Molecular epidemiology of Mycobacterium tuberculosis isolates from Kerala,India using IS6110-RFLP,spoligotyping and MIRU-VNTRs

Tuberculosis (TB) continues to be a major health problem in India, and there is very little information about the prevalent genotypes of tubercle bacilli that cause TB in India, especially in Kerala. Our aim was to study the different circulating strains of Mycobacterium tuberculosis (MTB) that are prevalent in Kerala, India. We analyzed 168 MTB isolates from as many pulmonary TB patients using IS6110-RFLP, spoligotyping and MIRU-VNTRs. The results of IS6110-RFLP revealed that majority of isolates had null copy (10.89%) or single copy (44.87%) of IS6110 insertion. Low copy (<6) isolates accounted for 71.5% in the isolates studied. Genotypic clade designations were done by comparing with the SITVIT2 database which showed 68 patterns; of which 51 corresponded to different shared types whereas 17 patterns were orphans. Among the 51 SITs recorded, 42 SITs matched a preexisting SIT in the SITVIT2 database, whereas 9 SITs were newly-created. Majority of the isolates (64.28%) belonged to the ancestral East-African Indian (EAI) lineage. MIRU-40 and 31 (HGDI = 0.6555 and 0.6524) showed highest discrimination, while MIRU-2 and 20 (HGDI = 0.0354 and 0.0696) had the least discriminatory power. ETR-A and B (HGDI 0.7382 and 0.6743) discriminated better as compared to other MIRU loci. The overall HGDI for MIRU-VNTRs at 0.9735 (calculated for 166 isolates) showed a better discriminatory power than spoligotyping used alone. This study of MTB genotypic diversity was useful by providing a first snapshot of circulating MTB genotypic clones in Kerala.     

Molecular typing of Mycobacterium tuberculosis isolates from a rural area of Kanpur by spoligotyping and mycobacterial interspersed repetitive units (MIRUs) typing.

Molecular typing of Mycobacterium tuberculosis isolates has greatly facilitated the understanding of epidemiology of tuberculosis (TB). This study was done to characterize prevalent genotypes of M. tuberculosis on a collection of 97 isolates based on spoligotyping and mycobacterial interspersed repetitive units-variable number of tandem repeats (MIRU-VNTR) typing in rural area of Kanpur, North India. In this area different types of interventions are being undertaken and follow-up studies are progressing. Predominant spoligotypes prevalent in this region belonged to Central Asian-Delhi family (CAS1_Del) (37%), East African-Indian family (11%), T1 family (8%) and Beijing (4%) family. Highly distinct MIRU-VNTR genotypes were obtained. Significant spoligotypes such as Beijing and CAS1_Del type were further divided into subtypes with MIRU-VNTR. This preliminary study reveals that CAS is the most predominant family in this rural area of Kanpur. If confirmed in other areas, this combined approach of molecular typing can be preferably be used as first line tool for studying linkage and transmission dynamics of TB in India.     

Anthrax molecular epidemiology and forensics: using the appropriate marker for different evolutionary scales.

Precise identification of Bacillus anthracis isolates has aided forensic and epidemiological analyses of natural anthrax cases, bioterrorism acts and industrial scale accidents by state-sponsored bioweapons programs. Because there is little molecular variation among B. anthracis isolates, identifying and using rare variation is crucial for precise strain identification. We think that mutation is the primary diversifying force in a clonal, recently emerged pathogen, such as B. anthracis, since mutation rate is correlated with diversity on a per locus basis. While single nucleotide polymorphisms (SNPs) are rare, their detection is facilitated by whole genome discovery approaches. As highly stable phylogenetic markers, SNPs are useful for identifying long branches or key phylogenetic positions. Selection of single, diagnostic "Canonical SNPs" (canSNPs) for these phylogenetic positions allows for efficient and defining assays. We have taken a nested hierarchal strategy for subtyping B. anthracis, which is consistent with traditional diagnostics and applicable to a wide range of pathogens. Progressive hierarchical resolving assays using nucleic acids (PHRANA) uses a progression of diagnostic genomic loci that are initially highly stable but with low resolution and, ultimately, very unstable but with high resolution. This approach mitigates the need for data weighting and provides both a deeply rooted phylogenetic hypothesis and high resolution discrimination among closely related isolates.     

