Investigation of choice of diphtheria carrier is:

Ans. is 'a' i.e., Throat Swab CultureRef: Park, 24th/e. p. 536Carriers are detected by cultural methods - swabs are taken from nose and throat and it is examined by culture methods for diphtheria bacilli.Asymptomatic Carriers and Contacts: All carriers and contacts of persons carrying a toxigenic strain should receive antibiotic prophylaxis: Benzathine penicillin G (600,000 units for persons younger than 6 years old and 1,200,000 units for those 6 years old and older). OrA 7- to 10-day course of oral erythromycin (40mg/kg/day for children and 1g/day for adults). The immunization history of all exposed individuals should be established and updated. Immunized individuals receive a single reinforcing dose according to age. Patients should be kept under surveillance and antitoxin treatment should be given at first signs of illness.