Which organism has a capsule composed of poly-D-glutamate and may cause Wool Sorters' disease?

• A. Meningococcus
• B. Gonococcus
• C. Clostridium tetani
• D. Bacillus anthracis

Answer: (D)

The key idea is that some bacteria have capsules with unusual chemical makeup that contribute to their ability to cause disease. Bacillus anthracis has a capsule made of poly-D-glutamic acid, a distinctive feature that helps it resist phagocytosis and thrive in the host. This organism is classically associated with anthrax, including the inhalational form once called Wool Sorters’ disease because exposure to contaminated animal wool or hides led to severe inhalation cases. Among the options, only Bacillus anthracis has this poly-D-glutamate capsule, whereas the other organisms have different capsule types (or none) and are not tied to this specific capsule structure.