上海市2000-2002年91株结核分枝杆菌分子流行病学分析

目的探讨上海地区结核病分子流行病学特点。方法对从上海市疾病预防控制中心菌株库中随机抽取的2000—2002年各50株耐药和敏感菌株进行间隔区寡核苷酸分型（Spoligotyping）和分枝杆菌散在分布重复单位（MIRU）基因型分型，并结合流行病学资料进行分析。结果抽样菌株中，具有特异Spoligotyping指纹图谱的北京基因型菌株在上海地区分布达89％（81／91）。未接种过卡介苗（BCG）的患者中北京基因型菌株占88．5％（54／61），接种过BCG的患者中北京基因型菌株占90％（27／30），差异无统计学意义。北京基因型菌株耐药率为45．7％（37181），低于非北京基因型菌株的耐药率60．0％（6／10），差异无统计学意义。MIRU成簇菌株占所有菌株的62．6％（57／91）。结论北京基因型菌株在上海地区有广泛分布，北京基因型菌株与BCG接种和耐药无关，结核病患者中有部分是由于近期传播而引起的。     

应用MLVA技术对吉林省294株结核分枝杆菌分型分析

目的初步探讨利用VNTR（variable number of tandem repeat）技术对吉林省294株结核分枝杆菌分型的分布特征。方法采用多位点串联重复序列（MLVA）分型方法初步选取13个分型效果较好的VNTR基因位点,采用聚合酶链反应（PCR）和琼脂糖凝胶电泳,通过BioNumerics（Versiort3．0）软件进行处理,分析吉林省耐药结核分枝杆菌的DNA多态性。结果共对294株结核分枝杆菌的13个VNTR位点进行了检测,根据这些菌株的指纹多态性特征,主要分成13个型,其中占据主要的前三型分别为I型,占81．6％（240／294）,二型占2．1％（6／294）,三型占1．7％（5／294）,由此可以看出本次实验菌株除I型以外,其他菌株基本呈散在分布。结论分析表明吉林省结核分枝杆菌以I型菌株为主,应加强此型菌株流行的监控及研究。     

Multidrug-resistant Mycobacterium tuberculosis: molecular perspectives.

Multidrug-resistant strains of Mycobacterium tuberculosis seriously threaten tuberculosis (TB) control and prevention efforts. Molecular studies of the mechanism of action of antitubercular drugs have elucidated the genetic basis of drug resistance in M. tuberculosis. Drug resistance in M. tuberculosis is attributed primarily to the accumulation of mutations in the drug target genes; these mutations lead either to an altered target (e.g., RNA polymerase and catalase-peroxidase in rifampicin and isoniazid resistance, respectively) or to a change in titration of the drug (e.g., InhA in isoniazid resistance). Development of specific mechanism-based inhibitors and techniques to rapidly detect multidrug resistance will require further studies addressing the drug and drug-target interaction.     

Molecular epidemiology of tuberculosis in Prague and South Moravia, Czech Republic: genetic analysis of Mycobacterium tuberculosis isolates by IS6110-RFLP fingerprinting and spoligotyping

