Tropical Diseases Research Center, Ndola, Zambia.
BMC Infect Dis. 2010 Jun 17;10:177. doi: 10.1186/1471-2334-10-177.
Tuberculosis (TB) is one of the major public health problems in Zambia. However, information about lineages of M. tuberculosis complex (MTBC) isolates useful for epidemiology investigations is unknown. In this study, we investigated the diversity of MTBC isolates from Ndola, a typical Zambian urbanized city with a documented high HIV prevalence.
This was part of a prospective cohort study in subjects with sputum smear-positive pulmonary TB. Spoligotyping was used to genotype the MTBC isolates and establish the circulating lineages. The 15-locus Mycobacterial Interspersed Repetitive Units - Variable Number Tandem Repeats (MIRU-VNTR) typing was used to study recent transmission.
A total of 98 different spoligotypes were identified among 273 MTBC isolates. The majority (64.8%) of the isolates belonged to 9 known families, while 96 (35.2%) of the isolates were orphans. While LAM (41.8%) was the largest spoligotype family observed, most of the isolates (87.7%) belonging to the SAF1 family, with a significant portion coming from the T (13.6%), and X (5.9%) families. A few isolates (3.6%) belonged to the CAS, EAI, H, S, X1-LAM9 or U families. MIRU-VNTR typing was highly discriminatory (h = 0.988) among the 156 isolates tested in our sample, and increased the discrimination among 82 SAF1 isolates from 6 to 46 distinct patterns. In addition, 3.2% (5/156) of cases with available MIRU-VNTR results harbored more than one MTBC strain.
Our findings show a limited diversity of MTBC in Ndola with a high clustering rate (37.7%), which indicates that recent transmission plays an appreciable role in the dynamics of TB disease in this setting. This conclusion emphasizes the importance of early diagnosis and timely treatment. The results also confirm that MIRU-VNTR typing is suitable for studying the molecular epidemiology of TB in Ndola.
结核病（TB）是赞比亚主要的公共卫生问题之一。然而，有关对流行病学研究有用的结核分枝杆菌复合群（MTBC）分离株系的信息尚不清楚。在这项研究中，我们调查了恩多拉市 MTBC 分离株的多样性，恩多拉是一个典型的赞比亚城市化城市，有记录表明 HIV 流行率很高。
这是一项在痰涂片阳性肺结核患者中进行的前瞻性队列研究的一部分。 spoligotyping 用于对 MTBC 分离株进行基因分型，并确定流行株系。使用 15 个基因座分枝杆菌插入重复单元-可变数量串联重复（MIRU-VNTR）分型来研究近期传播。
在 273 株 MTBC 分离株中，共鉴定出 98 种不同的 spoligotype。大多数（64.8%）分离株属于 9 个已知家族，而 96（35.2%）个分离株为孤儿。虽然 LAM（41.8%）是观察到的最大 spoligotype 家族，但大多数（87.7%）属于 SAF1 家族，其中很大一部分来自 T（13.6%）和 X（5.9%）家族。少数分离株（3.6%）属于 CAS、EAI、H、S、X1-LAM9 或 U 家族。在我们样本中测试的 156 个分离株中，MIRU-VNTR 分型具有高度的区分力（h=0.988），并将 82 个 SAF1 分离株的区分度从 6 增加到 46 个不同的模式。此外，在有可用 MIRU-VNTR 结果的 5/156 例病例中，有 3.2%（5/156）的病例携带不止一种 MTBC 株。
我们的研究结果表明，恩多拉市的 MTBC 多样性有限，聚类率较高（37.7%），这表明近期传播在该环境中结核病疾病的动态中起着相当大的作用。这一结论强调了早期诊断和及时治疗的重要性。结果还证实，MIRU-VNTR 分型适合研究恩多拉的结核病分子流行病学。
