PURPOSE

This study was designed to identify the phenotypic and genotypic characteristics of pyrazinamide (PZA) resistance among multidrug-resistant (MDR-TB) from Henan and to evaluate the efficacy of , and mutations in predicting PZA resistance.

MATERIALS AND METHODS

A total of 152 MDR strains were included in this study. The Bactec MGIT system was used to determine PZA susceptibility for all strains. The , and genes were sequenced to identify any mutations, and the sequences were then aligned with the sequence of standard strain H37Rv. Moreover, the correlations between PZA-resistant phenotypes and treatment outcomes were analysed.

RESULTS

Of the152 strains, 105 had a PZA-resistant phenotype, and 102 harboured the mutation. The PZA resistance rate was higher in the strains with resistance to all four first-line drugs and those that were pre-extensively drug-resistant (pre-XDR) and extensively drug-resistant (XDR). A total of 100 different mutation patterns were identified, including 80 point mutations and 20 insertions/deletions, and 32 new mutation patterns were detected. In this study, 13 strains had multiple mutations. Of the11 PZA-resistant strains without mutations, two harboured the mutation, and one harboured the mutation. With PZA susceptibility results as the reference, single-gene sequencing had sensitivity of 89.52% and specificity of 89.36%. With the combination of and , the sensitivity increased to 92.38%, and the specificity remained the same. No significant differences were observed in the sputum smear/culture conversion rate between PZA-resistant patients and PZA-sensitive patients. However, PZA resistance was related to the time to sputum smear/culture conversion ( = 0.018).

CONCLUSION

The combination of , and was beneficial for the timely diagnosis of PZA resistance and could provide a laboratory basis for customizing treatment regimens for MDR-TB patients.