OBJECTIVES: To genetically characterize and compare Mycobacterium tuberculosis isolates among culture-confirmed TB cases in two regions in the Czech Republic in 1998. METHODS: Consecutive M. tuberculosis isolates from 111 TB patients in Prague and 120 patients in the South Moravia region were genotyped using the standardized IS6110 Southern blot hybridization method and by spoligotyping. RESULTS: Eighty of the Prague patients (72.1%) had isolates with unique RFLP patterns, while 31 (27.9%) had isolates which belonged to 10 clusters. Seventy-eight (64.7%) of the South Moravia strains displayed unique RFLP pattern and 42 (35.3%) were assigned into 15 clusters. The spoligotype profiles previously identified in the U.S. were found in 69 (33%) samples and newly identified Czech spoligotypes in 24 (11.4%) of the total number of examined strains. CONCLUSIONS: The present population-based molecular epidemiological study performed in two regions of the Czech Republic in 1998 demonstrated the distribution of individual genotypes as well as clustered strains of M. tuberculosis isolated from TB patients, and confirmed the similarity between the Czech strain collection and the European Community TB Database, that includes countries with low TB rate. The sporadic import of TB cases from foreign countries and recent transmission events probably do not play significant roles in the epidemiological situation in the Czech Republic.     

Population genetics of Mycobacterium tuberculosis complex in Scotland analysed by pulsed-field gel electrophoresis.

The results of typing of 121 strains in the Mycobacterium tuberculosis complex by PFGE are presented. Every isolate from patients in Scotland over a 3-month period for M. tuberculosis and for 1 year for M. bovis were included along with several laboratory strains including those of BCG. The PFGE results suggest that the population structure of all the strains in this complex is distinctly simple with limited genetic diversity and also suggest that M. bovis is not a distinct species.     

Insights into the population structure of Mycobacterium tuberculosis using spoligotyping and RDRio in a southeastern Brazilian prison unit

Tuberculosis (TB) is still a serious public health problem, continuing to be an important threat for confined populations. We used spoligotyping to estimate the genotypic clades of Mycobacterium tuberculosis isolates from inmates in two blocks in a southeastern Brazilian prison unit, with TB incidence rate of 8185/100.000. The Latin American Mediterranean (LAM) clade is well represented in the country, and the LAM specific molecular markers, RD^Rio large sequence polymorphism and the SNP on the Rv3062 [ligB¹²¹²], were used to characterize spoligotype signatures from prison isolates. Typing of RD^Rio and ligB increase LAM clade from 66.7% (n = 72/108) to 69.4% (n = 75). The LAM2 SIT17 (n = 23) and SIT179 (n = 12) signatures comprised one third of all isolates, followed by Haarlem (11.5%, n = 12), T (8.7%, n = 9) and X (5.7%, n = 6) clades. Strains with unknown signatures represented 5.5% (n = 6), and four (3.7%) did not match any lineage. We observed RD^Rio among 64 (59.2%) isolates, and 54 (50%) were of the LAM clade. In particular, the LAM2/RD^Rio sub-lineage was significantly associated with clustering (p = 0.02) and its frequency was higher (32%) when compared to that of the previous general TB cases in RJ (4.29%). Overall cluster frequency defined by spoligotyping/IS6110-RFLP was 62%. The two evolutionary markers helped to evaluate some LAM signature misconceptions and demonstrate that LAM2/RD^Rio was found with high frequency, hitherto being unnoticed. All these data, allied to high clustering, imply that public health measures to minimize the escalation of TB in prison is essential, and both spoligotyping as well as RD^Rio would be useful tools to monitor the effects of the measures with respect to M. tuberculosis lineage variation.     

Interpreting genotype cluster sizes of Mycobacterium tuberculosis isolates typed with IS6110 and spoligotyping

Molecular techniques such as IS6110-RFLP typing and spacer oligonucleotide typing (spoligotyping) have aided in understanding the transmission patterns of Mycobacterium tuberculosis. The degree of clustering of isolates on the basis of genotypes is informative of the extent of transmission in a given geographic area. We analyzed 130 published data sets of M. tuberculosis isolates, each representing a sample of bacterial isolates from a specific geographic region, typed with either or both of the IS6110-RFLP and spoligotyping methods. We explored common features and differences among these samples. Using population models, we found that the presence of large clusters (typically associated with recent transmission) as well as a large number of singletons (genotypes found exactly once in the data set) is consistent with an expanding infectious population. We also estimated the mutation rate of spoligotype patterns relative to IS6110 patterns and found the former rate to be about 10-26% of the latter. This study illustrates the utility of examining the full distribution of genotype cluster sizes from a given region, in the light of population genetic models.     

