Das Sulochana D, Narayanan Sujatha, Hari Lalitha, Hoti S L, Thangathurai R K, Charles Niruparani, Jaggarajamma K, Narayanan P R
Tuberculosis Research Centre (ICMR), Mayor V.R. Ramanathan Road, Chetput, Chennai 600 031, India.
Infect Genet Evol. 2005 Jan;5(1):67-77. doi: 10.1016/j.meegid.2004.06.007.
We have prospectively analysed the DNA fingerprinting of Mycobacterium tuberculosis strains in a rural community from high prevalence area in South India with an ongoing DOTS programme. Strains from 451 culture-positive cases, diagnosed during July 1999-December 2000, were fingerprinted initially by both IS6110 and DR probes followed by polymorphic GC-rich repeat sequences (PGRS) typing only on low-copy strains. The results were correlated with selected epidemiological and clinical data. Forty one percent of strains showed single copy of IS6110, which further got differentiated into 62 DR and 27 PGRS patterns. One predominant DR pattern (5B/2) was found in 20% of the low-copy strains and was also involved in clusters. In all, 183 patients out of 451 (40%) were clustered in total 44 clusters when analysed by IS6110 and DR probes. With additional PGRS typing, the number of patients clustered was further reduced to 106 (23%). More number of patients (131) were clustered in IS6110 single-copy group. The maximum number of clusters was found with two or three patients. Only a small percentage (16%) of the patients reported direct epidemiological links while remaining patients might have had indirect links or casual contacts. Thus, a combination of two to three genetic markers is able to differentiate the most endemic strains of M. tuberculosis in areas with a high incidence of tuberculosis. The epidemiological data do not suggest any major outbreaks or a hot-spot hypothesis of transmission in this region. Phylogenetic analysis using IS6110, DR and PGRS RFLP (restriction fragment length polymorphism, RFLP) fingerprints showed that isolates exhibited clonal evolutionary pattern. The predominance of certain genotypes and agreement between the phylogenetic trees indicated that these strains were closely related and might have evolved or propagated from the common ancestor.
我们前瞻性地分析了印度南部高流行地区一个实施直接观察短程化疗（DOTS）项目的农村社区中结核分枝杆菌菌株的DNA指纹图谱。对1999年7月至2000年12月期间诊断出的451例培养阳性病例的菌株，首先使用IS6110和DR探针进行指纹图谱分析，随后仅对低拷贝菌株进行富含GC的多态性重复序列（PGRS）分型。将结果与选定的流行病学和临床数据进行关联分析。41%的菌株显示IS6110单拷贝，这些菌株进一步分化为62种DR和27种PGRS模式。在20%的低拷贝菌株中发现一种主要的DR模式（5B/2），并且该模式也存在于聚类中。通过IS6110和DR探针分析，451例患者中有183例（40%）总共聚集在44个聚类中。增加PGRS分型后，聚集患者数量进一步减少至106例（23%）。IS6110单拷贝组中聚集的患者数量更多（131例）。聚类中患者数量最多的是两到三人。只有一小部分（16%）患者报告有直接的流行病学关联，其余患者可能有间接关联或偶然接触。因此，两到三种遗传标记的组合能够区分结核病高发地区最流行的结核分枝杆菌菌株。流行病学数据未表明该地区有任何重大疫情或传播热点假说。使用IS6110、DR和PGRS限制性片段长度多态性（RFLP）指纹图谱进行的系统发育分析表明，分离株呈现克隆进化模式。某些基因型的优势以及系统发育树之间的一致性表明，这些菌株密切相关，可能从共同祖先进化或传播而来。
