Avicenna J Med Biotech arij002 Avicenna Journal of Medical Biotechnology 2008-2835 2008-4625 Avicenna Research Institute ajmb60491 Fluorescent Detection of Methicillin Resistant Staphylococcus aureus by Loop-mediated Isothermal Amplification Assisted with Streptavidin-coated Quantum Dots AliasgharianAilyGillPooriaAhanjanMohammadRafatiAdele 14 1 79 88 28 6 2021 18 10 2021

<p><span style="font-size:11pt">Background:<span style="font-size:11.5pt"> Methicillin Resistance<em> Staphylococcus aureus</em> (<em>MRSA</em>) could be considered as a major concern in medicine can cause nosocomial infection and bacteremia, especially in patients using catheter and household medical devices. </span></span></p> <p><span style="font-size:11pt">Methods: <span style="font-size:11.5pt">Using molecular diagnostic methods are important for identification of<em> MRSA </em>from the Methicillin Sensitive<em> Staphylococcus aureus</em> (<em>MSSA</em>). Here we described a fluorescent assay using biotin-labelling Loop-mediated isothermal amplification (LAMP) method assisted with streptavidin-coated Quantum Dots (QDs) for detection of <em>MRSA</em>. For comparison, another fluorescent assay using LAMP assisted with Green Viewer (GV; a fluorescent dye) was applied for detection of <em>MRSA</em>. The <em>mecA</em> gene was selected as the target for amplification by LAMP and for biotin-labeling of the LAMP amplicons, biotin-11-dUTP was mixed with the dNTPs (deoxy Nucleotide Phosphates) in LAMP reaction. For determining the clinical performance of the developed assay, 30 blood samples with <em>MRSA</em> positive results were tested with QD-LAMP</span><span style="font-size:11.5pt">, the conventional LAMP, GV-LAMP, and </span><span style="font-size:11.5pt">Polymerase Chain Reaction</span><span style="font-size:11.5pt"> (PCR). </span></span></p> <p><span style="font-size:11pt">Results: <span style="font-size:11.5pt">Obtained results indicated that % sensitivity of QD-LAMP was 86.66% for detection of <em>mecA</em> positive <em>MRSA</em> samples; however, the Limit of Detection (LoD) of QD-LAMP was </span><span style="font-size:11.5pt">1.5&times;10<sup>4</sup></span> <span style="font-size:11.5pt">Colony Forming Unit</span><span style="font-size:11.5pt"> (CFU). </span></span></p> <p><span style="font-size:11pt">Conclusion: <span style="font-size:11.5pt">The results suggested that </span><span style="font-size:11.5pt">the QD-LAMP </span><span style="font-size:11.5pt">assay was easy to operate and could be used for detection of <em>MRSA</em> in parallel to the blood culture with less sensitivity for detection of bacteremia and pediatric septicemia with low counts of <em>MRSA</em>.</span></span></p>