Rapid visualization and detection of Staphylococcus aureus based on loop-mediated isothermal amplification.

Area of Science:

• Microbiology
• Molecular Biology
• Diagnostic Assays

Background:

• Staphylococcus aureus is a significant clinical pathogen causing various infections.
• Rapid and reliable detection assays for S. aureus are crucial for timely diagnosis and treatment.
• Existing diagnostic methods may lack the speed or sensitivity required for early detection.

Purpose of the Study:

• To develop a closed-tube, visual, colorimetric loop-mediated isothermal amplification (LAMP) assay for detecting Staphylococcus aureus.
• To optimize the LAMP reaction conditions for enhanced specificity and sensitivity.
• To evaluate the diagnostic accuracy of the developed LAMP assay compared to conventional methods using clinical isolates.

Main Methods:

• Development of a closed-tube loop-mediated isothermal amplification (LAMP) assay.
• Utilized hydroxy naphthol blue (HNB) as a colorimetric indicator for visual detection.
• Optimized reaction parameters including temperature, Mg2+, dNTP, HNB concentrations, and incubation time.
• Validated specificity against 14 non-S. aureus strains and determined the limit of detection (LOD).
• Evaluated diagnostic efficacy using 220 S. aureus and 149 non-S. aureus clinical isolates.

Main Results:

• The optimized LAMP assay demonstrated 100% specificity for S. aureus with no cross-reactivity.
• The limit of detection (LOD) was as low as 8 copies/reaction for plasmid DNA or 400 CFU/reaction for S. aureus.
• LAMP achieved a tenfold lower LOD compared to conventional PCR.
• The assay showed a high diagnostic accuracy of 99.46% on clinical isolates.

Conclusions:

• The developed colorimetric LAMP assay is a highly specific and sensitive method for detecting Staphylococcus aureus.
• This assay offers a reliable and rapid alternative for the diagnosis of S. aureus infections.
• LAMP presents a promising tool for clinical settings requiring swift and accurate pathogen identification.