<prompt> Drug of choice for prophylaxis in diphtheria is:ErythromycinDoxycyclineTetracyclineClindamycin  <response>: The options for chemoprophylaxis of diphtheria include Erythromycin 7-10 days oral course or Benzathine Penicillin G single intramucular dose. Ref: Erythromycin: A motilin Agonist and Gastrointestinal Prokinetic Agent: American Journal of Gastroenterology 88 4: 485-90; Basic and Clinical Pharmacology By Katzung, 9th Edition, Section VIII; Parks Textbook of Preventive and Social Medicine By K. Park, 18th Edition, Page 104 and 19th Edition, Page 893 