<prompt> Eleks gel precipitation test is done for:Corynebacterium diphtheriaSalmonella choleraesuisClostridium botulinumDiphtheroids  <response>: Eleks gel precipitation test is done for Corynebacterium diphtheriae. Detection of C. diphtheriae: Eleks gel precipitation test - Double diffusion in two dimensions Ouchterlony procedure, Detection of tox gene by PCR. Detection of diphtheria toxin by ELISA or immunochromatographic test ICT. Cytotoxicity produced on cell lines. 