Effects of mutations conferring pyrazinamide resistance among multidrug-resistant tuberculosis isolates from China

To investigate the effects of mutations on pyrazinamide (PZA)-associated regions, including pncA, rpsA, panD, and clpC1, among multidrug-resistant tuberculosis (MDR-TB) isolates from China. A total of 139 MDR-TB isolates from China underwent PZA susceptibility testing and genotyping, and the sequences of the four PZA resistance-associated regions were analyzed. The association between lineage and PZA resistance was analyzed, as well as that between lineage and mutation. Among 139 MDR-TB isolates, 62 were resistant to PZA. Of these 62 PZA-resistant isolates, 60 harbored at least one nonsynonymous mutation in the pncA, rpsA, or clpC1. None of the isolates contained a mutation in panD. Most mutations in PZA-resistant isolates were concentrated in pncA, while mutations in other genes were rare and usually accompanied by mutations in pncA. The single mutation outside pncA observed in a PZA-resistant isolate was a novel rpsA mutation G(-131)A. The mutation Pro796Leu in clpC1 was exclusively detected in lineage 4 strains and correlated with this lineage, but was not associated with PZA resistance. The DNA sequencing of pncA proved to be the most effective approach for detecting PZA resistance, with an accuracy of 92.81%. Notably, some PZA-susceptible isolates still carried mutations in pncA, rpsA, or clpC1. This study highlights the complexity of PZA resistance. These findings expand our understanding of the molecular features associated with PZA resistance in China.

In this study, we systematically investigated the mutations in pyrazinamide (PZA)-resistance-associated genes, including pncA, rpsA, panD, and clpC1, among the multidrug-resistant tuberculosis (MDR-TB) isolates from China, and their effects on the PZA resistance. This study is essential for comprehensively understanding the association between the phenotypic susceptibility to PZA and the mutation patterns in clinical MDR-TB isolates in China and is helpful for designing reliable and rapid molecular diagnostic assays for PZA resistance.