Comparative evaluation of the novel IMMUNOCATCHTM Streptococcus pneumoniae (EIKEN CHEMICAL CO., LTD) test with the Uni-GoldTM Streptococcus pneumoniae assay and the BinaxNOW® Streptococcus pneumoniae antigen card for the detection of pneumococcal capsular antigen in urine samples.

Abstract

Community-acquired pneumonia (CAP) is one of the major causes of morbidity, mortality and hospitalization, and S. pneumoniae is the most frequently isolated etiologic agent. The pneumococcal urinary antigen test (PUAT) is among the recommended methods to identify the causative agent in CAP patients. A novel PUAT (IMMUNOCATCHTMStreptococcus pneumoniae) was compared with the Uni-GoldTMS. pneumoniae assay routinely used in our laboratory and with the widely used BinaxNOW® S. pneumoniae antigen card. A total of 218 (183 freshly harvested and 35 frozen) urine samples (US) submitted for the detection of pneumococcal urinary antigen (PUAT) between December 2016 and November 2018 were evaluated. A number of 160 negative and 41 positive concordant results were scored for all the three assays. A total of 17 US gave discrepant results. The sensitivity and specificity of Immunocatch compared with Uni-Gold were 73.2% and 98.8%, respectively, and compared with BinaxNOW were 97.6% and 98.8%, respectively. The overall percent agreement (OPA) and the Cohen's kappa coefficient between the Immunocatch and the Uni-Gold resulted 92.2% and 0.78%, respectively, and compared with BinaxNOW were 98.6% and 0.95%, respectively. These performances suggest that the novel Immunocatch S. pneumoniae test is a useful tool for qualitative detection of S. pneumoniae capsular antigen in US.