Precipitin Formation in S. Viridans Subacute Endocarditis

Abstract

The sera of nineteen patients∗ with S. viridans sub-acute endocarditis have been studied for precipitins against protein fractions of S. hemolyticus, 1 S. viridans, 2 Staph, aureus, 2 and the group specific carbohydrate of S. hemolyticus. The S. viridans and Staph. aureus fractions were 5 and 7 years old, respectively, whereas the S. hemolyticus fractions were freshly prepared. All of the patients had the classical disease picture. Blood cultures were negative in 2 of the cases. These patients are to be studied further. The sera were collected at a time when the disease had been sufficiently advanced to justify the patient's admission to the hospital. On the basis of clinical history and the autopsy findings in some cases, 17 of the patients had rheumatic heart disease, and one of the remaining individuals had a normal heart at post-mortem, except for the fresh bacterial endocarditis.

The precipitin test was performed by adding 0.3 cc. of each serum to 0.3 cc. of the respective antigen and incubating the tubes in a water bath at 37°C. for 2 hours. The material was left in the icebox over night and the initial reading was made in the morning. The tubes were then centrifuged at 1700 revolutions per minute for 10 minutes and a second reading was made.

Table I shows the precipitins in the sera of 16 cases of S. viridans endocarditis against the bacterial substances. It is evident that the strongest and most uniform reactions are found in the tests with the 2 protein fractions of S. hetnolyticus, although there are some reactions with the carbohydrate and with the proteins of the other organisms. The weakest reactions occurred in the serum of the only patient in this series in whom clinical history and autopsy findings failed to disclose evidence of rheumatic fever, and in the sera of two patients aged 56 and 69 years.