Abstract:

Objective To explore the application value of next-generation sequencing (NGS) in the diagnosis of drug-resistant tuberculosis. Methods A total of 150 specimens of bacterial strain were selected from the Year 2016-2017 baseline survey on drug-resistant tuberculosis in Gansu Province, and tested by proportional drug sensitivity test (drug sensitivity test) and NGS of drug resistance-related genes (including katG, inhA, embB, rpoB, rpsL, rrs, gyrA, and gyrB). Two non-tuberculous mycobacteria (NTM) strains were excluded, 13 strains were failed to be sequenced, therefore, 135 strains were finally included. Results of drug sensitivity test were used as standard to evaluate the efficacy of NGS in the diagnosis of drug-resistant tuberculosis. Results Based on drug sensitivity results, sensitivities NGS in detecting isoniazid (INH), ethambutol (EMB), rifampicin (RFP), streptomycin (Sm), and ofloxacin (Ofx) were 88.75% (71/80), 85.71% (18/21), 84.72% (61/72), 73.91% (51/69) and 68.97% (20/29), respectively; and the specificities of the above drugs were 100.00% (55/55), 86.84% (99/114), 96.83% (61/63), 96.97% (64/66), and 99.06% (105/106), respectively; Kappa values were 0.87, 0.59, 0.81, 0.71, and 0.76, respectively. Gene mutations of INH-resistant were mainly in katG 315, with a mutation frequency of 97.18% (69/71); those in EMB) were in embB 306, with a mutation frequency of 88.89% (16/18); those in RFP were in the resistance-determining area, with a mutation frequency of 93.65% (59/63); those of Sm were in rpsL 43, with a mutation frequency of 79.25% (42/53); and those in Ofx were in gyrA 94, with a mutation frequency of 76.19% (16/21). Conclusion The efficacies of NGS in detecting RFP, INH and Ofx were high and could meet the needs of clinical diagnosis of tuberculosis; while the efficacies of NGS in detecting EMB and Sm were low, and further investigation of the mechanism of drug resistance of the two drugs was needed.

Key words: Mycobacterium tuberculosis, Microbial sensitivity tests, Tuberculosis, multidrug-resistant, Point mutation, Diagnosis, Evaluation studies