Streptococcus pneumoniae (S. pneumoniae) urinary antigen test has been reported to be simple and quick method to perform, and have high sensitivity and specificity. But in clinical examination, because of complicated background, such as pneumonia complicated with other pathogens, clinical usefulness of this test has not been proven yet. The purpose of this study is to clarify its characteristics and usefulness in clinical situation.
S. pneumoniae urinary antigen test was performed to 111 patients suspicious of Community-Acquired Pneumonia (CAP), who had admitted to our hospital. We retrospectively compared clinical characteristics and data between antigen positive and negative group of patients with CAP.
S. pneumoniae urinary antigen tests were positive for 15 patients among 80 ones with CAP (sensitivity 18.8%), and negative for 30 patients among 31 ones without CAP (specificity 96.8%). Positive and negative predictive value rate in diagnosing CAP was 93.8%, and 31.6%. As one of characteristics of positive group in CAP patients, they showed a tendency to be less complicated with other pulmonary diseases than CAP. In CAP patients antibiotics had been given before the test, positive rate was 29.4% (5 of 17 patients), and in CAP ones without antibiotics before the test, positive rate was 15.9% (10 of 63 patients). The blood test showed that the levels of C-reactive protein (CRP) and total protein (TP) were significantly higher and lower respectively in positive group than in negative group (p=0.02, p=0.04). Severity of CAP was significantly higher in positive group than in negative group (p<0.05), but there was no significant difference in mortality between two groups.
S. pneumoniae urinary antigen test is likely to be less influenced by antibiotic treatment and moreover, is suggestive of severity of CAP. This test is very useful both in detecting the pathogen of CAP and in evaluating the severity of CAP.
This test is available not only for establishing the early diagnosis of CAP but also for predicting the prognosis of CAP.
M. Nakayama, None.