Identification of mutations associated with Macozinone-resistant in Mycobacterium Tuberculosis

Macozinone is identified as a drug candidate and is currently under clinical development for the treatment of tuberculosis, but the mutations conferring resistance to Macozinone remain inadequately characterized. Herein, we investigated the Macozinone -resistance -associated mutations through selecting resistant isolates in vitro. Macozinone-resistant isolates were obtained through induction in vitro. The level of Macozinone -resistant strains was confirmed by MABA test. PCR sequencing analysis was carried out on dprE1 gene. Whole Genome Sequencing was performed to identify mutations associated with Macozinone -resistance. The totals of isolates obtained at Macozinone concentrations of 6.4ng/ml, 25.6ng/ml, 50ng/ml and 100ng/ml were 49, 20, 20 and 4 respectively. Among the 49 strains obtained by 6.4ng/ml Macozinone only one strain had C387S mutation in dprE1. C387S is only occurred in high-level resistant isolates (MIC > 500ng/ml). Meanwhile high-level resistance to Macozinone can occur in strains induced at 6.4ng/ml and the frequency of occurrence is low (1/49, 2.04%). The MIC90 of other strains except the strains carrying C387S mutation is at the same level (11.5ng/ml > MIC90 > 2ng/ml). The G61A or G248A mutations in dprE1 was discovered for the first time. Other gene mutations (rv0678, rrs, mbtF, rv2956, et al) were found in low-level resistant strains. ConclusionsHigh-level resistant isolates can be produced at low concentration of Macozinone. C387S mutation in dprE1 is directly related to high-level resistance. There may be new mechanisms involved in Macozinone-resistance independent of dprE1 mutations.