Contribution of spoligotyping to the characterization of the population structure of Mycobacterium tuberculosis isolates in Portugal.

Tuberculosis is a major health problem in Portugal. To begin characterizing the population structure of Mycobacterium tuberculosis, spoligotyping was used for the systematic typing, through consecutive sampling, of patient isolates from the Amadora-Sintra area of Greater Lisbon. Distribution amongst major spoligotype families, including the Latin American Mediterranean (LAM), T, Haarlem and Beijing, was compared to that of the international spoligotype database SpolDB4 and to the European countries of traditional Portuguese immigration represented in SpolDB4. Spoligotypes from 665 isolates were analyzed and 97 shared international types (SITs) identified. In SpolDB4 Portugal is represented by part of the spoligotypes from this study explaining the reduced number of unidentified patterns. The importance of the LAM family, and especially of LAM1 and LAM9 sub-families that alone represented 38% of all the isolates in this study as compared to 8% relative to the European sub group, led us to believe that at least in this respect the population structure was closer to that of Africa and South America than to Europe. Spoligotypes characteristic of Portugal or Portuguese related settings were identified. These included SIT244 a T1 sub-family predominant in Portugal and Bangladesh, SIT64 a LAM 6 sub-family common to Portugal and Brazil, and SIT1106 a LAM 9 sub-family. These studies were the first in Portugal stressing the importance of monitoring the population structure of M. tuberculosis isolates, an important step towards gaining an understanding of tuberculosis and the dynamics of this disease.     

SITVITWEB--a publicly available international multimarker database for studying Mycobacterium tuberculosis genetic diversity and molecular epidemiology

Among various genotyping methods to study Mycobacterium tuberculosis complex (MTC) genotypic polymorphism, spoligotyping and mycobacterial interspersed repetitive units-variable number of DNA tandem repeats (MIRU-VNTRs) have recently gained international approval as robust, fast, and reproducible typing methods generating data in a portable format. Spoligotyping constituted the backbone of a publicly available database SpolDB4 released in 2006; nonetheless this method possesses a low discriminatory power when used alone and should be ideally used in conjunction with a second typing method such as MIRU-VNTRs for high-resolution epidemiological studies. We hereby describe a publicly available international database named SITVITWEB which incorporates such multimarker data allowing to have a global vision of MTC genetic diversity worldwide based on 62,582 clinical isolates corresponding to 153 countries of patient origin (105 countries of isolation). We report a total of 7105 spoligotype patterns (corresponding to 58,180 clinical isolates) - grouped into 2740 shared-types or spoligotype international types (SIT) containing 53,816 clinical isolates and 4364 orphan patterns. Interestingly, only 7% of the MTC isolates worldwide were orphans whereas more than half of SITed isolates (n=27,059) were restricted to only 24 most prevalent SITs. The database also contains a total of 2379 MIRU patterns (from 8161 clinical isolates) from 87 countries of patient origin (35 countries of isolation); these were grouped in 847 shared-types or MIRU international types (MIT) containing 6626 isolates and 1533 orphan patterns. Lastly, data on 5-locus exact tandem repeats (ETRs) were available on 4626 isolates from 59 countries of patient origin (22 countries of isolation); a total of 458 different VNTR patterns were observed - split into 245 shared-types or VNTR International Types (VIT) containing 4413 isolates) and 213 orphan patterns. Datamining of SITVITWEB further allowed to update rules defining MTC genotypic lineages as well to have a new insight into MTC population structure and worldwide distribution at country, sub-regional and continental levels. At evolutionary level, the data compiled may be useful to distinguish the occasional convergent evolution of genotypes versus specific evolution of sublineages essentially influenced by adaptation to the host. This database is publicly available at: http://www.pasteur-guadeloupe.fr:8081/SITVIT_ONLINE.     

