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An emm-type specific qPCR to track bacterial load during experimental human Streptococcus pyogenes pharyngitis
Loraine V Fabri1,2, Kristy I Azzopardi1, Joshua Osowicki3,4,5
1Tropical Diseases Research Group, Murdoch Children's Research Institute, Melbourne, Victoria, Australia.
BMC Infectious Diseases
|May 22, 2021
Summary
A new molecular method accurately quantifies Streptococcus pyogenes bacterial load in throat swabs. This supports vaccine development by enabling reliable measurement in a controlled human infection model.
Area of Science:
- Microbiology
- Molecular Diagnostics
- Vaccinology
Background:
- Streptococcus pyogenes poses a significant global health burden.
- Developing vaccines for S. pyogenes is crucial.
- A controlled human infection model is essential for accelerating vaccine development.
Purpose of the Study:
- To develop a precise molecular method for quantifying S. pyogenes bacterial load.
- To validate this method using pharyngeal swabs from a human challenge study.
- To support the advancement of S. pyogenes vaccine candidates.
Main Methods:
- Combined sequential RNA + DNA extraction was compared to separate extractions.
- An emm-type specific quantitative PCR (qPCR) was designed for the emm75 strain.
- qPCR results were validated against traditional culture methods.
Main Results:
- The qPCR demonstrated 100% specificity for the emm75 strain against other pathogens.
- Combined extraction yielded comparable results to separate methods.
- The molecular method achieved 98.8% sensitivity compared to culture.
Conclusions:
- A reliable molecular assay for S. pyogenes quantification in throat swabs was successfully developed.
- This method is suitable for use in controlled human infection models.
- The findings facilitate improved S. pyogenes vaccine research.
