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The objectives of this study were to investigate the usefulness of the urinary antigen detection kit for Streptococcus pneumoniae and to analyze the duration of urinary antigen presence in pneumococcal pneumonia. We evaluated this kit in 51 patients whose symptoms and laboratory data suggested pneumococcal pneumonia and who were admitted to Toho University Hospital (Tokyo, Japan) between July 2000 and June 2001. S. pneumoniae urinary antigen was detected in 21 of 51 patients. These 21 patients were further investigated with their clinical characteristics and the duration of a positive urinary antigen reaction. S. pneumoniae was isolated by sputum or blood culture in 10 cases (47.6%), whereas 11 cases (52.4%) showed positive results only with urinary antigen but not in cultures. When the urinary antigen kits were tested, 19 cases (90.5%) were treated with antibiotics. Eleven of the 21 patients were continuously tested with this kit. The mean duration for which these patients were urinary antigen-positive was 7.3 weeks. Patients whose pneumonia was severe or who had positive culture results tended to be positive for urinary antigen for a prolonged period. This kit has high sensitivity and specificity, is suitable for rapid diagnosis and is effective after antibiotic therapy. However, because the positive test kit results are prolonged after recovery from pneumonia in some cases, this kit is not suitable for the evaluation of therapeutic effect.

We evaluated a new rapid urinary antigen detection kit. NOW Streptococcus pneumoniae (Binax Inc., USA) that detected S. pneumoniae antigen by immunochromatographic membrane assay, with 66 Japanese adult patients of community acquired pneumonia. Twenty-two (33.3%) patients were found to be positive with the kit and S. pneumoniae was isolated from six patients (27.3%) of these 22 patients. S. pneumoniae was not isolated from eight of the 22 patients by blood or sputum culture. Analysis of clinical laboratory data showed that the levels of C-reactive protein (CRP) in the serum were significantly higher in the urine-antigen positive group than those in the urine-antigen negative group. There were no significant difference between the two groups including renal function, urinalysis, clinical symptom, and severity of pneumonia. Our study suggests that more cases of community acquired pneumonia are caused by S. pneumoniae than conventional tests can currently confirm. Since it is not technically complex, does not require equipment, and detects within as quickly as in 15 minutes, the S. pneumoniae urinary antigen kit is useful for rapid diagnosis of community acquired pneumonia in adults.