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Updated: Nov 17, 2025
Capsular Serotyping of Streptococcus pneumoniae by Latex Agglutination
Published on: September 25, 2014
23-valent polysaccharide vaccine (PPSV23)-targeted serotype-specific identification of Streptococcus pneumoniae using
Jiwon Lee1,2,3, Youngbae Yoon1,2,3, Eun Jin Kim1,2,3
1Division of Pediatric Dentistry, Department of Human Development and Fostering, Meikai University School of Dentistry, Saitama, Japan.
Abstract:
Reports of invasive disease due to Streptococcus pneumoniae have declined since the introduction of pneumococcal conjugate vaccines (PCV7 and PCV13). The incidence of invasive diseases due to S. pneumoniae that are not addressed by the vaccines, however, has increased in children and adults, creating a global public health problem. Previously, we established the loop-mediated isothermal amplification (LAMP) method for a PCV13 serotype-specific assay. In the current study, we developed a rapid, simple, and cost-effective assay to detect serotypes in the 23-valent pneumococcal polysaccharide vaccine (PPSV23) using the LAMP method. In this study, LAMP primer sets for serotypes 2, 8, 9N, 10A, 11A, 12F, 15B, 17F, 20, 22F, and 33F of S. pneumoniae were developed. The reactivity, specificity, and sensitivity of LAMP assays were determined and compared to those of conventional PCR. The feasibility of LAMP assays in clinical application in patients with invasive pneumococcal diseases was validated by defining the detection limit of the LAMP assay with bacterial genomic DNA-spiked blood specimens. The specificity of each LAMP assay was determined using 44 serotypes of pneumococcal strains. Their sensitivity was 100 copies per reaction versus 103 to 106 copies per reaction for PCR assays. Using DNA-spiked blood specimens, excluding the LAMP assay that targeted serotype 22F (103 copies per reaction), the limit of detection of the LAMP assay was similar to that with purified DNA as the template (102 copies per reaction), compared with 103 to >106 copies per reaction for PCR assays. In conclusion, a rapid and simple LAMP-based PPSV23-targeted serotype detection assay was developed for use in many countries. This study is the first report of a LAMP-based assay for identification of PPSV23 serotypes. Further evaluation of this assay is needed through surveillance and vaccine efficacy studies.
Insights
A new loop-mediated isothermal amplification (LAMP) assay rapidly detects Streptococcus pneumoniae serotypes targeted by PPSV23 vaccine. This method offers a simple, cost-effective tool for identifying pneumococcal serotypes not covered by other vaccines.
Area of Science:
- Microbiology
- Vaccinology
- Molecular Diagnostics
Background:
- Invasive pneumococcal disease (IPD) incidence has declined with pneumococcal conjugate vaccines (PCV7, PCV13).
- However, non-vaccine serotypes of Streptococcus pneumoniae are increasing, posing a global health challenge.
- Previous work established a LAMP assay for PCV13 serotypes.
Purpose of the Study:
- To develop a rapid, simple, and cost-effective loop-mediated isothermal amplification (LAMP) assay for detecting serotypes covered by the 23-valent pneumococcal polysaccharide vaccine (PPSV23).
- To validate the clinical feasibility of the developed LAMP assay for identifying S. pneumoniae serotypes in invasive pneumococcal disease cases.
Main Methods:
- Development of LAMP primer sets for 11 specific S. pneumoniae serotypes included in PPSV23.
- Determination of LAMP assay reactivity, specificity, and sensitivity, comparing results with conventional PCR.
- Validation of clinical feasibility using bacterial genomic DNA-spiked blood specimens to establish the limit of detection.
Main Results:
- Successfully developed LAMP primer sets for 11 PPSV23 serotypes.
- The LAMP assay demonstrated high sensitivity (100 copies/reaction) and specificity against 44 pneumococcal serotypes.
- Detection limits in spiked blood specimens were comparable to purified DNA, significantly lower than PCR methods.
Conclusions:
- A rapid, simple, and cost-effective LAMP-based assay for detecting PPSV23-targeted pneumococcal serotypes has been successfully developed.
- This represents the first report of a LAMP assay for identifying PPSV23 serotypes.
- Further evaluation through surveillance and vaccine efficacy studies is recommended.
