Department of Medical Microbiology, Mycobacteriology (BSL-3) Laboratory, Makerere University, Kampala, Uganda.
Department of Immunology and Molecular Biology, Makerere University, Kampala, Uganda.
PLoS One. 2020 May 15;15(5):e0232543. doi: 10.1371/journal.pone.0232543. eCollection 2020.
Susceptibility testing for pyrazinamide (PZA), a cornerstone anti-TB drug is not commonly done in Uganda because it is expensive and characterized with technical difficulties thus resistance to this drug is less studied. Resistance is commonly associated with mutations in the pncA gene and its promoter region. However, these mutations vary geographically and those conferring phenotypic resistance are unknown in Uganda. This study determined the prevalence of PZA resistance and its association with pncA mutations.
Using a cross-sectional design, archived isolates collected during the Uganda national drug resistance survey between 2008-2011 were sub-cultured. PZA resistance was tested by BACTEC Mycobacterial Growth Indicator Tube (MGIT) 960 system. Sequence reads were downloaded from the NCBI Library and bioinformatics pipelines were used to screen for PZA resistance-conferring mutations.
The prevalence of phenotypic PZA resistance was found to be 21%. The sensitivity and specificity of pncA sequencing were 24% (95% CI, 9.36-45.13%) and 100% (73.54% - 100.0%) respectively. We identified four mutations associated with PZA phenotypic resistance in Uganda; K96R, T142R, R154G and V180F.
There is a high prevalence of phenotypic PZA resistance among TB patients in Uganda. The low sensitivity of pncA gene sequencing confirms the already documented discordances suggesting other mechanisms of PZA resistance in Mycobacterium tuberculosis.
吡嗪酰胺（PZA）是一种抗结核基石药物，由于其昂贵且具有技术难度，因此在乌干达并不常进行药敏试验，从而对该药物的耐药性研究较少。耐药性通常与 pncA 基因及其启动子区域的突变有关。然而，这些突变在地理上存在差异，在乌干达尚不清楚哪些突变可导致表型耐药。本研究旨在确定 PZA 耐药的流行情况及其与 pncA 突变的关系。
采用横断面设计，对 2008-2011 年乌干达国家耐药性调查期间收集的存档分离株进行了亚培养。采用 BACTEC 分枝杆菌生长指示剂管（MGIT）960 系统检测 PZA 耐药性。从 NCBI 文库下载序列读数，并使用生物信息学管道筛选出 PZA 耐药相关突变。
发现表型 PZA 耐药的流行率为 21%。pncA 测序的灵敏度和特异性分别为 24%（95%CI，9.36-45.13%）和 100%（73.54%-100.0%）。我们在乌干达发现了四种与 PZA 表型耐药相关的突变：K96R、T142R、R154G 和 V180F。
乌干达的结核病患者中存在较高的表型 PZA 耐药率。pncA 基因测序的低灵敏度证实了已有文献记录的不一致性，表明结核分枝杆菌中存在其他 PZA 耐药机制。
