Evaluating the Frequency of Resistance to Pyrazinamide Among Drug-resistant Strains of Mycobacterium tuberculosis in Isfahan, Iran

 Pyrazinamide is one of the most important first-line medications for the treatment of tuberculosis and an alternative intake for MDR-TB and XDR-TB patients.

 The purpose of this study was to evaluate resistance to pyrazinamide in the isolates resistant to the Mycobacterium tuberculosis drug in patients in the city of Isfahan.

 In this study, the drug susceptibility test was performed with pyrazinamide using the proportion method and PZA assay on 47 isolates resistant to Mycobacterium tuberculosis. Then, the mutations of the pncA and rpsA genes of the isolates resistant to pyrazinamide were evaluated by the sequencing method.

 According to the proportion method, 19 cases were resistant to pyrazinamide, 16 of which had mutations in their pncA and rpsA genes. Besides, five new mutations were recorded, and three isolates lacked mutations in the mentioned genes.

 Pyrazinamide resistance is high in MDR-TB and INH mono-resistant isolates. Therefore, evaluating the susceptibility to pyrazinamide in patients with MDR-TB before the initiation of treatment with pyrazinamide is considered essential.