Association between overexpression of efflux pumps genes Rv0191 and Rv3008 and pyrazinamide resistance in multidrug-resistant Mycobacterium tuberculosis: a multi-center study

Pyrazinamide is a drug that helps shorten the duration of tuberculosis treatment. Mutations in the pncA are the most common mechanism of pyrazinamide resistance in M. tuberculosis. This study aimed to investigate the association between overexpression of Efflux pump genes Rv0191 and Rv3008 and pyrazinamide resistance in multidrug-resistant M. tuberculosis in a multicenter setting. In this study, 40 clinical isolates of pulmonary M. tuberculosis were gathered from septum specimens; confirmation of M.tuberculosis isolates was achieved by PCR and phenotypic methods using the IS6110 gene. The phenotypic microdilution broth method was evaluated for drug susceptibility testing. Frequency of pncA gene mutations associated with pyrazinamide resistance by the PCR method in M. tuberculosis isolates. The evaluation of the Rv0191 and Rv3008 efflux pump genes was performed on pyrazinamide-sensitive, pyrazinamide-resistant, and multidrug-resistant M. tuberculosis isolates. This study showed that, in MDR, resistance to pyrazinamide was associated with single-resistant strains and a high percentage of mutations in the pncA gene. The most effective method for detecting pyrazinamide resistance is sequencing the entire pncA gene to confirm resistance, rather than the conventional techniques that focus on mutated hotspots. The study found that PZA resistance was common among MDR-TB isolates, with mutations occurring in the pcnA gene. The findings also showed that drug resistance in clinical isolates of M. tuberculosis is often associated with increased expression of efflux pump genes and mutations in target genes. In cases where there are no mutations, resistance may be related to overexpression of other efflux pumps.