Assessment of a urinary antigen test in inpatients with pneumococcal pneumonia

Streptococcus pneumonia is one of the most important pathogens in community- acquired pneumonia. Diagnosis of this disease by conventional methods is often problematic. Therefore, a sensitive and specific diagnostic method can be helpful. The aim of this study was to evaluate the sensitivity and specificity of a rapid urinary antigen detection test in patients with pneumonia. In a cross-sectional study, a total number of 66 patients including 47 (71.2%) males and 19 (28.8%) females over 18 years old were divided into two group. The case group included 33 patients with pneumococcal pneumonia while the control group consisted of 33 patients with non-pneumococcal pneumonia. We compared the sensitivity and specificity of an in-vitro rapid immunochromatography (IC) pneumococcal urinary antigen test between the two groups. While 23 patients (69.7%) in the case group had positive urine antigen test results, no control patient with positive urine antigen test result was detected. The sensitivity of urinary antigen test in the case group was 69.70% (95% CI: 51.29-84.38). The specificity of the test was determined as 100% (95% CI: 89.32-100). Positive and negative predictive values of the test were 100% (85.05-100) and 76.74% (61.36-88.23), respectively. Pneumococcal urinary antigen IC test is a sensitive and highly specific method for diagnosis of pneumococcal pneumonia.