Bacillus Flashcards
1
Q
What is Bacillus?
A
- Gram positive rods
- Spore-forming
- Several species
- Most are nonpathogenic (saprophytic)
2
Q
What is Bacillus anthracis?
A
- Gram Positive Rods
- long chains in culture
- Short chains in tissue
- Central Spores
- Capsule
- First bacterium shon to cause disease
- Rober Koch in 1877
- Koch’s postulates
3
Q
What are the Bacillus anthracis spores?
A
- Formed when cells are exposed to air
- Rarely in blood and tissues
- High CO2 inhibits sporulation
- Spores are highly resistant
- Can remain dormant for decades
4
Q
What are B. cereus and B. licheniformis?
A
- No invasive ability but grow in tissues weakened by injury
- Mastitis in cows and abscesses in animals
- B. cereus - food borne intoxication
5
Q
What is B. cereus?
A
- Normal soil bacterium
- also in grains and spices
- Food borne intoxications
-
Emetic Form:
- Incubation period of 1 - 6 h
- Nausea, vomiting, and abdominal cramps
- Heat stable enterotoxin (5 KDa)
-
Diarrheal Form:
- Incubation period of 8 - 16 h
- Abdominal cramps and diarrhea
- Heat labile enterotoxin (50 KDa)
6
Q
What is the colony morphology of Bacillus anthracis?
A
- Nonhemolytic
- Ground Glass appearance
- Medusa Head
7
Q
What are the Types of Bacillus anthracis?
A
- Types A - Worldwide
- Strains:
- Sterne - Avirulent, used for vaccine
- Vollum - virulent
- Ames - virulent
- Strains:
- Type B - Southern Africa
8
Q
What are the Virulence Factors of Bacillus anthracis?
A
- Capsule
- Exotoxins
- pXO2
- Codes for capsule
- Prevents phagocytosis
- pXO1
- Codes for:
- Protective antigen (PA)
- Edema Factor (EF)
- Lethal Factor (LF)
- Cytotoxicity and cell death
- Codes for:
- pXO2
9
Q
What are the Tripartite toxins of Bacillus anthracis?
A
-
EdTx: Edema factor and Protectie antigen
- Adenylate cyclase enzyme
- Increases cAMP → edema
-
LeTx: Lethal factor and protective antigen
- Zn metalloprotease
- Protective antigen facilitates entry of edem and lethal factor into the target cells
10
Q
What is the Capsule of Bacillus anthracis?
A
- Encoded by pXO2
- Poly D-glutamic acid
- The negative charge on the capsule inhibits phagocytosis of the vegetative cells
- Sterne strain is noncapsulated
11
Q
What is the mode of infection of Bacillus anthracis?
A
- Ingestion or Inhalation of spores
- Contaminated feed (Bone meal) and water
- Skin infection
12
Q
What is the pathogenesis of Bacillus anthracis
A
- Massive bacteremia
- Systemic signs of anthrax
- Death
- 80% of the organisms in blood and 20% in spleen
13
Q
What is Anthrax in Animals?
A
- Cattle, sheep, and goats are most susceptible
- Horses intermediat susceptibility
- Pig and dogs are generally resistant
- Wild ruminants are susceptible
- Lab animals - Guinea pigs
14
Q
What is anthrax in Ruminants?
A
- Usually acute
- High fever with death in 1 - 2 days
- Dead animals will have blood exuding from orifices
- Necropsy is not recommened
- Spleen is enlarged, dark, and exudes thick, black colored blood when cut
- Enlarged lymph nodes
15
Q
What is Anthrax in horses?
A
- Generally acute
- Death in 1 - 3 days
18
Q
How is Bacillus anthracis Diagnosed?
A
- Suspected based on clinical signs, pathological findings, and epidemiological data
- Occurs in an area in systemic cyclicity
- Only in a few animals, generally in summer following wet spring
- Suspected cases reported immediately to state public health officials
- Premise should be quarantined
- Blood sample (ear vein) or swabs of exuding blood or edematous lesions for microscopic examination
- String of Pearls
- Fluorescent antibody technique to demonstrate capsule
- PCR for virulence genes
22
Q
What is cutaneous anthrax?
A
- Most common
- Head, neck, hands, legs
- Skin break
- spores enter and germinate
- Skin lesion: itchy redness to dark blister to black eshcar
