三种不同的DNA分型技术在158株结核杆菌研究中的应用

目的评价IS6110限制性片段长度多态性(RFLP)、间隔区寡核苷酸分型(Spoligotyping)及分枝杆菌散在重复单位(MIRU)三种分型方法在结核病流行病学研究中的应用。方法对158株结核分枝杆菌临床分离株应用IS6110RFLP、Spoligotyping及MIRU三种分型方法进行鉴定。结果应用三种分型方法产生的类型数分别为118、20和105个。IS6110RFLP的分辨率大于Spoligotyping,MIRU的分辨能力与IS6110RFLP接近。在MIRU的12个区中,重复区4、10、26、40具有较高的多态性。广东地区与其他地区成簇率和北京基因型所占比例差异有统计学意义(P<0.05),广东地区成簇率和北京基因型所占比例均显著低于其他地区。结论应用IS6110RFLP、Spoligotyping及MIRU三种分型方法进行结核病流行病学研究具有重要意义且非常有效,可以发现中国不同地区菌株的不同特点。     

24-locus MIRU-VNTR and Spoligotyping analysis of drug-resistant Mycobacterium tuberculosis strains isolated from Northeastern Thailand

Tuberculosis, caused by Mycobacterium tuberculosis (MTB) infection, remains a global health problem with increased concerns due to drug-resistant tuberculosis. However, molecular genotyping profiles may give insight of the transmission of TB in a particular region. The present study aimed to characterize the genetic diversity of drug-resistant MTB and evaluate primer sets applied for the epidemiological study of circulating MTB in Northeastern Thailand. A total of 92 MTB isolates, resistant to rifampicin and/or isoniazid, were collected from the Office of Disease Prevention and Control between 2013 and 2016. All isolates were genotyped by 24-locus MIRU-VNTR typing combined with spoligotyping. We also analyzed the distributions of drug susceptibility pattern and demographic data among different genotypes. In comparison with different loci sets, discriminatory power based on 12, 15, 24 standard primers were investigated. Eighty-six particular profiles were found; among the patterns, two clusters were produced in 8 strains. East African Indians (EAI) were the most prevalent strains (33 isolates, 35.87%) followed by Beijing (30 isolates, 32.61%), with 23 unknown isolates strains also found. The HGDI based on combination of 24 loci analysis and spoligotyping was 0.9962. The number of tandem repeat generated was highly discriminant (HGDI>0.6) at locus 580 (0.66), 960 (0.67), 2163b (0.73), 2165 (0.62), 2461 (0.68) 3690 (0.73) and 4052 (0.79), respectively. In contrast, the diversity at locus 154 and 2059 was not revealed. The results emphasized that 24-locus MIRU-VNTR and spoligotyping could be useful for epidemiological surveillance of drug-resistant MTB in this region. At a given allelic diversity, 7 primer sets containing MIRU04, MIRU10, QUB2163b, ETRA, ETRB, Mtub39 and QUB26 may be considered for screening the VNTR patterns. In addition, this study gathered both demographics and genotypic data within the same investigation for further tuberculosis prevention and control.     

Spoligotypes of Mycobacterium tuberculosis isolates of a high tuberculosis burden aboriginal township in Taiwan

To understand the genotype of Mycobacterium tuberculosis isolates circulating in the aboriginal Sioulin Township, the highest tuberculosis (TB) endemic area in Taiwan, a total of 138 isolates were collected between January 2003 and December 2004 for genotyping. Genotyping consisted of spacer oligonucleotide typing (spoligotyping), IS6110-restriction fragment length polymorphism (RFLP) and mgtC and ogt single nucleotide polymorphisms (SNPs) characterizations. Spoligotyping data were compared with those from the fourth international spoligotyping database, SpolDB4. Of 27 resolved spoligotypes, 14 spoligotype patterns matched those found in SpolDB4 and 13 (TW1–13) were identified as novel. The most common among the 14 defined spoligotypes was Beijing ST1 (35.5%, 49/138), followed by Haarlem ST742 (10.9%, 15/138), Latin-American-Mediterranean (LAM) ST33 (5.8%, 8/138) and Haarlem ST50 (3.6%, 5/138). Of the 13 novel spoligotypes, 5 (TW 6–8, 12 and 13) were identified as “Haarlem-like” lineages according to clade analyses of spoligotyping and RFLP dendrograms. Overall, major spoligotypes found in Sioulin Township were Haarlem and Haarlem-like (39.1%), Beijing (38.4%), and LAM (5.8%) lineages. Interestingly, the results did not indicate any East-African-Indian lineages, which are highly prevalent in Far-East Asia. Our data also contained the first evidence of ST33 (LAM3 lineage) in Asia. This study provides first depiction of molecular epidemiology of M. tuberculosis in this isolated aboriginal population and further elucidation of the global historical expansion of the isolates.     

