Validation of an immunodiagnostic assay for detection of 13 Streptococcus pneumoniae serotype-specific polysaccharides in human urine.
To improve the clinical diagnosis of pneumococcal infection in bacteremic and nonbacteremic community-acquired pneumonia (CAP), a Luminex technology-based multiplex urinary antigen detection (UAD) diagnostic assay was developed and validated. The UAD assay can simultaneously detect 13 different serotypes of Streptococcus pneumoniae by capturing serotype-specific S. pneumoniae polysaccharides (PnPSs) secreted in human urine. Assay specificity is achieved by capturing the polysaccharides with serotype-specific monoclonal antibodies (MAbs) on spectrally unique microspheres. Positivity for each serotype was based on positivity cutoff values calculated from a standard curve run on each assay plate together with positive- and negative-control urine samples. The assay is highly specific, since significant signals are detected only when each PnPS was paired with its homologous MAb-coated microspheres. Validation experiments demonstrated excellent accuracy and precision. The UAD assay and corresponding positivity cutoff values were clinically validated by assessing 776 urine specimens obtained from patients with X-ray-confirmed CAP. The UAD assay demonstrated 97% sensitivity and 100% specificity using samples obtained from patients with bacteremic, blood culture-positive CAP. Importantly, the UAD assay identified Streptococcus pneumoniae (13 serotypes) in a proportion of individuals with nonbacteremic CAP, a patient population for which the pneumococcal etiology of CAP was previously difficult to assess. Therefore, the UAD assay provides a specific, noninvasive, sensitive, and reproducible tool to support vaccine efficacy as well as epidemiological evaluation of pneumococcal disease, including CAP, in adults.
Vaccine Research East and Early Development, Pfizer Research, Pearl River, New York, New York, USA. michael.pride@pfizer.com
Michael W
MW
Pride
Susanne M
SM
Huijts
Kangjian
K
Wu
Victor
V
Souza
Sherry
S
Passador
Chunyan
C
Tinder
Esther
E
Song
Arik
A
Elfassy
Lisa
L
McNeil
Ronald
R
Menton
Roger
R
French
Janice
J
Callahan
Chris
C
Webber
William C
WC
Gruber
Marc J M
MJ
Bonten
Kathrin U
KU
Jansen
D000368:Aged; D000818:Animals; D000907:Antibodies, Bacterial; D000911:Antibodies, Monoclonal; D000942:Antigens, Bacterial / Q000032:analysis*; D019411:Clinical Laboratory Techniques / Q000379:methods*; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000379:methods; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008863:Microspheres; D008875:Middle Aged; D011008:Pneumococcal Infections / Q000175:diagnosis*; D011135:Polysaccharides, Bacterial / Q000302:isolation & purification*; D012680:Sensitivity and Specificity; D013296:Streptococcus pneumoniae / Q000737:chemistry*; D014556:Urine / Q000737:chemistry*
D000907:Antibodies, Bacterial; D000911:Antibodies, Monoclonal; D000942:Antigens, Bacterial; D011135:Polysaccharides, Bacterial