Shi Dawei, Zhou Qiulong, Xu Sihong, Zhu Yumei, Li Hui, Xu Ye
National 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.
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.
Infect Drug Resist. 2022 Aug 30;15:4985-4994. doi: 10.2147/IDR.S368444. eCollection 2022.
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 of 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 isolates.
An evaluation of 82 MDR 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 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 mutations and PZA resistance was significant under 100 and 300 mg/L. The sensitivity of 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.
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.
吡嗪酰胺（PZA）是结核病（TB）标准化化疗的关键组成部分，推荐用于治疗耐多药（MDR）结核病。我们旨在鉴定中国结核分枝杆菌（MTB）中pncA基因的突变，并评估其对PZA敏感性的诊断准确性。我们还将基因型方法与表型药敏试验和吡嗪酰胺酶（PZAse）活性相结合，以确认耐PZA的MTB分离株。
对82株MDR MTB菌株的评估显示，28.0%（23/82）对100 mg/L PZA表型耐药，15.9%（13/82）对300 mg/L PZA耐药。在33个独特位点检测到pncA基因突变，大多数为点突变。未发现明显的突变热点或影响多个氨基酸的突变，但在100 mg/L和300 mg/L浓度下，pncA基因突变与PZA耐药之间的关联显著。基于100 mg/L PZA，pncA基因突变检测预测PZA敏感性的灵敏度为82.6%（19/23），特异性为61.0%（36/59）；而基于300 mg/L PZA，灵敏度为84.6%（11/13），特异性为55.1%（38/69）。在高度耐PZA（300 mg/L）菌株中鉴定出的所有突变相对于PZAse活性均有80%的损失。在一株同义突变菌株中未观察到明显的PZAse活性损失，而在所有其他菌株中损失超过60%。
pncA基因突变与PZA耐药之间的关联显著。相对而言，分子方法在检测PZA耐药性方面比表型方法具有更好的可靠性。这为耐多药结核病的临床诊断提供了理论依据。
