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Updated: Apr 5, 2026
Capsular Serotyping of Streptococcus pneumoniae by Latex Agglutination
Published on: September 25, 2014
Development and evaluation of MALDI-TOF MS-based serotyping for Streptococcus pneumoniae
S Nakano1, Y Matsumura2, Y Ito3
1Department of Clinical Laboratory Medicine, Kyoto University Graduate School of Medicine, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto, Japan.
Abstract:
Surveillance of Streptococcus pneumoniae serotypes is important for the successful implementation of vaccination strategies to prevent the spread of invasive pneumococcal diseases. The standard method of serotyping of pneumococcal isolates is the phenotypic Neufeld test, which is cost- and labor-intensive. Recently, matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has been implemented as a rapid, simple and inexpensive method for identifying species. We evaluated the performance of MALDI-TOF MS for serotyping ten major serotypes of S. pneumoniae in Japan (serotypes 3, 6B, 15A, 15C, 19A, 19 F, 23A, 24 F, 35B and 38) using the Biotyper and ClinProTools. After optimizing the settings, we validated their serotyping performance for serotypes 3, 15A and 19A using a separate set of isolates that were not used in the creation of the classification algorithms. A total of 574 isolates of S. pneumoniae collected from Japanese nationwide surveillance studies were included. Of these, 407 isolates belonged to the ten major serotypes. Biotyper and ClinProTools correctly identified 77.9 % and 84.0 %, respectively, of the ten major serotype isolates. The validation analysis included a total of 113 isolates of the serotypes 3, 15A and 19A isolates. Biotyper and ClinProTools correctly identified 85.0 % and 69.9 % of the validation cohort isolates, respectively. MALDI-TOF MS has the potential to discriminate the ten major S. pneumoniae serotypes prevalent in Japan.
Insights
Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) shows promise for rapidly serotyping Streptococcus pneumoniae. This method could improve surveillance and vaccination strategies for invasive pneumococcal diseases.
Area of Science:
- Microbiology
- Mass Spectrometry
- Vaccinology
Background:
- Accurate Streptococcus pneumoniae serotyping is crucial for preventing invasive pneumococcal diseases through vaccination.
- The traditional Neufeld test for pneumococcal serotyping is time-consuming and expensive.
- Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) offers a rapid, cost-effective alternative for species identification.
Purpose of the Study:
- To evaluate the performance of MALDI-TOF MS for serotyping ten major Streptococcus pneumoniae serotypes in Japan.
- To assess the efficacy of Biotyper and ClinProTools software for MALDI-TOF MS-based serotyping.
- To validate the optimized MALDI-TOF MS method for specific serotypes (3, 15A, 19A).
Main Methods:
- MALDI-TOF MS was employed to analyze 574 Streptococcus pneumoniae isolates from Japanese surveillance studies.
- Biotyper and ClinProTools software were utilized for serotype classification.
- Method performance was optimized and validated using distinct isolate sets for serotypes 3, 15A, and 19A.
Main Results:
- Biotyper correctly identified 77.9% of the ten major serotypes, while ClinProTools achieved 84.0%.
- In validation, Biotyper correctly identified 85.0% of serotypes 3, 15A, and 19A isolates.
- ClinProTools achieved 69.9% accuracy in the validation cohort for these specific serotypes.
Conclusions:
- MALDI-TOF MS demonstrates significant potential for discriminating the ten major Streptococcus pneumoniae serotypes prevalent in Japan.
- This technique could enhance the efficiency and cost-effectiveness of pneumococcal serotype surveillance.
- Further optimization may improve the accuracy of MALDI-TOF MS for broader pneumococcal serotyping applications.
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