Pneumococcal Capsular Polysaccharide in Urine; Detection by Precipitation and Centrifugation

Abstract

Summary and Conclusions The minimal amount of specific soluble substance detectable after its addition to normal urine, and the optimal amount of rabbit antibody required for detection, was investigated for pneumococcal types I, II, III, IV, V, VII, VIII, and XIV. The minimal concentration detectable for I, III, IV, and XIV was 1:200,000 and for II, V, VII, and VIII, 1:400,000. The optimal antibody unitage required varied from 125 to 500 units per cubic centimeter. Concentration of urine containing specific soluble substance yielded roughly equal increases in the concentration of specific soluble substance. The precipitative reaction in urine has been successfully employed to identify the infecting type of pneumococcus in patients whose sputa yielded several types. Pooled rabbit sera, as used in Neufeld typing methods, were successfully employed for the detection of capsular polysaccharide in urine. Centrifugation at 2,000 r.p.m. for 30 minutes, immediately after mixture of urine and antiserum, yielded positive reactions in the full expected range. These reactions are generally more evident than are the reactions obtained after 20 hours by the usual procedure of incubation at 37° for 2 hours and refrigeration overnight. Upon the basis of these experiences we propose the following procedure for the routine detection of urinary polysaccharide, for the 8 types studied (table 5).