Multiple-locus variable-number tandem-repeat analysis of Streptococcus pneumoniae and comparison with multiple loci...

Area of Science:

• Microbiology
• Genetics
• Epidemiology

Background:

• Streptococcus pneumoniae causes significant global morbidity and mortality.
• Pneumococcal diversity is characterized by over 93 serotypes, influencing virulence.
• Molecular genotyping, including Pulsed-Field Gel Electrophoresis (PFGE) and Multiple Loci Sequence Typing (MLST), tracks pathogen spread and resistance.

Purpose of the Study:

• To confirm the utility of Multiple-Locus Variable-Number Tandem-Repeat Analysis (MLVA) for Streptococcus pneumoniae genotyping.
• To compare the discriminatory power of MLVA against MLST for differentiating strains within the same Sequence Type (ST).
• To define a minimal, universal set of MLVA markers with discriminatory power comparable to MLST.

Main Methods:

• Genotyping of 331 Streptococcus pneumoniae isolates from the UK using established MLVA marker sets.
• Comparative analysis of MLVA and MLST results, including Minimum Spanning Tree construction.
• Selection of optimal MLVA markers based on Diversity Index (>0.8) and population-specific needs.

Main Results:

• 220 MLVA types were identified within 10 Sequence Types (STs).
• MLVA successfully resolved ST162 into two distinct clonal complexes.
• A minimal set of 7 MLVA markers, including two universal markers, demonstrated strain clustering similar to MLST.

Conclusions:

• MLVA can effectively discriminate relevant subgroups within the same ST of Streptococcus pneumoniae.
• MLVA typing allows for the inference of Sequence Type (ST) from MLVA Type.
• MLVA is a valuable tool for investigating local outbreaks and monitoring global clone dissemination and variant emergence.