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。     

The population structure of drug-resistant Mycobacterium tuberculosis clinical isolates from Sichuan in China

China ranks second next to India among 22 high-burden countries despite decades' effort on tuberculosis (TB) control. The Sichuan province today contains the second-largest number of TB cases among Chinese provinces, where the prevalence of drug-resistant TB, especially MDR-TB, is much higher than the average level in eastern China. In this study, the population structure and the transmission characteristics of drug-resistant TB in Sichuan province were studied by spoligotyping and 24-locus Mycobacterial interspersed repetitive units-variable number tandem DNA repeats (MIRU-VNTR), applied to a total of 306 clinical isolates. Spoligotyping-based analysis showed that Beijing family represented 69.28% of all isolates and constituted the largest group (66.24%) of MDR-TB in Sichuan. The remaining isolates, accounting for 33.76% of MDR isolates, belonged to the ill-defined T family, Manu2, H3, LAM9, and other minor unassigned clades. The discriminatory power evaluated for spoligotyping was poor (HGI=0.595), but high for 24-locus MIRU-VNTRs (HGI=0.999). The number of the most discriminatory loci (h>0.6) was 12, including locus 424, 802, 960, 1644, 1955, 2163b, 2996, 3007, 3192, 3690, 4348 and 4052. It was concluded that 24-locus MIRU-VNTRs could be a more discriminatory tool for differentiating clinical isolates from Sichuan region. The small clustering size obtained from the current population structure analysis suggested that the high prevalence of drug-resistant TB in this region might be attributed partially to the acquired resistance due to inappropriate drug use rather than active transmission of drug-resistant TB (primary resistance).     

Molecular snapshot of drug-resistant and drug-susceptible Mycobacterium tuberculosis strains circulating in Bulgaria

We report results of the first study on the molecular basis of drug resistance in Mycobacterium tuberculosis strains currently circulating in Bulgaria. The study panel consisted of 133 (including 37 drug-resistant) isolates recovered from newly diagnosed, adult pulmonary TB patients from different regions of Bulgaria in 2005-2006. Three types of the rpoB mutations were found in 20 of 27 RIF-resistant isolates; rpoB S531L was the most frequent. Eleven (48%) of 23 INH-resistant isolates had katG S315T mutation. inhA -15C>T mutation was detected in one INH-resistant isolate (that also had katG315 mutation) and three INH-susceptible isolates. A mutation in embB306 was found in 7 of 11 EMB-resistant isolates. Comparison with spoligotyping and 24-VNTR locus typing data suggested that emergence and spread of drug-resistant and MDR-TB in Bulgaria are not associated with any specific spoligotype or MIRU-VNTR genotype.     

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.     

Penitentiary population of Mycobacterium tuberculosis in Kyrgyzstan: Exceptionally high prevalence of the Beijing genotype and its Russia-specific subtype

Here, we present results of the first study of the Mycobacterium tuberculosis genotypes circulating in Kyrgyzstan. We focused on the incarcerated population known to be at high-risk for tuberculosis (TB) and with a significant impact on TB incidence in the general population. Beijing genotype was detected in 42 of 56 M. tuberculosis sputum-extracted DNA samples from newly-diagnosed adult pulmonary TB patients. RIF and INH resistance was genotypically detected in 28% and 55% samples; 13 of 15 MDR strains belonged to Beijing genotype. 12-locus MIRU-VNTR typing showed 8 of 56 samples to be mixed cases; 7 of them contained a Beijing strain. MIRU analysis demonstrated a high homogeneity of the studied collection (HGI = 0.66) while 28 of 56 strains had a profile 223325153533 corresponding to Beijing/M2 subtype highly prevalent in different Russian settings. Three hypervariable loci, QUB-3232, VNTR-3820 and VNTR-4120, permitted to further subdivide 28 Beijing/M2 strains into 11 subtypes shared by 1 to 9 strains. To conclude, all markers taken together, the penitentiary population of M. tuberculosis in Kyrgyzstan exhibited a strong genetic affinity to Russia and a weak relatedness to East Asia.     

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.     

