant toxoid