A controlled study of the effects of penicillin on 165 patients with acute rheumatic fever has failed to demonstrate any alteration, attributable to the antibiotic, in valvular sequelae. The results suggest that the Streptococcus in the bacterial form does not play a continuing role in an acute episode of rheumatic fever once rheumatic symptoms have appeared.
Samuel VB, Julio GL, Alberto VI, Enrique CT, Augusto SC, Mortimer EA, Rammelkamp CH. Failure of Penicillin to Alter Acute Rheumatic Valvulitis. JAMA. 1965;194(12):1284-1286. doi:10.1001/jama.1965.03090250018003