Plasmid-based high-resolution melting analysis for accurate detection of rpoB mutations in Mycobacterium tuberculosis isolates from Moroccan patients

BACKGROUND Rapid diagnosis of drug resistance in tuberculosis (TB) is pivotal for the timely initiation of effective antibiotic treatment to prevent the spread of drug-resistant strains. The development of low-cost, rapid and robust methods for drug-resistant TB detection is highly desirable for resource-limited settings. METHODS We report the use of an in house plasmid-based quantitative polymerase chain reaction-high-resolution melting (qPCR-HRM) analysis for the detection of mutations related to rifampicin-resistant Mycobacterium tuberculosis (MTB) in clinical isolates from Moroccan patients. Five recombinant plasmids containing predominant mutations (S531L, S531W, H526Y and D516V) and the wild-type sequence of the Rifampicin Resistance-Determining Region (RRDR) have been used as controls to screen 45 rifampicin-resistant and 22 rifampicin-susceptible MTB isolates. RESULTS The sensitivity and the specificity of the qPCR-HRM analysis were 88.8% and 100% respectively as compared to rifampicin Drug Susceptibility Testing (DST). The results of qPCR-HRM and DNA sequencing had a concordance of 100%. CONCLUSION Our qPCR-HRM assay is a sensitive, accurate and cost-effective assay for the high-throughput screening of mutation-based drug resistance in TB reference laboratories.