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.     

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 and drug susceptibility of Mycobacterium tuberculosis isolates from Chongqing Municipality,China

China’s tuberculosis (TB) burden is second only to that of India worldwide. In Chongqing, the largest municipality in southwestern China, although the prevalence of both TB and drug-resistant TB is higher than in other municipalities, the molecular characteristics and drug susceptibility phenotypes are poorly known. In this study, 297 Mycobacterium tuberculosis isolates from Chongqing were genotyped with spacer oligonucleotide typing (spoligotyping) and 28-locus MIRU-VNTR (24-locus MIRU-VNTR scheme and 4 other loci). Spoligotyping results were compared with drug-resistant profiles. Patients who showed clustering by both spoligotyping and 28-locus MIRU-VNTR were interviewed to investigate their detailed contact history. Our data demonstrated that the Beijing genotype was the most prevalent genotype, and ST1 was the most predominant lineage in Chongqing. The Beijing genotype was significantly associated with ethambutol resistance and multidrug-resistant phenotypes. A combination of the 10 most polymorphic loci permitted to achieve higher discriminatory power than 24-VNTR. In addition, a presumed transmission pathway was observed in a cluster of patients with the same MIRU-VNTR profile. The 10-VNTR locus set is suitable for genotyping of Mycobacterium tuberculosis in Chongqing.     

河南省结核菌分离株26位点MIRU-VNTR和Spoligotyping分子分型及耐药分析

目的 探讨河南省结核杆菌的遗传多样性。方法 使用26位点（经典24位点和其他2位点）的分支杆菌散在重复单元中数目可变串联重复序列（mycobacterium interspersed repetitive unit-variable number tandem repeat,MIRU-VNTR）和间隔区寡核苷酸分型（spoligotyping）对来自2015年期间河南省不同地区的668株结核杆菌分离株进行分型分析。对结核菌spoligotype类型和耐药表型的相关性进行分析。结果 Spoligotyping分析表明668株结核杆菌被分到10个不同的基因簇中。北京家族基因型是河南地区结核杆菌中的优势菌株。北京家族基因型菌株对四种一线药全耐药以及耐多药菌株比例明显高于非北京型菌株。668株结核杆菌通过26位点VNTR被分为567个不同的基因型。26个位点中15个位点具有高度或适中的分辨能力。10个分辨能力最强位点的组合分辨力能与26位点相当。结论 北京家族是河南省最流行的结核杆菌基因型。10位点VNTR和spoligotyping相结合可有效地用于河南省结核杆菌进化遗传学研究。     

Characterization of predominant Mycobacterium tuberculosis strains from different subpopulations of India

The predominant strains from India belong to Central-Asian (CAS) and the East-African-Indian (EAI) clade of Mycobacterium tuberculosis. The two clades have also been shown to be geographically partitioned. The study of such strains may help to understand the characteristics that make M. tuberculosis an effective pathogen and its overrepresentation in certain populations. M. tuberculosis isolates characterized by spoligotyping under a population based tuberculosis study covering different regions from the North and South India were further analyzed by restriction fragment length polymorphism (RFLP) and by deletion analysis of M. tuberculosis specific deletion region 1 (TbD1). The genetic relationship of the two clades inferred using different genetic markers showed good correlation. In the North where the CAS clade predominates the isolates are characterized by presence of high IS6110 copy number and absence of TbD1 region whereas in the South where the EAI clade predominates the isolates are characterized by low copy number of IS6110 and presence of TbD1 region. The ancestral EAI strains were found to be less often associated with drug resistance or young age as compared to the CAS clade. The study highlights that the EAI lineage is well established in India and that CAS may be emerging or more recently introduced to India. The results depict a distinction in the lineage of strains from the North versus South India indicating a need to study if the pathogen has adapted to specific human populations.     

