Validation of bedaquiline drug-susceptibility testing by BACTEC MGIT 960 system for Mycobacterium tuberculosis

Abstract

Background: Bedaquiline (BDQ) is a new antituberculosis (TB) drug effectively used for the treatment of multidrug-resistant and extensively drug-resistant TB. However, the reports on drug-susceptibility testing (DST) for BDQ are scarce. The study aimed to validate and standardize BDQ DST by BACTEC MGIT 960 system for Mycobacterium tuberculosis. Methods: A panel of ten M. tuberculosis isolates comprising 8 BDQ sensitive and 2 BDQ resistant strains were used to test accuracy, repeatability, and reproducibility of BDQDST by MGIT 960. BDQ DST by Middlebrook 7H11 agar method using polystyrene tubes was used as a standard method to calculate the accuracy of the validation. Results: DST by MGIT for BDQ showed 100% accuracy, repeatability, and reproducibility, although variations were observed in the growth units of the "test" MGIT tubes between technologist and drug stocks while testing for reproducibility. Conclusion: BDQ DST by MGIT 960 system is accurate, repeatable, and reproducible and hence can be implemented in certified laboratories routinely performing DST by MGIT 960 system.