A Combined Aptamer Pulldown-DNAzyme Cleavage Assay for Intact Methicillin Resistant Staphylococcus aureus Cells

Area of Science:

• Biotechnology
• Molecular Biology
• Analytical Chemistry

Background:

• Accurate detection of methicillin-resistant Staphylococcus aureus (MRSA) is crucial for effective antibiotic treatment.
• Current MRSA detection methods can be time-consuming and require complex sample preparation.
• There is a need for rapid, convenient, and selective diagnostic tools for MRSA.

Purpose of the Study:

• To develop a novel biosensor for the selective preconcentration and detection of MRSA.
• To combine a DNA aptamer and an RNA-cleaving DNAzyme (RCD) for dual-marker detection.
• To achieve rapid and sensitive MRSA detection in complex biological samples.

Main Methods:

• Generation of a DNA aptamer targeting penicillin-binding protein 2a (PBP2a) and immobilization on agarose beads for MRSA capture.
• Utilizing a previously reported RCD for Staphylococcus aureus (SA) to detect a second protein marker after cell lysis.
• Integration of aptamer-based capture with RCD detection via fluorescence and lateral flow assays (LFD).

Main Results:

• The combined aptamer-RCD system demonstrated selective preconcentration and detection of MRSA.
• An optimized LFD assay achieved a detection limit of approximately 10^3 colony-forming units (cfu) per mL for MRSA.
• The assay successfully detected MRSA in complex matrices like nasal mucus and serum within 1 hour.

Conclusions:

• This study presents the first aptamer-RCD combination for selective MRSA detection.
• The developed method offers a rapid, convenient, and sensitive approach for MRSA diagnostics.
• The assay shows potential for clinical applications with minimal sample processing.