Elek's gel precipitation test used for diagnosing:: (A) Corynebacterium Jakeium, (B) Corynebacterium diphtheriae, (C) Clostridium tetani, (D) Clostridium perfringens
Answer is B. Elek's gel precipitation test is an example of double diffusion in two dimensions. It is used to demonstrate C. dipthariae. Precipitation band: If the strain is toxigenic, the toxin diffuses in the agar, meets with the antitoxin and produces arrow-shaped precipitation band. Nontoxigenic stain will not produce any precipitation line. The precipitate lines would fuse with each other if the toxins produced by die strains are identical.