Immunologic evidence of group A streptococcal infection in patients undergoing mitral commissurotomy.

Serum levels of 3 group A streptococcal antibodies were determined in 53 patients prior to mitral commissurotomy and monthly for 3 to 6 months postoperatively. Significant elevation of antibody titers was relatively infrequent prior to commissurotomy and the presence of chronic productive inflammatory lesions in the biopsied atrial appendage was usually unrelated to recent streptococcal infection. The "postcommissurotomy syndrome" also occurred in some patients without evidence of such infection. Postoperative subclinical streptococcus infection occurred frequently enough, however, to suggest the need for vigorous preoperative penicillin therapy and careful postoperative prophylaxis.