Differences between Anthrax bacilli and Anthracoid bacilli

 

Differences between Anthrax bacilli and Anthracoid bacilli

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S.N.	Character	Anthrax bacilli	Anthracoid bacilli
1.	Known as	Bacillus anthracis	B. anthracis similis, B. pseudo-anthracis or “anthrax-like” bacilli and Pseudoanthrax.
2.	Shape (Chain Length)	In long chains	In short chains
3.	Position of spores	Central, do not bulge the bacilli.	Central, subterminal or terminal, may bulge the bacilli.
4.	Capsule	Present	Absent
5.	Motility	Non-motile	Motile
6.	Under lower power microscope	Medusa head colony seen	Not seen
7.	Oxygen requirement	Strict aerobe	Aerobic or facultative anaerobic
8.	Growth at 45°C	No Growth	Growth usually seen
9.	Blood Agar	No hemolysis (or weak)	Hemolytic colonies(usually well marked)
10.	Turbidity	No Turbidity in broth	Turbidity seen usually
11.	Solid medium with penicillin	String of pearls appearance	No growth
12.	Gelatin stab agar	Inverted fir tree appearance	Absent
13.	In nutrient broth	Fluffy Cotton wool without pellicle	Turbidity and pellicle formation but no fluffy Cotton wool
14.	Salicin Fermentation	Negative	Usually Positive
15.	Rate of gelatin liquefaction	Slow	Rapid
16.	Lecithinase activity on egg yolk agar	— weak	+ marked
17.	Reduction of methylene blue in milk	Reduce methylene blue slowly	Rapidly reduce methylene blue

18.	Chloral Hydrate	Growth inhibited by  Chloral Hydrate	Not Inhibited
19.	Susceptibility to Gamma Phage	Susceptible	Not susceptible
20.	Penicillin sensitivity 10 unit disc	Susceptible	Resistant
21.	Pathogens	Pathogenic	Except B. cereus, most of them are non-pathogenic or opportunistic pathogens with low virulence.
22.	Diseases caused	■ Cutaneous anthrax  ■ Gastrointestinal anthrax  ■ Inhalational anthrax  ■ Anthrax meningitis.	■ Bacillus cereus is the most important pathogen causing GI infection, ocular infections, and catheter-related infections. ■ Bacillus subtilis may act as an opportunistic pathogen, causing eye infections and septicemia. ■ Bacillus licheniformis has also been incriminated in patients with food poisoning.
23.	Pathogenicity for mice or guinea pigs	Pathogenic (death in 24 – 48 hours)	No death
24.	Contaminants	Not a common contaminant.	Common contaminants in laboratory cultures.
25.	Organism(s)	Bacillus anthracis	B. cereus, B. subtilis, B. licheniformis, B. stearothermophilus etc.