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Updated: May 29, 2026
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Constructing Mutants in Serotype 1 Streptococcus pneumoniae strain 519/43
Published on: September 11, 2020
Population structure of hyperinvasive serotype 12F, clonal complex 218 Streptococcus pneumoniae revealed by
Alexey V Rakov1, Kimiko Ubukata, D Ashley Robinson
1Department of Microbiology, University of Mississippi Medical Center, Jackson, MS, United States.
Summary
Multilocus boxB sequence typing (MLBT) enhanced Streptococcus pneumoniae serotype 12F outbreak investigations. This method revealed hidden population structures and genetic diversity in hyperinvasive pneumococci.
Area of Science:
- Microbiology and Infectious Diseases
- Population Genetics
- Molecular Epidemiology
Background:
- Recurrent outbreaks of invasive disease caused by Streptococcus pneumoniae serotype 12F, clonal complex 218, have occurred in the United States.
- Conventional multilocus sequence typing (MLST) has limited resolution for distinguishing between outbreaks of this pathogen.
- Understanding the population structure of hyperinvasive pneumococci is crucial for effective surveillance and control.
Purpose of the Study:
- To develop and evaluate a novel typing method with improved resolution for Streptococcus pneumoniae serotype 12F.
- To investigate the population structure, genetic diversity, and evolutionary dynamics of clonal complex 218.
- To assess the utility of the new typing method in distinguishing between outbreaks and for surveillance purposes.
Main Methods:
- A total of 203 outbreak and surveillance isolates of Streptococcus pneumoniae serotype 12F, collected over 22 years from 34 US states and eight countries, were analyzed.
- Conventional multilocus sequence typing (MLST) was performed.
- A novel multilocus boxB sequence typing (MLBT) method was developed, targeting 10 variable boxB minisatellite loci, to enhance typing resolution.
Main Results:
- Conventional MLST identified only five types and could not distinguish between most of the four major outbreaks.
- MLBT successfully identified 86 distinct types and differentiated between each of the four outbreaks.
- MLBT revealed two major clusters, geographically (western vs. easterly US) and temporally (pre- vs. post-vaccine licensure) differentiated, with distinct population dynamics.
Conclusions:
- Multilocus boxB sequence typing (MLBT) provides significantly higher resolution than conventional MLST for characterizing Streptococcus pneumoniae serotype 12F.
- MLBT uncovered hidden aspects of the population structure and genetic diversity within this hyperinvasive clonal complex.
- MLBT is a valuable adjunct tool for outbreak investigations, surveillance, and population genetics studies of other pneumococcal clonal complexes.
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