<prompt> A child was diagnosed of having rheumatic fever. She is allergic to penicillin. Which of the following agent can be used for secondary prophylaxis in this child?ErythromycinClindamycinVancomycinGentamicin  <response>: The best antibiotic for secondary prophylaxis is benzathine penicillin G 1.2 million units, or 600,000 units if 27 kg delivered every 4 weeks. It can be given every 3 weeks, or even every 2 weeks, to persons considered to be at paicularly high risk. Oral penicillin V 250 mg can be given twice-daily instead but is somewhat less effective than benzathine penicillin G. Penicillin allergic patients can receive erythromycin 250 mg twice daily. Ref: Carapetis J.R. 2012. Chapter 322. Acute Rheumatic Fever. In D.L. Longo, A.S. Fauci, D.L. Kasper, S.L. Hauser, J.L. Jameson, J. Loscalzo Eds, Harrisons Principles of Internal Medicine, 18. 