Chapter 6: Gram-positive Bacteria: Spore-forming rods: Bacillus and Clostridium Flashcards
What is the Gram stain and morphology of Bacillus?
Gram-positive
spore-forming
rods
What are the two Gram-positive spore-forming rods?
Bacillus
Clostridium
What is the Gram stain and morphology of Clostridium?
Gram-positive spore-forming rods
What type of metabolism does Bacillus exhibit?
aerobic
What type of metabolism does Clostridium exhibit?
anaerobic
like in a closet
How do Bacillus and Clostridium differ biochemically to oxygen?
Bacillus is aerobic.
Clostridium is anaerobic.
How do Bacillus and Clostridium cause disease?
By the release of potent exotoxins
What bacterium causes the disease anthrax?
Bacillus anthracis
What are the two pathogenic species of Gram-positive aerobic spore-forming rods?
Bacillus anthracis
Bacillus cereus
Bacillus anthracis - Gram stain
Gram-positive
Bacillus anthracis - morphology
rods
Bacillus anthracis - spores-forming?
yes
Bacillus anthracis - motility?
non-motile
Bacillus anthracis - capsule?
encapsulated (poly-D-glutamic acid; only one with protein capsule)
Bacillus anthracis - metabolism?
aerobic
What is the only bacterium with a capsule composed of protein?
Bacillus anthracis
Bacillus anthracis has a capsule composed of what?
protein - poly-D glutamic acid
How does the Bacillus anthracis capsule act as a virulence factor?
It prevents phagocytosis by macrophages.
How is Bacillus anthracis transmitted? (3)
skin contact
inhalation
ingestion of spores (from contaminated meat)
What population is particularly vulnerable to Bacillus anthracis infection?
individuals exposed to infected herbivores (cows and sheep) or soil, their skins (hides or wool), or their carcasses
Can Bacillus anthracis be transmitted from human to human?
No, it has never been reported. Infection only occurs when humans are exposed to the spores during direct contact with infected animals or soil.
Where are Bacillus anthracis spores present?
in dry soil, and in the GI tract of infected animals (zoonotic herbivores: sheep, goats, cattle)
What are the 3 forms of anthrax? (related to modes of transmission)
1) cutaneous anthrax
2) respiratory anthrax
3) GI anthrax
How does cutaneous anthrax present?
painless necrotic pustules - round black lesion (boil-like): ulcer with black eschar, often with a rim of edema of surrounding tissue.
Uncommonly progresses to bacteremia and death