Efficient Differentiation of <Emphasis Type="Italic">Mycobacterium tuberculosis</Emphasis> Strains of the W-Beijing Family from Russia using Highly Polymorphic VNTR Loci

The W-Beijing family is a widespread Mycobacterium tuberculosis clonal lineage that frequently causes epidemic outbreaks. This family is genetically homogeneous and conserved, so ETR-VNTR (exact tandem repeat-variable number of tandem repeats) typing is insufficient for strain differentiation, due to a common ETR-A to E profile (42435). This leads to the false clustering in molecular epidemiological studies, especially in the regions of predominance of the W-Beijing family. In this study, we searched for VNTR loci with a high evolutionary rate of polymorphism in the W-Beijing genome. Here we further evaluated VNTR typing on a set of 99 Mycobacterium tuberculosis clinical isolates and reference strains. These isolates were characterized and classified into several genotype families based on three ETR loci (A, C, E) and eight additional loci [previously described as QUB (Queen’s University Belfast) or MIRU (Mycobacterial Interspersed Repetitive Units) or Mtubs]. Ninety-nine strains were divided into 74 VNTR-types, 51 isolates of the W-Beijing family identified by IS6110 RFLP-typing (the restriction fragment length polymorphism-typing) and/or spoligotyping were subdivided into 30 VNTR-types. HGDI (the Hunter–Gaston discriminatory index) for all studied loci was close to that of IS6110 RFLP typing, a “gold standard” method for subtyping M. tuberculosis complex strains. The QUB 26 and QUB 18 loci located in the PPE genes were highly polymorphic and more discriminative than other loci (HGDI is 0.8). Statistically significant increase of tandem repeats number in loci ETR-A, -E, QUB 26, QUB 18, QUB 11B, Mtub21 was revealed in the W-Beijing group compared to genetically divergent non-W-Beijing strains. Thirty-six isolates were subjected to IS6110 RFLP typing. The congruence between results of the IS6110 RFLP typing and 11-loci VNTR typing was estimated on 23 isolates of the W-Beijing family. These isolates were subdivided into 9 IS6110-RFLP types and 13 VNTR types. The poor profiles correlation (0.767) reflects the differences in the rate and type of evolution between genome regions targeted by IS6110-RFLP and VNTR typing. VNTR typing in proposed format is powerful tool for discrimination of M. tuberculosis strains with different level of genetic relationship.     

厦门市临床分离的466株结核分枝杆菌基因分型研究

目的 了解厦门市结核分枝杆菌基因类型分布及主要流行基因群情况,并建立分型数据库。方法 采用实时荧光PCR法对厦门市2013 - 2015年分离到的466株结核分枝杆菌临床分离株进行菌株确认,然后采用间隔区寡核苷酸分型方法（spoligotyping）对其进行基因分型。分型结果与SpolDB4数据库进行比对,并使用Bionumeric6.6.4软件进行基因聚类分析。结果 466株菌均为结核分枝杆菌,基因分型分成96种基因型别,62种数据库中有相应的SIT编号,34种为新的型别。97.64%(455/466)的菌构成了15个基因簇。466株菌属于7个基因家族及未定义家族,排在前三的分别为:Beijing（北京）家族60.09%（280/466）、T家族21.03%(98/466)、H家族5.58%(26/466)。结论 厦门市结核分枝杆菌基因型别呈现多样性,北京家族为主要的流行基因群。     

Spoligotyping and Mycobacterium tuberculosis

We evaluated the clinical usefulness of spoligotyping, a polymerase chain reaction-based method for simultaneous detection and typing of Mycobacterium tuberculosis strains, with acid-fast bacilli-positive slides from clinical specimens or mycobacterial cultures. Overall sensitivity and specificity were 97% and 95% for the detection of M. tuberculosis and 98% and 96% when used with clinical specimens. Laboratory turnaround time of spoligotyping was less than that for culture identification by a median of 20 days. In comparison with IS6110-based restriction fragment length polymorphism typing, spoligotyping overestimated the number of isolates with identical DNA fingerprints by approximately 50%, but showed a 100% negative predictive value. Spoligotyping resulted in the modification of ongoing antimycobacterial treatment in 40 cases and appropriate therapy in the absence of cultures in 11 cases. The rapidity of this method in detection and typing could make it useful in the management of tuberculosis in a clinical setting.     