Genotypic diversity of multidrug-, quinolone- and extensively drug-resistant Mycobacterium tuberculosis isolates in Thailand

Drug-resistant tuberculosis (TB), which includes multidrug-resistant (MDR-TB), quinolone-resistant (QR-TB) and extensively drug-resistant tuberculosis (XDR-TB), is a serious threat to TB control. We aimed to characterize the genotypic diversity of drug-resistant TB clinical isolates collected in Thailand to establish whether the emergence of drug-resistant TB is attributable to transmitted resistance or acquired resistance. We constructed the first molecular phylogeny of MDR-TB (n = 95), QR-TB (n = 69) and XDR-TB (n = 28) in Thailand based on spoligotyping and proposed 24-locus multilocus variable-number of tandem repeat analysis (MLVA). Clustering analysis was performed using the unweighted pair group method with arithmetic mean. Spoligotyping identified the Beijing strain (SIT1) as the most predominant genotype (n = 139; 72.4%). The discriminatory power of 0.9235 Hunter–Gaston Discriminatory Index (HGDI) with the 15-locus variable-number tandem repeats of mycobacterial interspersed repetitive units typing was improved to a 0.9574 HGDI with proposed 24-locus MLVA, thereby resulting in the subdivision of a large cluster of Beijing strains (SIT1) into 17 subclusters. We identified the spread of drug-resistant TB clones caused by three different MLVA types in the Beijing strain (SIT1) and a specific clone of XDR-TB caused by a rare genotype, the Manu-ancestor strain (SIT523). Overall, 49.5% of all isolates were clustered. These findings suggest that a remarkable transmission of drug-resistant TB occurred in Thailand. The remaining 50% of drug-resistant TB isolates were unique genotypes, which may have arisen from the individual acquisition of drug resistance. Our results suggest that transmitted and acquired resistance have played an equal role in the emergence of drug-resistant TB. Further characterization of whole genome sequences of clonal strains could help to elucidate the mycobacterial genetic factors relevant for drug resistance, transmissibility and virulence.     

不同可变数目串联重复序列组合对中国流行结核分枝杆菌分辨力的评价研究

目的 在规范化的结核分枝杆菌（Mycobacterium tuberculosis,MTB）可变数目串联重复序列（variable number of tandem repeats,VNTR）基因分型的基础上,构建我国31个省（自治区、直辖市）VNTR数据库,每个省优化一套VNTR位点组合,为我国结核病预防控制策略的制定提供科学依据。方法 对2007－2008年全国结核病耐药性基线调查的4 116株MTB15位点VNTR（15-VNTR）基因分型。汉高指数（Hunter-Gaston Index,HGI）分析每个位点的分辨率。依据谱系流行特征,以分辨率高和稳定性强为原则,为各省设计一套VNTR优化组合（12-VNTR、10-VNTR、8-VNTR和5-VNTR）,采用HGI和成簇率进行评价。结果 完成了涵盖率为96.36%（3 966/4 116）MTB完整15-VNTR图谱。发现QUB11b、MIRU26等7个高分辨率位点;QUB26、MIRU16、Mtub21、QUB11b在部分地区遗传稳定性差。内蒙古自治区、重庆市、黑龙江省的最优组合为10-VNTR,其他各省的最佳组合为8-VNTR。结论 VNTR数据库的建立将推动全国范围MTB传染源的追踪;各省优化VNTR组合的推出有助于当地结核病疫情的监测和群体遗传学的研究。     

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.     

Genotypes and genetic characters of Mycobacterium tuberculosis from Myanmar using three typing methods

Knowledge on basic characteristics of Mycobacterium tuberculosis (MTB) is helpful to understand the disease epidemiology and support the prediction of clinical outcome of the disease. The aim of this study was to detect the genotypes and genotypic characters of clinical Mycobacterium tuberculosis (MTB) isolates from new and retreatment rifampicin-resistant patients using three different genotyping methods. Mycobacterial interspersed repetitive units-variable number tandem repeat (MIRU-VNTR) typing was used to determine the diversity of 222 clinical isolates. Spoligotyping and IS6110-restriction fragment length polymorphism (RFLP) typing were also used to investigate the genetic characters of 105 MTB strains. Among the 15 genotypes detected by MIRU-VNTR, Beijing strains were the most prevalent of all strains (54.8%); new cases (40.5%) and retreatment cases (69.4%), followed by EAI strain. Spoligotyping categorized the strains into 11 lineages and 13 orphans whereas 96 different IS6110 patterns were identified using RFLP method. The mode number of IS6110 was 18 and 20. Higher band numbers were found in Beijing genotype (p < 0.001). Clustering rates by spoligotyping, MIRU-VNTR and IS6110-RFLP typing were 0.714, 0.004 and 0.085, respectively. Discriminatory powers of spoligotyping, MIRU-VNTR typing and IS6110-RFLP typing were 0.637, 1.000 and 0.997, respectively. Dominant Beijing genotype in both new and retreatment cases denoting that prevailing tuberculosis in Myanmar changed from EAI to Beijing lineage.     

