Development of propidium monoazide-recombinase polymerase amplification (PMA-RPA) assay for rapid detection of...

Area of Science:

• Microbiology
• Molecular Biology
• Diagnostic Assays

Background:

• Streptococcus pyogenes (Group A Streptococcus, GAS) and Streptococcus agalactiae (Group B Streptococcus, GBS) are significant public health pathogens.
• Rapid and accurate detection methods are crucial for timely diagnosis and treatment.

Purpose of the Study:

• To develop a rapid, sensitive, and specific molecular assay for the simultaneous detection of GAS and GBS.
• To evaluate the performance of the assay in clinical samples and assess its ability to differentiate between live and dead bacteria.

Main Methods:

• Development of a double recombinase polymerase (RPA) amplification assay targeting specific genes (speB for GAS, SIP for GBS).
• Specificity testing using known strains.
• Validation using clinical samples and comparison with traditional biochemical methods.
• Determination of the limit of detection (LOD) and testing with simulated contaminated samples.
• Evaluation of propidium monoazide (PMA) treatment to exclude DNA from dead cells.

Main Results:

• The double RPA assay demonstrated high specificity for GAS and GBS.
• Performance in clinical samples was comparable to traditional methods.
• The LOD was determined to be ≤100 copies per reaction.
• Simulated samples with 10^3 CFU/mL of GAS and GBS were detected within 4 hours.
• Results were obtainable within 20 minutes at 37°C.
• PMA treatment effectively eliminated fluorescence signals from DNA of dead cells.

Conclusions:

• The developed double RPA assay provides a rapid and sensitive method for detecting GAS and GBS.
• The integration of PMA (PMA-RPA) allows for the detection of viable bacteria, crucial for accurate diagnosis.
• This technology holds promise for field applications and rapid point-of-care diagnostics.