A retrospective cohort study of isoniazid-resistant tuberculosis treatment outcomes and isoniazid resistance-associated mutations in eastern China from 2013 to 2018.

Abstract Background The current situation of rifampicin-susceptible, isoniazid-resistant tuberculosis (Hr-TB) and associated genetic factors were not clear in China. Methods A retrospective cohort study was conducted from 2013 to 2018 in Jiangsu province. The phenotypic Hr-TB was identified by drug susceptibility testing on Lowenstein-Jensen media and Mycobacterium Growth Indicator Tube 960, and the mutations of katG 315 codon and inhA promoter nucleotide -8, -15, -16 were determined by GenoType MTBDRplus and sequencing. All the Hr-TB enrolled were followed up until June of 2019. Results A total of 1416 smear positive TB patients were enrolled and 63 (4.64%) were determined as Hr-TB patients. After following up, 5 (7.94%) Hr-TB cases occurred relapse, 4 (6.35%) with treatment failure and 2 (3.17%) died. In total, 11 (17.46%) Hr-TB proceeded into unfavorable outcomes. As 3 isolates failed in mutation detection, 52 (82.54%) isolates were detected with either katG 315 or inhA promoter nucleotide -8, -15, -16 mutations, and 8 isolates (12.71%) were not found any canonical mutations. TB history was found in association with unfavorable outcomes for Hr-TB (OR = 6.13, 95% CI = 1.05 to 35.82, P = 0.04). However, mutations in katG 315 and inhA promoter region were not found in relationship to Hr-TB unfavorable outcomes (P = 0.15). Conclusion The unfavorable outcomes for Hr-TB were serious in eastern China, especially for previously treated patients. Meanwhile, the current genetic determination of Hr-TB was inadequate.