Current methods for capsular typing of Streptococcus pneumoniae

Area of Science:

• Microbiology
• Vaccinology
• Genomics

Background:

• Streptococcus pneumoniae causes significant respiratory illness, particularly in young children and the elderly.
• Current pneumococcal conjugate vaccines (PCV) cover a limited number of the 98 known serotypes, necessitating surveillance for non-vaccine serotypes.
• Post-PCV implementation requires rapid, accurate, and cost-effective methods for pneumococcal serotyping.

Purpose of the Study:

• To review and describe serotyping methods for Streptococcus pneumoniae published before November 10, 2014.
• To evaluate available methods for pneumococcal capsule typing in the context of post-vaccine surveillance.
• To inform the selection of appropriate typing methods for monitoring vaccine impact and future vaccine design.

Main Methods:

• A systematic review of published pneumococcal capsule typing methods.
• Categorization of identified methods into serological, semi-automated molecular, and whole-genome sequencing approaches.
• Analysis of 16 distinct typing methods, including the gold-standard Quellung reaction.

Main Results:

• Six serological, eight semi-automated molecular, and one whole-genome sequencing method were identified.
• No single method is universally optimal for all pneumococcal typing applications.
• The Quellung reaction remains the gold-standard, but resource and sample considerations are vital for method selection.

Conclusions:

• Selecting the most appropriate pneumococcal typing method depends on laboratory resources, sample type, and desired turnaround time.
• A combination of phenotypic and genotypic methods is likely optimal for monitoring PCV impact and informing future vaccine formulations.
• Continued surveillance and development of effective typing strategies are essential for controlling pneumococcal disease.