Design of melting curve analysis (MCA) by real-time polymerase chain reaction assay for rapid distinction of staphylococci and antibiotic resistance

Abstract

Background: Staphylococci are important pathogenic bacteria responsible for a range of diseases in humans. Hence, detection of Staphylococcus aureus from coagulase-negative staphylococci (CoNS) is essential in various infections. Objectives: The aim of this study was to design a melting curve analysis (MCA) assay based on Multiplex Real-Time PCR for rapid detection of staphylococci and antibiotic resistance. Methods: The current study used standard strains of positive and negative coagulase staphylococci. As the first step, serial dilutions were prepared with ratios of 108 to 101 cfu/mL based on standard bacterial concentration with 0.5 McFarland and the results were illustrated in dedicated melting curves. Results: All melting curves of gene amplification had an equal melting point. In all dilutions, the observed melting temperatures shown in the melting curves of gene amplification were equal to 83.79°C for ITS-gene, 74.2°C for phop gene, 76.49°C for sap-gene, 78.2°C for mvaA gene, 79.57°C for 16srRNA-gene, 74.83°C for mupA gene, and 76.6°C for mecA gene. Conclusions: The MCA based on real time-PCR for identifying staphylococcal species and antibiotic resistance is a highly effective method with high sensitivity and specificity.