Development of an Extended-Specificity Multiplex Immunoassay for Detection of Streptococcus pneumoniae Serotype-Specific Antigen in Urine by Use of Human Monoclonal Antibodies

Abstract

Current pneumococcal vaccines cover the 10 to 23 most common serotypes of the 92 presently described. However, with the increased usage of pneumococcal-serotype-based vaccines, the risk of serotype replacement and an increase in disease caused by nonvaccine serotypes remains. Serotype surveillance of pneumococcal infections relies heavily on culture techniques, which are known to be insensitive, particularly in cases of noninvasive disease. Pneumococcal-serotypespecific urine assays offer an alternative method of serotyping for both invasive and noninvasive disease. However, the assays described previously cover mainly conjugate vaccine serotypes, give little information about circulating nonvaccine serotypes, and are currently available only in one or two specialist laboratories. Our laboratory has developed a Luminex-based extended-range antigen capture assay to detect pneumococcal-serotype-specific antigens in urine samples. The assay targets 24 distinct serotypes/serogroups plus the cell wall polysaccharide (CWP) and some cross-reactive serotypes. We report that the assay is capable of detecting all the targeted serotypes and the CWP at 0.1 ng/ml, while some serotypes are detected at concentrations as low as 0.3 pg/ml. The analytical serotype specificity was determined to be 98.4% using a panel of polysaccharide-negative urine specimens spiked with nonpneumococcal bacterial antigens. We also report clinical sensitivities of 96.2% and specificities of 89.9% established using a panel of urine specimens from patients diagnosed with community-acquired pneumonia or pneumococcal disease. This assay can be extended for testing other clinical samples and has the potential to greatly improve serotype-specific surveillance in the many cases of pneumococcal disease in which a culture is never obtained.KEYWORDS diagnostics, immunization, monoclonal antibodies, pneumococcus, surveillance studies D espite being vaccine preventable, Streptococcus pneumoniae (pneumococcus) remains a major cause of morbidity and mortality worldwide. Pneumococcal disease (PD) includes both invasive and noninvasive disease. The former includes bacteremia and meningitis; the latter, nonbacteremic pneumonia, sinusitis, and acute otitis media. To date, 97 "serotypes" of pneumococcus have been reported (1); however, some of these show only genotypic differences and produce the same polysaccharide structures (2). Ninety-two serotypes are currently described by the Danish system using commercial typing sera from SSI Diagnostica AG (Hillerød, Denmark). These serotypes differ in

Effectiveness of the 23-valent pneumococcal polysaccharide vaccine against vaccine serotype pneumococcal pneumonia in adults: A case-control test-negative design study

“…These pathogens commonly colonise the nasopharynx and mouth although they are not normally associated with a clinical diagnosis of CAP. The Bio-plex24 assay is highly sensitive [ 15 ]. It is therefore possible that there is a nonpneumococcal provenance for the detected serotype 5 antigen in our cases.…”

“…For this analysis, only patients providing a sample subjected to pneumococcal serotype-specific testing were included. Pneumococcal serotype was identified using the following: (i) for bacteraemic cases: slide agglutination tests with latex antisera (ImmuLex Pneumotest kit, SSI Diagnostica, Hillerød, Denmark) or standard factor sera (SSI Diagnostica), or (from October 2017) whole genome sequencing; (ii) for NIPP cases: multiplex immunoassay (Bio-plex24) applied to urine samples to detect pneumococcal serotypes 1, 2, 3, 4, 5, 6A, 6B, 7F, 8, 9N, 9V, 10A, 11A, 12F, 14, 15B, 17F, 18C, 19A, 19F, 20, 22F, 23F, 33F and the pneumococcal cell-wall polysaccharide plus some cross-reactive serotypes [ 6 , 15 , 16 ].…”

Pneumococcal serotype trends, surveillance and risk factors in UK adult pneumonia, 2013–18

“…Since 2008, we have conducted a prospective population-based adult pneumococcal pneumonia study to determine changes in clinical disease and the responsible pneumococcal serotypes 7 11. Recently, a novel, validated 24-valent multiplex urinary immunoassay was developed to detect PCV and PPV serotypes in patients with non-invasive disease 12. We report the use of this assay in a previously unreported cohort of patients to describe a) serotype trends in adult pneumococcal pneumonia since PCV13 replaced PCV7 and b) the clinical risk groups associated with vaccine-type disease.…”

Invasive Pneumococcal Disease in UK Children <1 Year of Age in the Post–13-Valent Pneumococcal Conjugate Vaccine Era: What Are the Risks Now?

“…Streptococcus pneumoniae is a major cause of meningitis, septicaemia and pneumonia worldwide and is associated with significant morbidity and mortality, especially in young children, the elderly and those with underlying health conditions [1][2][3]. There are currently 92 distinct pneumococcal serotypes based on polysaccharide capsular differences [4][5][6]. Pneumococcal conjugate vaccines (PCVs) have been part of the UK infant immunisation programme since 2006, initially using a vaccine covering the 7 most prevalent pneumococcal serotypes causing invasive pneumococcal disease (IPD) in children (PCV7, Prevenar®, Pfizer, New York).…”