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.     

Associations of Mycobacterium tuberculosis genotypes with different ethnic and migratory populations in Taiwan

The distribution of human Mycobacterium tuberculosis (MTB) genotypes is reportedly associated with geography, ethnicity and population migrations. Three groups of 208 patients with tuberculosis in Taiwan were sampled to test this observation: (1) 41 aborigines of Austronesian ethnicity, who have been inhabiting in Taiwan for more than 500 years; (2) 58 veterans of Han Chinese origin, who moved as the first generation from Mainland China to Taiwan 55-60 years ago; and (3) 109 patients representing the general Taiwanese population of Han Chinese whose ancestors migrated to Taiwan around 200-400 years ago. A total of 208 MTB isolates, one per patient, were analyzed by spoligotyping and mycobacterial interspersed repetitive unit (MIRU) typing. Beijing ancient strains and Haarlem strains predominated among aborigines, while Beijing modern strains were common among veterans and the general population. All Beijing strains were further analyzed by typing the NTF loci and RD deletion. Results suggest a chronological trend among Beijing isolates from the three groups: isolates from the aborigines had signatures compatible with ancient lineages, and those from veterans and the general population were more contemporary. Our data indicate that the distribution of MTB genotypes/strains in Taiwan is associated with different populations whose migratory activities occurred between 55 and 500 years ago. These results suggest that transmission of MTB may have been relatively restricted to close contacts.     

Multidrug-resistant tuberculosis in prison inmates, Azerbaijan.

In a tuberculosis (TB) program in the Central Penitentiary Hospital of Azerbaijan, we analyzed 65 isolates of Mycobacterium tuberculosis by IS6110-based restriction fragment-length polymorphism (RFLP) and spoligotyping. From 11 clusters associated with 33 patients, 31 isolates had an IS6110-based banding pattern characteristic of the Beijing genotype of M. tuberculosis. In addition, 15 M. tuberculosis isolates with similar RFLP patterns constituted a single group by spoligotyping, matching the Beijing genotype. Multidrug resistance, always involving isoniazid and rifampin, was seen in 34 (52.3%) of 65 isolates, with 28 belonging to the Beijing genotype.     

河南省结核分枝杆菌IS6110DNA指纹图谱特征分析

目的：从分子流行病学角度探讨河南省结核分支杆菌的分布特征。方法：样本的获得采用全省范围等比例分层整群随机抽样;构建以IS6110 RFLPDNA指纹方法和以DR为基础的Spoligotyping DNA指纹方法;采用Gel compare4．1软件对DNA指纹图谱进行聚类（cluster）分析。结果：共获得66株可进行IS6110 RFLP DNA指纹分析的结核分支杆菌;其中59．09％（39／66）用Spoligotyping DNA指纹方法鉴定为“北京基因型”菌株。结论：北京基因型结核分支杆菌在河南省呈较高水平的流行。     

Role of spoligotyping and IS6110-RFLP in assessing genetic diversity of Mycobacterium tuberculosis in India

In the present study, genetic diversity analysis of Mycobacterium tuberculosis isolated from patients attending a tertiary care hospital, North India, has been attempted. Eighty three isolates of M. tuberculosis were subjected to DNA fingerprinting using spoligotyping and IS6110-RFLP techniques. Spoligotype patterns showed that central Asian (32.5%), ill defined T (13.2%) and Beijing (10.8%) families were predominant in ongoing transmission of the bacterium. Two STs; ST26 (CAS_Delhi) and ST1 (Beijing) represented 36.1% of the total M. tuberculosis population in eastern Uttar Pradesh, North India. IS6110 RFLP analysis showed that isolates having low and zero copy number of the IS element were 15.6% and 19.2%, respectively. Out of the 47 isolates clustered by spoligotyping, 40 could be further differentiated as unique strains by IS6110-RFLP. Therefore, this study recommends that both the techniques be used simultaneously for DNA fingerprinting of M. tuberculosis in India.     

