Pyrazinamide Resistance and pncA Mutation Profiles in Multidrug Resistant Mycobacterium Tuberculosis

Abstract

Dawei Shi,1,* Qiulong Zhou,2,* Sihong Xu,1 Yumei Zhu,3 Hui Li,4 Ye Xu2 1National Institutes for Food and Drug Control, Institute of Pathogen Biology at the Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, People’s Republic of China; 2Engineering Research Centre of Molecular Diagnostics of the Ministry of Education, State Key Laboratory of Cellular Stress Biology, State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Life Sciences, Xiamen University, Xiamen, People’s Republic of China; 3Shenzhen Center for Chronic Disease Control, Shenzhen, People’s Republic of China; 4Tuberculosis Reference Laboratory, Henan Provincial Centers for Disease Control and Prevention, Zhengzhou, People’s Republic of China*These authors contributed equally to this workCorrespondence: Hui Li, Tuberculosis Reference Laboratory, Henan Provincial Centers for Disease Control and Prevention, Zhengzhou, People’s Republic of China, Tel/Fax [phone], Email [email protected] Ye Xu, Engineering Research Centre of Molecular Diagnostics of the Ministry of Education, State Key Laboratory of Cellular Stress Biology, State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Life Sciences, Xiamen University, Xiamen, People’s Republic of China, Tel [phone], Fax [phone], Email [email protected]: Pyrazinamide (PZA) is a critical component of standardized chemotherapy for tuberculosis (TB) and is recommended for the treatment of multidrug-resistant (MDR) TB. We aimed to characterize mutations in pncA of M. tuberculosis and evaluate their diagnostic accuracy for PZA susceptibility in China. We also combined genotypic methods with phenotypic susceptibility testing and pyrazinamidase (PZAse) activity to confirm PZA-resistant M. tuberculosis isolates.Results: An evaluation of 82 MDR M. tuberculosis strains revealed that 28.0% (23/82) were phenotypically resistant to 100 mg/L PZA and 15.9% (13/82) showed resistance to 300 mg/L PZA. Mutations in pncA were detected at 33 unique sites, and the majority were point mutations. No evident mutation hotspots or mutations affecting multiple amino acids were found, but the association between pncA mutations and PZA resistance was significant under 100 and 300 mg/L. The sensitivity of pncA mutation detection for predicting PZA susceptibility was 82.6% (19/23), and the specificity was 61.0% (36/59), based on 100 mg/L PZA, whereas the sensitivity was 84.6% (11/13) and the specificity was 55.1% (38/69), based on 300 mg/L PZA. All mutations identified in the highly PZA-resistant (300 mg/L) strains had an 80% loss relative to PZAse activity. No evident PZAse activity loss was observed in one synonymous mutation strain and the loss exceed 60% in all other strains.Conclusion: The association between pncA mutation and PZA resistance was significant. Relatively, the molecular method have shown better reliability than the phenotypic method for the detection of PZA resistance. This provides a theoretical basis for the clinical diagnosis of drug-resistant TB.Keywords: MDR, PZA, pncA, DST, Beijing genotype, enzymatic activity

Keywords

• mdr
• pza
• pnca
• dst
• beijing genotype
• enzymatic activity