Which organism among the following is not commonly associated with gas gangrene?

• A. difficile
• B. perfringens
• C. sordellii
• D. novyi

Answer: (A)

Gas gangrene is a rapidly spreading, gas-forming infection of muscle tissue caused by anaerobic Clostridium species that invade damaged soft tissue and release powerful toxins. The usual culprits are Clostridium perfringens, which produces the alpha toxin that damages cell membranes and drives myonecrosis, along with other gas-forming relatives such as Clostridium sordellii and Clostridium novyi. Clostridium difficile, in contrast, is primarily an intestinal pathogen that causes antibiotic-associated colitis through its toxins A and B, and it does not typically cause soft-tissue gas gangrene. So, the organism not commonly associated with gas gangrene is Clostridium difficile.