In the treatment of tetanus, which is used as passive immunotherapy to neutralize circulating toxin?

• A. Tetanus vaccine
• B. Antibiotics
• C. Diphtheria toxoid
• D. Tetanus immune globulin

Answer: (D)

The main idea here is neutralizing circulating toxin with preformed antibodies. Tetanus immune globulin provides those antibodies that bind the tetanus toxin in the bloodstream, preventing it from attaching to nerve terminals and causing the characteristic muscle rigidity and spasms. This immediate, short-term protection is what we call passive immunotherapy, and it’s used right away in active tetanus cases to curb ongoing toxin effects.

Why this is the best choice: other options don’t provide that rapid toxin neutralization. The tetanus vaccine is a toxoid vaccine given to build future immunity, not to stop an existing infection — it takes time for the body to develop protective antibodies. Diphtheria toxoid is for diphtheria vaccination, not tetanus. Antibiotics help by killing the bacteria and reducing toxin production, but they don’t remove toxin already circulating in the body. They’re important as part of treatment, yet they don’t substitute for the immediate toxin-neutralizing effect of TIG.