聚合酶链反应扩增指纹多态性快速分型技术在部队结核病分子流行病学研究中的应用

目的 探讨南方部队结核病的分子流行病学规律。方法 设计一对特异性IS6110外向性引物，应用聚合酶链反应(PCR)建立检测结核分支杆菌DNA指纹多态性的方法，分析结核分支杆菌DNA多态性与流行病学的关系。结果 共检测分析了154株结核分支杆菌DNA的指纹多态性。根据这些菌株的指纹多态性特征共分为8个类型，以Ⅰ型(36．4％)、Ⅱ型(31．8％)和Ⅲ型(21．4％)为主，其余各型均少于4％。以20—29岁和30—39岁组在这三型中所占比例最大，分别为31．8％和27．9％。驻城镇部队与驻乡村部队以及结核病患者有无卡介苗接种史，在这三型的分布差异无显著统计学意义(P＞0．05)。但初治与复治患者分离菌株的PCR扩增指纹类型的分布差异有显著统计学意义(P＜0．05)。所检测菌株是否具有耐药性，在这三型中的分布差异也有显著统计学意义(P＜0．05)。菌株耐药主要为单耐异烟肼和利福平，耐药菌株在Ⅰ、Ⅱ、Ⅲ型中所占比例分别是44．4％、29．6％和14．8％。结论 PCR扩增指纹多态性分型技术是一种简便、快速、敏感、特异和重复性好的分型方法，可用于结核病的分子流行病学研究。南方部队结核分支杆菌的传播以Ⅰ、Ⅱ、Ⅲ型为主，应加强此三型菌株流行的监控。     

中国西北部两省区结核分枝杆菌临床分离株Spoligotyping分型初步分析

目的初步了解新疆和甘肃结核分枝杆菌的基因型、主要流行型及其分布特点,比较两省区之间基因型分布。方法采用随机抽样的方法挑选新疆地区结核分枝杆菌临床分离株179株,甘肃地区结核分枝杆菌临床分离株176株,采用间隔寡核苷酸分型(Spoligotyping)技术对所收集的临床分离株进行分型研究,分析我国西北部相邻的两省区结核分枝杆菌的基因型分布、主要流行型及其地区特征。结果新疆地区菌株分为47个基因型,其中28个基因型为新的型别,新疆菌株中北京家族占68.72%(123/179),其次为T家族(6.70%,12/179),H家族(3.91%,7/179)和CAS家族(2.23%,4/179);甘肃地区菌株分为29种基因型,其中10个基因型为新的型别,甘肃菌株中北京家族占86.93%(153/176),其次为T家族(4.55%,8/176),H家族(1.14%,2/176),MANU2(1.14%,2/176)和CAS(0.57%,1/176)。结论北京基因型菌株在新疆和甘肃地区均为主要流行株,但甘肃地区北京基因型菌株比例明显高于新疆地区。     

The Li-Fraumeni syndrome: from clinical epidemiology to molecular genetics.

The goal of this review is to demonstrate the effective interaction of epidemiologic methods and molecular genetics in the identification of familial cancer predisposition. The example involves a hospital-based population of childhood soft tissue sarcoma patients who were less than age 16 years at diagnosis at the University of Texas M. D. Anderson Cancer Center, Houston, Texas, in 1944 through 1976, had survived at least 3 years from diagnosis, and were diagnosed at least 5 years before the start of our study. Familial data were collected on the patients' offspring, full siblings, parents, aunts, uncles, and grandparents. The initial analysis revealed a small but significant cancer excess in first-degree relatives. Genetic analysis demonstrated that the cancer distribution in families could best be explained by a rare autosomal dominant gene with penetrance such that the risk of cancer by age 35 years was nearly 50%. Most of the evidence for a dominant gene came from nine kindreds. Laboratory investigation of fibroblasts from those kindreds provided an in vitro model of cellular immortalization and carcinogenesis. Germline mutations in the tumor suppressor gene p53 were found in two of the families, and studies are ongoing in the other kindreds. This review demonstrates the power of genetic epidemiologic methods to characterize statistically a cancer-predisposing gene and the application of molecular genetics to define the genetic defect.     

