Enhancing the etiologic diagnosis of community-acquired pneumonia in adults using the urinary antigen assay (Binax NOW)

SummaryObjectivesApproximately 40% of community-acquired pneumonia (CAP) remains of unknown etiology. To improve the rate of detection of the causative microbiologic agent, the Binax NOW Streptococcus pneumoniae urinary antigen test (UAT) was evaluated.DesignIn this prospective study, 67 adults with CAP were compared with 81 healthy patients to determine sensitivity and specificity of the UAT and its role in improving the etiologic diagnosis of CAP.ResultsAn etiology could be found for 22 patients (33%) using conventional methods (14 S. pneumoniae, sensitivity 64.3%, 1/81 positive UAT control urine samples, specificity 98.8%). This proportion increased to 33 patients (49%) with the addition of the urinary antigen test (p = 0.039). Pneumococcal infection was diagnosed by the UAT in 24% of our patients without an etiologic identification by conventional methods.ConclusionsGiven its excellent specificity, this test can be considered an important tool for detecting S. pneumoniae in CAP of unknown etiology, enabling the diagnosis of pneumococcal pneumonia in a quarter of cases.