Utility of a Sputum Antigen Detection Test in Pneumococcal Pneumonia and Lower Respiratory Infectious Disease in Adults.

To compare the utility of Gram staining, a urinary antigen detection kit and a sputumantigen detection kit were examined for the rapid and early detection of pneumococcal pneumoniaand lower respiratory infectious diseases.A newly developed sputumpneumococcal antigen detection kit (RAPIRUN), Gram staining, and urinary antigen detection kit (BinaxNOW) were comparatively evaluated for their ability to detect Streptococcus pneumoniae in patients with pneumonia or lower respiratory tract infection. Sputum cultureresults were used as a standard for comparison. Furthermore, the pneumococcus-positive rates in culture and rapid tests were compared using polymerase chain reaction (PCR) as a reference.Of the 169 patients studied, 54 (32.0%) tested positive for S. pneumoniae in culture. S. pneumoniae detection sensitivities for Gram staining, RAPIRUN, and BinaxNOW were 75.9%, 90.7%, and 53.7%, respectively; thus, RAPIRUN had a significantly higher sensitivity than BinaxNOW (p<0.001). For patients with ≥10(5) copies/μg of pneumococcal surface protein A DNA PCR analysis, the detection rates of culture, Gram staining, and RAPIRUN were 85.2%, 72.1%, and 82.0%, respectively, however, the detection rate of BinaxNOW was only 47.5%. Comparisons among 45 patients with culture-positive pneumococcal pneumoniarevealed that RAPIRUN had a significantly higher detection rate than BinaxNOW in the mild cases (p<0.006), regardless of the number of days from onset (p<0.03).RAPIRUN is a rapid testing kit that detects S. pneumoniae in sputumwith a high sensitivity and specificity. It is a particularly more useful detection kit than BinaxNOW for early and mild community-acquired pneumoniain pre-treatment patients whose sputumspecimens can be obtained.