Abstract:

Objective To explore the drug susceptibility of levofloxacin (Lfx), moxifloxacin (Mfx), bedaquiline (Bdq), linezolid (Lzd), clofazimine (Cfz) and delamanid (Dlm) against multidrug-resistant tuberculosis (MDR-TB) isolates from Changping District, and to illustrate the genetic characteristics of MDR-TB isolates with acquired drug resistance, further to provide the basis for clinical drug use, the results of drug resistance gene sequencing were compared with the standard strain. Methods A total of 83 MDR-TB isolates were collected from 2011—2015 in Beijing Changping Center for Tuberculosis Control after culture and strain identification. The minimum inhibitory concentrations (MICs) were used to detect the drug sensitivity of MDR-TB strains, and genes sequence related to drug resistance related genes were amplified and compared with the standard strains. Results Of the 83 MDR-TB isolates, Lfx and Mfx both had the highest resistance rate (41.0%, 34/83). The resistance rate to Bdq was the lowest (2.4%, 2/83). The resistance rate to Lzd, Cfz, and Dlm was 4.8% (4/83), 3.6% (3/83), and 4.8% (4/83), respectively. Among the 39 isolates resistant to Lfx and Mfx, the most prevalent resistance mutation was found in gyrA with the substitution of codon 94 (87.2%, 34/39). All 2 Cfz-Bdq cross resistant strains had a mutation in the Rv0678 gene, 2 of 4 Lzd resistant isolates carried mutations in rplC gene. Of the 4 isolates resistant to Dlm, 1 isolate with mutation in codon 318 of fbiC gene and 2 isolates in codon 81 of ddn gene. Conclusion The resistance of MDR-TB isolates to Lfx/Mfx was high while the lowest resistance rate was observed in Bdq in Beijing Changping District. The anti-TB drug with a low resistance rate should be selected according to the characteristics of MDR-TB patients in this region.

Key words: Mycobacterium tuberculosis, Tuberculosis, multidrug-resistant, Mutation, Genes, Small-area analysis