<prompt> In a completely and adequately immunized child against Diphtheria, the throat swab was collected. It showed the presence of Corynebacterium diphtheriae like organisms on Albe staining. These organisms can have one of the following propeies on fuher laboratory processingIt can grow on Potassium tellurite mediumPositive Eleks gel precipitation testIt can be pathogenic to experimental guinea pigsIt can produce cytotoxicity in tissue cultures  <response>: Smears stained with methylene blue or one of the special stainsNeissers or Albes will show the bacilli with metachromatic granules. Albes stain may show delicate green bacilli with purple-blue metachromatic granules. For culture, the swabs are inoculated on Loefflers serum slope, tellurite blood agar and a plate of ordinary blood agar, the last for differentiating streptococcal or staphylococcal pharyngitis, which may stimulate diphtheria. Tellurite medium is impoant in the isolation of diphtheria bacilli from convalescents, contacts and carriers as in these cases they may be outnumbered by other bacteria Reference: Textbook of Microbiology; Anathanarayan and panickers; 10th edition; Page no: 242 