Circulating strains of Mycobacterium tuberculosis: 24 loci MIRU-VNTR analysis in Bangladesh

Bangladesh is among the high burden countries for tuberculosis (TB) and multidrug resistant TB (MDR-TB). As the genetic diversity and distinct phylogeographic distribution of Mycobacterium tuberculosis are responsible for regional differences in drug resistance, this cross sectional study was conducted to identify the circulating M. tuberculosis strains belonging to different lineages among pulmonary tuberculosis and, to investigate the contribution of distinct M. tuberculosis lineages to rifampicin resistant (RR) and rifampicin sensitive (RS) TB. A total of 40 RR and 20 RS isolates were enrolled in this study, all of which confirmed as M. tuberculosis by MPT 64 antigen detection. Furthermore, all isolates were genotyped by 24 loci Mycobacterial Interspersed Repetitive Units-Variable Number of Tandem Repeats (MIRU-VNTR), thus comprising the first study to employ this approach in Bangladesh. Beijing was the predominant lineage (26.8%) followed by EAI (23.2%), Delhi/CAS (16.1%), H37Rv (8.9%), Haarlem (7.1%), LAM (5.4%), Cameroon (3.6%) and a NEW-1 (1.8%). Four (7.1%) isolates remained as unidentified. Beijing strains were the significantly predominant (36.8%; p = 0.0135) among the RR isolates in comparison with other strains whereas EAI was the predominant (38.8%) lineage among RS isolates. Also, approximately 13% RR isolates showed genotypic resistance against fluoroquinolones by LPA and, hence, classed as pre-XDR TB albeit no specific lineage was found associated with these latter strains. A low transmission rate (10.5%) and high genetic diversity was detected in this setting with all the clustered strains herein identified belonging to the Beijing lineage. This study highlights 24 loci MIRU-VNTR analysis as a powerful tool for genotyping of Mycobacterium tuberculosis in this setting as it shows a high discriminatory index (0.81).     

Genetic diversity and primary drug resistance transmission in Mycobacterium tuberculosis in southern Mexico

Tuberculosis is a global human health threat, especially in developing countries. The present study aimed to describe the genetic diversity of Mycobacterium tuberculosis and to measure the transmission rates of primary and acquired resistance. A total of 755 M. tuberculosis isolates from a cohort study of patients with culture-confirmed pulmonary tuberculosis in Orizaba, Veracruz, performed between 1995 and 2010 were genotyped by the 24-locus mycobacterial interspersed repetitive unit–variable number of tandem repeats (MIRU-VNTR) method. Drug susceptibility was determined. Logistic regression models were constructed to identify the variables associated with resistance and clusters. The recent transmission index (RTI), the Hunter-Gaston discrimination index (HGDI) for the MIRU-VNTR test and allelic diversity (h) were calculated. The Haarlem and LAM lineages were the most common in the population. A total of 519 isolates were grouped into 128 clusters. The overall drug resistance rate was 19%, isoniazid monoresistance (10%) was the most common, and 3.4% of the isolates were multidrug resistant. Among the 116 isolates resistant to at least one drug, the primary and acquired resistance rates were 81.9% and 18.1%, respectively. Primary resistance was associated with belonging to a cluster (aOR 4.05, 95% CI 1.5–11.2, p = 0.007). Previous treatment history (aOR 9.05, 95% CI 3.6–22.5, p < 0.001) and LAM lineage (aOR 4.25, 95% CI 1.4–12.7, p = 0.010) were associated with multidrug-resistant tuberculosis (MDR-TB). The RTI was 51.7%, and the 24-locus MIRU-VNTR HGDI was 0.98. The alleles with the greatest diversity were 4056-QUB26 (h = 0.84), 2163b-QUB11b (h = 0.79), and 424-Mtub04 (h = 0.72). Primary resistance transmission, high LAM lineage prevalence and its association with MDR-TB represent public health problems. The implementation of molecular tools is needed to improve the existing control surveillance tuberculosis program.     

