Department of Microbiology, Mbarara University of Science and Technology, Box 1410, Mbarara, Uganda.
Department of Microbiology and Immunology, Kampala International University Western Campus, Box 71, Bushenyi, Uganda.
Sci Rep. 2022 Jan 31;12(1):1656. doi: 10.1038/s41598-022-05591-3.
Infections with multiple strains of Mycobacterium tuberculosis are now widely recognized as a common occurrence. Identification of patients infected with multiple strains provides both insight into the disease dynamics and the epidemiology of tuberculosis. Analysis of Mycobacterial Interspersed Repetitive Unit-Variable-Number Tandem Repeats (MIRU-VNTR) has been shown to be highly sensitive in detecting multiple M. tuberculosis strains even in sputum. The goal of this study was to identify cases of multiple M. tuberculosis strain infections among patients diagnosed with pulmonary tuberculosis in Southwestern Uganda and assessment of factors associated with multiple strain infections. DNA extracted directly from 78 sputum samples, each from an individual patient, was analyzed using the standard 24 loci MIRU-VNTR typing. Five (6.4%) of the 78 patients were infected with multiple strains of M. tuberculosis with all of them being the newly diagnosed cases while two-thirds of them were co-infected with HIV. Exact regression analysis projected that the natives were more likely to harbor multiple strains (OR; 0.981, 95% CI 0-7.926) as well as those with a high microbial load (OR; 0.390, 95% CI 0-3.8167). Despite these findings being not statistically significant due to the small sample size, this points to a critical component of disease dynamics that has clinical implications and emphasizes a need for a study using a larger cohort. It is also essential to study the potential factors associated with higher risk of exposure to newly diagnosed and HIV positive patients at the community level. In addition, our ability to detect multiple M. tuberculosis strains using the standard 24 loci MIRU-VNTR typing especially with allelic diversity in loci 2059 and 3171, which are excluded from the 15-locus MIRU-VNTR, lead us to recommend the use of this genotyping technique, especially in areas with tuberculosis endemicity similar to this study.
现在普遍认为，感染多种结核分枝杆菌菌株是很常见的。鉴定感染多种菌株的患者，既能深入了解结核病的发病机制和流行病学，也能提供有关结核分枝杆菌的信息。分析分枝杆菌散在重复单位-可变数串联重复（MIRU-VNTR）已被证明在检测痰液中的多种结核分枝杆菌菌株方面非常敏感。本研究的目的是鉴定在乌干达西南部被诊断为肺结核的患者中存在的多种结核分枝杆菌菌株感染病例，并评估与多种菌株感染相关的因素。直接从 78 份个体患者的痰液样本中提取 DNA，使用标准的 24 个位点 MIRU-VNTR 分型进行分析。78 名患者中有 5 名（6.4%）感染了多种结核分枝杆菌菌株，所有这些患者都是新诊断的病例，其中三分之二合并感染了 HIV。确切回归分析预测，本地人更有可能携带多种菌株（OR；0.981，95%CI 0-7.926）以及那些具有高微生物负荷的菌株（OR；0.390，95%CI 0-3.8167）。尽管由于样本量小，这些发现没有统计学意义，但这表明这是疾病动态的一个关键组成部分，具有临床意义，并强调需要使用更大的队列进行研究。在社区层面上，还需要研究与新诊断和 HIV 阳性患者接触的潜在风险因素。此外，我们使用标准的 24 个位点 MIRU-VNTR 分型检测多种结核分枝杆菌菌株的能力，特别是在排除了 15 个位点 MIRU-VNTR 的位点 2059 和 3171 的等位基因多样性方面，这使我们建议使用这种基因分型技术，特别是在与本研究类似的结核病流行地区。
