244. Development, Qualification, and Clinical Validation of an Immunodiagnostic assay for the Detection of 11 Additional S. pneumoniae Serotype-Specific Polysaccharides in Human Urine

Abstract

BackgroundIdentifying Streptococcus pneumoniae (Sp) serotypes by urinary antigen detection assay (UAD) is the most sensitive and specific way to evaluate the changing epidemiology of non-bacteremic community-acquired pneumonia (CAP) and efficacy of pneumococcal vaccines. We first described an UAD to detect the Sp serotypes 1,-3,-4,-5,-6A,-6B,-7F,-9V,-14,-18C,-19A,-19F,-23F covered by the 13-valent Sp conjugate vaccine PCV13. To assess the pneumococcal disease burden of additional serotypes, a UAD-2 assay was developed to diagnose 11 additional Sp serotypes (-2,-8,-9N,-10A,-11A,-12F,-15B,-17F,-20,-22F,-33F).MethodsUAD-2 specificity was achieved by capturing highly purified pneumococcal polysaccharides with serotype-specific monoclonal antibodies using Luminex technology. Assay qualification assessed accuracy, precision, and sample linearity. Serotype positivity was based on cutoffs determined by non-parametric statistical evaluation of urine samples from individuals without pneumococcal disease. Clinical sensitivity and specificity of the positivity cutoffs were assessed in a clinical validation.ResultsThe UAD-2 was shown to be specific and reproducible. Clinical validation using urine samples from invasive disease patients demonstrated assay sensitivity and specificity of 92.2% and 95.9%, respectively compared with a gold standard of isolating and typing (by Quellung) Sp bacteria from patient samples. Analysis of 11,087 CAP patients showed a UAD-2 and UAD-1 serotype prevalence of 4.33% and 4.60%, respectively (bacteremic and non-bacteremic CAP combined).ConclusionThe qualified/clinically validated UAD-2 method has applicability in understanding the epidemiology of nonbacteremic Sp CAP as well as assessing vaccine efficacy of future pneumococcal conjugate vaccines.Disclosures All authors: No reported disclosures.