High-resolution melt curve analysis for rapid detection of rifampicin resistance in mycobacterium tuberculosis: A single-center study in Iran

Introduction: Tuberculosis (TB) remains a leading cause of death worldwide, especially in developing countries. Early detection of resistance is extremely important to reduce the risk of death. This study was aimed to compare the diagnostic accuracy of high resolution melting (HRM) analysis in comparison with Xpert MTB/RIF as well as conventional drug susceptibility testing (DST) for the detection of rifampicin (RIF) resistance in Mycobacterium tuberculosis in Iran. Materials and methods: A comparative cross-sectional study was carried out from April 2017 to September 2018. A total of 80 culture-positive clinical samples selected during the study period were analyzed for detection of RIF-resistant TB by conventional DST, Xpert MTB/RIF, and sequencing. Sensitivity and specificity of the HRM calculated according to DST as our gold standard test in this study. Results: The overall sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of HRM assay were found to be 100%, 89.33%, 38.46%, and 100% respectively. Conclusions: The analysis has demonstrated that the diagnostic accuracy of HRM tests is insufficient to replace Xpert MTB/RIF and conventional DST. HRM test may be used in combination with culture due to the advantage of the time to result. Further work to improve molecular tests would benefit from standardized reference standards and the methodology.