This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
[{'content': 'True statement regarding diptheria is : \nSelect and explain. \nA. It can be diagnosed by demonstration of antibodies by ELISA, B. Immunization prevents carriers state, C. Treatment of contacts is not indicated, D. Iron has critical value in the production of toxin', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Diagnosis of Diptheria\ni. Isolation by culture :\nSwabs are inoculated on :\n– Loeffler’s serum slope (growth is rapid) : for rapid diagnosis.\n– Tellurite blood agar (growth is delayed but it is particularly important in isolation of bacilli from convalescent, contacts, carriers) : Selective media.\n– Blood agar (for differentiating staphylococcal and streptococal pharyngitis). convalescent, contacts, carriers) : Selective media.\n– Blood agar (for differentiating staphylococcal and streptococal pharyngitis).\nii. Demonstration of toxicity of isolated strain :\nIn vivo test – done by infected broth emulsion of culture subacutaneously and intracutaneously into guinea pigs.\nIn vitro test – Elek’s gel precipitation test and tissue culture test on agar overlay of cell culture monolayer.\nControl of Diptheria\ni. Cases – Antitoxin + penicillin or erythromycin\nPark 19/e, p 137\nii. Carriers – Erythromycin\niii. Contacts –\na. When primary immunization or booster dose was received within the previous 2 years.\n\nNo further treatment.\n\nb. When primary immunization or booster dose was received more than 2 years ago.\n\nOnly a booster dose of diphtheria toxoid.\n\nc. Non immunized close contacts :\n\nProphylatic penicillin or erythromycin\n1000 - 2000 units of diphtheria antitoxin\nActive immunization against diphtheria.\n\niv. Community – Only effective control is by active immunization with diphtheria toxoid of all infants with subsequent booster doses every 10 years thereafter.\nRemember : Vaccine ‘being a toxoid’ is not directed against organism and hence immunization does not prevent carrier state which is due to organism not due to toxin.', 'role': 'assistant'}]