The causative agent of malignant pustule is which organism?

The causative agent of malignant pustule is which organism?

• A. Corynebacterium ulcerans
• B. Bacillus anthracis
• C. Erysipelothrix rhusiopathiae
• D. Listeria monocytogenes

Answer: (B)

Malignant pustule is the skin form of anthrax. It is caused by Bacillus anthracis, a large, Gram-positive, spore-forming bacillus. When spores enter the skin, they germinate and release toxins that cause tissue necrosis, producing a characteristic painless papule that rapidly becomes a black eschar with surrounding edema—the malignant pustule. The organism’s capsule helps it evade the immune system, contributing to its virulence. The other organisms listed are associated with different infections (for example, some cause diphtheria-like illness, erysipeloid, or listeriosis), so Bacillus anthracis best fits the description of malignant pustule.

Malignant pustule is the skin form of anthrax. It is caused by Bacillus anthracis, a large, Gram-positive, spore-forming bacillus. When spores enter the skin, they germinate and release toxins that cause tissue necrosis, producing a characteristic painless papule that rapidly becomes a black eschar with surrounding edema—the malignant pustule. The organism’s capsule helps it evade the immune system, contributing to its virulence. The other organisms listed are associated with different infections (for example, some cause diphtheria-like illness, erysipeloid, or listeriosis), so Bacillus anthracis best fits the description of malignant pustule.