First case of multidrug-resistant tuberculosis caused by a rare “Beijing-like” genotype of Mycobacterium tuberculosis in Bogotá, Colombia

This report describes a first case due to a genetically distinct and relatively rare “Beijing-like” strain of Mycobacterium tuberculosis isolated from a 15 years old female patient who died shortly after the initiation of antituberculous therapy with second-line drugs. Positive cultures obtained from lung, kidney and adrenal glands upon autopsy were identified as Mycobacterium tuberculosis complex characterized by an identical 15-banded IS6110-RFLP pattern, and were found to be resistant to all the 4 first-line antituberculous drugs tested (rifampin, isoniazid, ethambutol and streptomycin). Spoligotyping followed by comparison with the SITVIT2 database revealed that the isolate belonged to a rare pattern identified as Spoligotype International Type SIT190, which represents only 1.7% of all the Beijing strains worldwide. We present data on its worldwide distribution and present an evolutionary scenario based on available MIRU typing data.     

70株浙江省结核分枝杆菌临床分离株Spoligotyping基因分型研究

目的了解结核分枝杆菌临床分离株相关基因型的分布情况，并分析北京家族菌株与耐药的相关性。方法收集浙江省结核分枝杆菌临床分离株，常规罗氏培养基培养，应用Spoligotyping进行基因分型研究，聚类分析采用BioNumerics软件，统计学分析采用卡方检验。结果70株浙江省结核分枝杆菌临床分离株可分为2个基因群，即北京家族（Beijing family）和非北京家族（Non-Beijing family），分别占70％（49／70）和30％（21／70），18种基因型，其中12株为独特类型，剩余58株分为6簇。北京家族菌株中，89．8％（44／49）为典型北京家族（typical Beijing family），非北京家族菌株表现为高度的基因多态性，可分为13个基因型，9株为独特的基因型。北京家族菌株中表现为全敏感者71．4％（35／49），表现为耐药者为28．6％（14／49）；而非北京家族菌株中表现为全敏感者为66．7％，表现为耐药者为33．3％，经卡方检验，两者问的差异无统计学意义（X^2=0．158，P〉0．05）。结论北京家族菌株为浙江的流行优势菌株。北京基因犁与耐药无明显相关性。     

Genetic diversity of multidrug-resistant Mycobacterium tuberculosis isolates in Punjab,Pakistan

Pakistan ranks 5th among the world's highest tuberculosis (TB) burden countries and 6th among the countries with the highest prevalence of drug-resistant TB. However, insufficient data are available on the genetic structure of M. tuberculosis strains circulating in this country. The objective of this study was to explore the genetic diversity of multidrug-resistant M. tuberculosis isolates from Punjab, Pakistan with a combination of spoligotyping and 24-loci MIRU-VNTR typing.Among a total of 127 MDR isolates studies, 53 spoligotypes were obtained, split into 14 clusters (n = 88, 69.3%, 2–29 isolates per cluster) and 39 (30.7%) unique patterns. At the phylogenetic level, the most prevalent sublineage was CAS1_DELHI (n = 53, 41.7%), mostly represented by ST 1942 (n = 29, 22.8%), followed by T1 (n = 14, 11%) and Beijing (n = 10, 7.8%). The remaining nine sublineages (CAS, MANU2, EAI5, T2, LAM10_CAM, H1, X1, H4 and CAS2) involved altogether 24 (18.9%) isolates. Twenty-six (20.5%) isolates could not be assigned to any specific clade. MIRU-VNTR typing identified 123 (96.8%), 97 (76.4%) and 65 (51.2%) unique types with a tolerance of 0, 1, and 2 locus differences between the patterns.Upon combined spoligotyping and MIRU-VNTR typing analysis, 123 (96.8%), 108 (85%), and 91 (71.7%) unique types were identified if a tolerance of 0, 1, and 2 locus differences in the MIRU-VNTR patterns was assumed, respectively. Based on the clustering results, the transmission rate for MDR-TB cases under the study was calculated at 3.2%, 15%, and 28.3%.Overall, three clades, namely CAS1_DELHI, T1, and Beijing accounted for the majority of MDR-TB cases in Pakistan. Up to a third of the cases were clustered upon combined spoligotyping and MIRU-VNTR typing, suggesting a moderate level of active transmission.