Bacillus Anthrax

Ans. is ‘a’ i.e., Cause by gram positive bacilli; ‘b’ i.e., Soil reservoir

• All mammals are susceptible, though to a varying degree.
• In natural conditions both wild herbivores and domesticated animals are susceptible.

Ans. is ‘d’ i.e., Toxin is a complex of two fractions 

VIRULENCE FACTORS OFANTHIRA BACILLI

1)       Capsular polvpeptide  -inhibits phagocytosis – encoded by a plasmid

2)       Anthrax toxin

-is a complex of three fractions :

a) The edema factor (EF or factor I)

• It is an adenyl cyclase, leading to intracellular accumulation of cAMP
• Responsible for the edema

b) The protective antigen factor (PA or factor II)

• binds to the receptors on target cells
• antibody to PA is protective

c) The lethal factor (LF or factor III)

• Causes cell death
• Mechanism is not known

– Anthrax toxin is encoded by a separate plasmid.

About option b

. Cutaneous antrax generally resolves spontaneously, but 10-20% of untreated patients may develop fatal septicemia or meningitis.

Ans. is ‘c’ i.e., Non-motile 

.     Members of the genus bacillus, other than the anthrax bacillus are called as pseudoanthrax or anthracoid bacillus.

.   Most important anthracoid bacillus is B. cereus.

Differentiating features between anthrax and anthracoid bacilli (B. Cereus)

Anthrax bacilli                                                      Anthracoid bacilli

1. Nonmotile                                                                      Generally motile
2. Capsulated                                                                    Noncapsulated
3. Grow in long chains                                                      Grow in short chains
4. Medusa head colony                                                   Not present
5. No growth in penicillin agar                                        Grow usually (10 units/ml)
6. Hemolysis absent or weak                                          Usually well marked
7. 7.       Inverted fir tree growth and                                       Rapid liquefaction slow gelatin liquefaction
8. No turbidity in broth                                                    Turbidity usual
9. Salicin fermentation negative                                    Usually positive
10. No growth at 45°C                                                       Grows usually
11. Growth inhibited by chloral hydrate                         Not inhibited
12. Susceptible to gamma phage                                     Not susceptible
13. Pathogenic to laboratory animals                             Not pathogenic

Ans. is ‘a’ i.e., Bacillus anthrax 

Ans. is ‘All

Ans. is ‘a’ i.e., Anthrax 

Ans. is `b’ i.e., Anthrax

Selective media for B. antracis is PLET medium, consisting of polymyxin, lysozyme, ethylene diamine tetraacetic acid (EDTA) and thallous acetate added to heart infusion agar.

Ans. is ‘d’ i.e., Anthrax

BACILLUS ANTHRACIS

Morphology ‑

• Gram positive
• Non motile (all other members of genus Bacillus are motile)
• Arranged singly, in pairs or in short chains
• Capsulated – entire chain being surrounded by a capsule.

– Capsule is polypeptide

• Sporing – Spores are formed in culture or in soil but never in animal body during life. 
• Chain of bacilli presents a bamboo stick appearance.

Ans. b. Anthrax