Comparison of Four Streptococcus pneumoniae Urinary Antigen Tests Using Automated Readers

Streptococcus pneumoniae urinary antigen tests (UATs) may be interpreted using automatic readers to potentially automate sample incubation and provide standardized results reading. Here, we evaluated four UATs the BinaxNOW S. pneumoniae Antigen Card (Abbott, Chicago, IL, USA), ImmuView S. pneumoniae and Legionella (SSI Diagnostica, Hillerød, Denmark), STANDARD F S. pneumoniae Ag FIA (SD Biosensor, Gyeonggi, South Korea), and Sofia S. pneumoniae FIA (Quidel Corporation, San Diego, CA, USA) with their respective benchtop readers for their ability to detect S. pneumoniae urinary antigen. We found that these assays had a sensitivity of 76.9-86.5%, and specificity of 84.2-89.7%, with no significant difference found among the four UATs. The assays had a high level of agreement with each other, with 84.5% of samples testing consistently across all four assays. The automatically and visually read test results from the two immunochromatographic assays, BinaxNOW and ImmuView, were compared and showed excellent agreement between the two types of reading. Immunofluorescent-based assays, Sofia and STANDARD F, had significantly less time to detect compared to the two immunochromatographic assays due to having less assay setup procedures and shorter sample incubation times. In conclusion, the four UATs performed similarly in the detection of S. pneumoniae urinary antigen, and readers can bring increased flexibility to running UATs in the clinical routine.