Smears stained with methylene blue or one of the special stains(Neisser's or Albe's )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 Loeffler's 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 panicker's; 10th edition; Page no: 242