Abstract
Although pneumococci can be typed directly from sputum, it has been recognized that the results are sometimes unsatisfactory. Taplin, Meneely and Hettig 1 have outlined an improved method using fresh sputum to obtain the Quellung phenomenon. Essentially, this method consists of breaking up and suspending the sample in saline, centrifuging, and using the sediment for typing. The authors suggested that the water-soluble capsular polysaccharide might well be the interfering substance, which was removed by their technic.
In work published elsewhere, 2 it has been determined that in undiluted samples of ground lung from pneumonic rats, pneumococci present did not give the Quellung reaction with specific antiserum. The reaction did occur if the material were sufficiently diluted with PSS. Heidelberger 3 has shown that excess of antigen prevents visible evidence of antigen-antibody reaction, and has ably discussed the reversibility of the precipitin and agglutinin reactions. Since the above findings indicated that excess antigen prevented the occurrence of the Quellung reaction, it seemed that reversibility of this phenomenon might likewise take place. Hence, the following experiments were performed.
In each of 4 serological tubes were placed 0.1 cc of a broth culture of Type I pneumococcus and 0.1 cc of undiluted type-specific rabbit antiserum; after a short interval, the pneumococci were examined for the presence of swollen capsules. These were uniformly present. Then 0.1 cc of dilutions of Type I polysaccharides were added to each tube to give final amounts of 1.0 mg, 0.1 mg, 0.01 mg, and 0.001 mg in 0.3 cc of fluid, respectively. Five minutes later, the preparations were reëxamined. In the first 2 tubes, the swollen capsules had disappeared. In the last 2 tubes, no change was observed.
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