Current trends of Mycobacterium tuberculosis molecular epidemiology in Saudi Arabia and associated demographical factors

Data are scarce on demographical factors related to the population structure of Mycobacterium tuberculosis in Saudi Arabia. A study was conducted on 902 clinical isolates to explore current trends in the phylogeography and associated demographical factors of tuberculosis by using spoligotyping and 24 loci based MIRU-VNTR typing. Young male patients (aged 16–29 and 30–44) were predominant in this cohort. The phylogenetic diversity among M. tuberculosis isolates was found high, as almost all known genetic lineages were identified. Delhi/CAS (26.4%), EAI (13.7%) and Haarlem (11.3%) were the most common lineages observed, particularly among the low age groups (16–29 and 30–44 years), whereas elderly patients (>60 years) showed a predominance in the lineages S, Ghana, TUR and Uganda-I. A statistically significant association was observed between gender of the patients and lineages of EAI (p value 0.026) and LAM (p value 0.005). Overall, molecular strain cluster rate was 34.4% with an elevated rate among patients aged below 15 years (43.1%), while cases among the elderly (>60 years) showed the lowest degree of clustering (12.5%). The largest level of clustering was noticed among cases caused by strains of the lineages Haarlem (59.8%), Beijing (55.8%) and LAM (42.8%). The current population structure of M. tuberculosis in Saudi Arabia is highly diverse with significant associations to demography, transmission dynamics and origin of the patients. The difference in genotype distributions among low and high aged patients reflects the ongoing change in the strain population structure in the country.     

Molecular epidemiology and genetic diversity of Mycobacterium tuberculosis complex in the Cross River State,Nigeria

This study provides with a first insight on Mycobacterium tuberculosis complex epidemiology and genetic diversity in the Cross River State, Nigeria. Starting with 137 smear positive patients recruited over a period of 12 months (June 2008 to May 2009), we obtained 97 pure mycobacterial isolates out of which 81 (83.5%) were identified as M. tuberculosis complex. Genotyping revealed a total of 27 spoligotypes patterns with 10 clusters (n = 64% or 79% of clustered isolates, 2–32 isolates/cluster), with patients in the age group range 25–34 years being significantly associated with shared-type pattern SIT61 (p = 0.019). Comparison with SITVIT2 database showed that with the exception of a single cluster (SIT727/H1), all other clusters observed were representative of West Africa; the two main lineages involved were LAM10-CAM (n = 42/81% or 51.8%) of M. tuberculosis and AFRI_2 sublineage of Mycobacterium africanum (n = 27/81% or 33.3%). Subsequent 12-loci MIRU typing resulted in a total of 13 SIT/MIT clusters (n = 52 isolates, 2–9 isolates per cluster), with a resulting recent n ? 1 transmission rate of 48.1%. Available drug-susceptibility testing (DST) results for 58/81 clinical isolates revealed 6/58% or 10.4% cases of multiple drug-resistance (MDR); 5/6 MDR cases were caused by strains belonging to LAM10-CAM lineage (a specific cluster SIT61/MIT266 in 4/6 cases, and an orphan spoligotype pattern in 1/6 case). Additionally, MIT266 was associated with streptomycin resistance (p = 0.016). All the six MDRTB isolates were concomitantly resistance to streptomycin and ethambutol; however, 4/6 MDR strains with identical MIRU patterns were characterized by consecutive strain numbers hence the possibility of laboratory cross contamination could not be excluded in 3/4 serial cases. The present preliminary study underlines the usefulness of spoligotyping and 12-loci MIRU–VNTRs to establish a baseline of circulating genotypic lineages of M. tuberculosis complex in Nigeria.     

