What does the Elek test detect?

The Elek test is specifically designed to detect the presence of the diphtheria toxin produced by Corynebacterium diphtheriae in vitro. This test involves the use of a specific medium where C. diphtheriae can grow, and its toxin can be evaluated through immunodiffusion. When the specific antitoxin is introduced, a precipitin line forms if the toxin is present, indicating a positive result for toxin production by the bacteria.

In this context, it is crucial to note that the test is performed in a controlled laboratory setting (in vitro), distinguishing it from other methods that may assess toxin effects in living organisms (in vivo). The other options pertain to different bacterial species and their specific toxins, which are not detected by the Elek test, further emphasizing the appropriateness of the correct choice within the context of detecting diphtheria toxin specifically.