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Capsular Serotyping of Streptococcus pneumoniae Using the Quellung Reaction
Published on: February 24, 2014
From Quellung to multiplex PCR, and back when needed, in pneumococcal serotyping
Lotta Siira1, Tarja Kaijalainen, Lotte Lambertsen
1Department of Infectious Disease Surveillance and Control, National Institute for Health and Welfare, Helsinki, Finland. lotta.siira@thl.fi.
Journal of Clinical Microbiology
|June 14, 2012
Summary
A new PCR-based method accurately identifies Streptococcus pneumoniae serotypes, improving surveillance and vaccine monitoring. This validated protocol enhances efficiency and reduces costs for invasive pneumococcal disease tracking.
Area of Science:
- Microbiology
- Molecular Biology
- Epidemiology
Background:
- Streptococcus pneumoniae serotyping is crucial for vaccine development and disease surveillance due to over 90 distinct serotypes.
- Current serotyping methods require continuous monitoring for efficacy and accurate identification of circulating strains.
Purpose of the Study:
- To modify and validate a Polymerase Chain Reaction (PCR)-based scheme for rapid and accurate serotyping of invasive pneumococci.
- To implement an efficient, cost-effective method for serotype-specific surveillance of pneumococcal isolates in Finland.
Main Methods:
- Development and validation of a multiplex PCR (mPCR) protocol using six sequential reactions.
- Comparison of PCR-based serotyping results with traditional Quellung testing for 170 invasive pneumococcal isolates.
- Application of the validated mPCR scheme for routine surveillance of over 1,500 invasive pneumococcal isolates.
Main Results:
- The PCR-based scheme achieved 98.8% accuracy in serotype deduction compared to traditional methods.
- The mPCR protocol demonstrated a success rate of over 99% for processed isolates.
- Identified discrepancies, such as serotype 19F PCR-positive isolates being serotype 19A by Quellung, prompting protocol refinement.
Conclusions:
- The validated PCR-based scheme provides a precise, effective, and cost-efficient method for Streptococcus pneumoniae serotyping.
- Routine implementation of the mPCR protocol enhances surveillance capabilities for invasive pneumococcal disease.
- Ongoing vigilance and integration with phenotypic methods like Quellung testing are essential to prevent underreporting of key serotypes, such as 19A.
