<prompt> Answer this question truthfullyWhat is the name of the test that is used to distinguish between toxic and nontoxic strains of Corynebacterium diphtheriae?  <response>: <reason> The Eleks test is used to differentiate between toxic and nontoxic strains of Corynebacterium diphtheriae. This test detects the presence of diphtheria toxin produced by the bacteria. 