Molecular Biology

Question:

A 12-year-old girl is admitted to the hospital because of marked shortness of breath, an erythematous rash, and painful, swollen hip and knee joints. She is agitated. A chest x-ray shows an enlarged heart and changes consistent with pulmonary edema. Intractable congestive heart failure develops, and she dies on the second hospital day. This child most likely had a recent history of which of the following?

Correct Answer: D.  Pharyngitis

This girl has severe carditis, which resulting enlargement of the cardiac shadow and acute congestive heart failure. This is a severe consequence of rheumatic fever, which is suggested by the acute-onset polyarthritis and rash (erythema marginatum). Rheumatic fever generally occurs 1-5 weeks after an upper respiratory infection caused by beta-hemolytic streptococcus. It is postulated that the immune system’s response to the strep results in attack also on native tissues with similar antigens (“molecular mimicry”).
Averting the possibility of rheumatic fever after streptococcus infection is the basis of penicillin treatment and prophylaxis for all people with suspected infection.