Molecular epidemiology of bovine tuberculosis. I. Mycobacterium bovis genotyping

The lack of a typing system for Mycobacterium bovis has, until recently, been an impediment to undertaking sophisticated epidemiological studies to assist in the control and eradication of tuberculosis in domestic animals. Molecular biology techniques for mycobacteria have been in development since the mid-1980s, leading to the availability of a number of genetic typing systems for M. bovis. The authors summarise the available techniques, identify those which are most useful at present and those which might prove useful in the future. The present recommendation is to use spoligotyping analysis for rapid, large scale screening of M. bovis isolates, and to use restriction fragment length polymorphism analysis using the polymorphic guanine and cytosine-rich repeat sequences probe where greater differentiation of isolates is required. In the future, systematic analysis of the genome sequence of M. bovis will allow the development of improved techniques that combine good discrimination with ease of use.     

MIRU-VNTR和Spoligotyping用于重庆地区210株儿童结核分枝杆菌临床分离株的基因分型

目的 评价间隔区寡核苷酸分型(Spoligotyping)和基于结核分枝杆菌散在分布数目可变串联重复序列分析(MIRU-VNTR)方法在重庆地区儿童结核病分子流行病学中的应用.方法 收集重庆地区210株儿童结核分枝杆菌(MTB)临床分离株,应用上述两种分型方法进行比较分析.结果 采用Spoligotyping分型方法,210株菌可分为2个基因群44种基因型,其中最大的1个基因群即北京家族(北京基因型)含有130株菌(61.90%).采用MIRU-VNTR分析发现24个位点的多态性差异较大,不同MIRU位点组合(12、15和24位点)的分辨率指数依次升高,后两个组合的差异是由位点ETR-B引起.各位点和各位点组合在北京家族菌株中的分辨率指数均高于非北京家族菌株.结论 重庆地区儿童MTB具有明显的基因多态性,其主要流行型为北京家族.在结核病原学监测中,可先采用Spoligotyping,再对成簇菌株进行15位点与ETR-B组合二次分型的联合分型策略,可提高分子流行病学调查效果.

Abstract：

Objective To evaluate the application of spacer oligonucleotide typing (Spoligotyping) and mycobaeterial interspersed repetitive unit-variable-number tandem repeat (MIRU-VNTR) analysis in the molecular-epidemiological study of tuberculosis and to discuss the characteristics of pediatric Mycobacterium (M.) tuberculosis strains in Chongqing. Methods M. tuberculosis strains isolated and typed by Spoligotyping and MIRU-VNTR respectively, from the children patients in Chongqing and to compare the results from both methods, epidemiologically. Results By means of Spoligotyping, 210 clinical isolates were divided into 2 gene groups, displaying 44 genotypes. Among them, the biggest group was M. tuberculosis Beijing family, including 130 strains (61.90%) ,using the Spoligotyping. From the results of MIRU-VNTR, 24 loci showed different polymorphism and the HGI of different loci set (12 old loci, 15 basic loci and 24-loci set) increased accordingly. The subtle difference in HGI was originated from one locus ETR-B, which was included in the 24-locus system. The diversity of each loci and MIRU-VNTR set for non-Beijing genotype strains was higher than that of the Beijing genotype strains. Conclusion In this study, it was preliminarily confirmed the existence of high polymorphism of M. tuberculosis while the Beijing Family was the main genotype and main prevalent strain in children of Chongqing area. Spoligotyping prior to 15-locus with ETR-B combination seemed more suitable for the massive epidemiological investigation of pediatric tuberculosis patients.