Predominance of modern Mycobacterium tuberculosis strains and active transmission of Beijing sublineage in Jayapura,Indonesia Papua

Mycobacterium tuberculosis genotype distribution is different between West and Central Indonesia, but there are no data on the most Eastern part, Papua. We aimed to identify the predominant genotypes of M. tuberculosis responsible for tuberculosis in coastal Papua, their transmission, and the association with patient characteristics. A total of 199 M. tuberculosis isolates were collected. Spoligotyping was applied to describe the population structure of M. tuberculosis, lineage identification was performed using a combination of lineage-specific markers, and genotypic clusters were identified using a combination of 24-locus-MIRU-VNTR and spoligotyping. A high degree of genetic diversity was observed among isolates based on their spoligopatterns. Strains from modern lineage 4 made up almost half of strains (46.9%), being more abundant than the ancient lineage 1 (33.7%), and modern lineage 2 (19.4%). Thirty-five percent of strains belonged to genotypic clusters, especially strains in the Beijing genotype. Previous TB treatment and mutations associated with drug resistance were more common in patients infected with strains of the Beijing genotype. Papua shows a different distribution of M. tuberculosis genotypes compared to other parts of Indonesia. Clustering and drug resistance of modern strains recently introduced to Papua may contribute to the high tuberculosis burden in this region.     

Genotypes of Mycobacterium tuberculosis in patients at risk of drug resistance in Bolivia

Bolivia ranks among the 10 Latin American countries with the highest rates of tuberculosis (TB) and multidrug resistant (MDR) TB. In view of this, and of the lacking information on the population structure of Mycobacterium tuberculosis in the country, we explored genotype associations with drug resistance and clustering by analyzing isolates collected in 2010 from 100 consecutive TB patients at risk of drug resistance in seven of the nine departments in which Bolivia is divided. Fourteen isolates were MDR, 29 had other drug resistance profiles, and 57 were pansusceptible. Spoligotype family distribution was: Haarlem 39.4%, LAM 26.3%, T 22.2%, S 2.0%, X 1.0%, orphan 9.1%, with very low intra-family diversity and absence of Beijing genotypes. We found 66 different MIRU-VNTR patterns; the most frequent corresponded to Multiple Locus Variable Analysis (MLVA) MtbC15 patterns 860, 372 and 873. Twelve clusters, each with identical MIRU-VNTR and spoligotypes, gathered 35 patients. We found no association of genotype with drug resistant or MDR-TB. Clustering associated with SIT 50 and the H3 subfamily to which it belongs (p < 0.0001). The largest cluster involved isolates from three departments and displayed a genotype (SIT 50/MLVA 860) previously identified in Bolivian migrants into Spain and Argentina suggesting that this genotype is widespread among Bolivian patients. Our study presents a first overview of M. tuberculosis genotypes at risk of drug resistance circulating in Bolivia. However, results should be taken cautiously because the sample is small and includes a particular subset of M. tuberculosis population.     

Phylogenetic assignment of Mycobacterium tuberculosis Beijing clinical isolates in Japan by maximum a posteriori estimation

Intra-species phylogeny of Mycobacterium tuberculosis has been regarded as a clue to estimate its potential risk to develop drug-resistance and various epidemiological tendencies. Genotypic characterization of variable number of tandem repeats (VNTR), a standard tool to ascertain transmission routes, has been improving as a public health effort, but determining phylogenetic information from those efforts alone is difficult. We present a platform based on maximum a posteriori (MAP) estimation to estimate phylogenetic information for M. tuberculosis clinical isolates from individual profiles of VNTR types. This study used 1245 M. tuberculosis clinical isolates obtained throughout Japan for construction of an MAP estimation formula. Two MAP estimation formulae, classification of Beijing family and other lineages, and classification of five Beijing sublineages (ST11/26, STK, ST3, and ST25/19 belonging to the ancient Beijing subfamily and modern Beijing subfamily), were created based on 24 loci VNTR (24_Beijing-VNTR) profiles and phylogenetic information of the isolates. Recursive estimation based on the formulae showed high concordance with their authentic phylogeny by multi-locus sequence typing (MLST) of the isolates. The formulae might further support phylogenetic estimation of the Beijing lineage M. tuberculosis from the VNTR genotype with various geographic backgrounds. These results suggest that MAP estimation can function as a reliable probabilistic process to append phylogenetic information to VNTR genotypes of M. tuberculosis independently, which might improve the usage of genotyping data for control, understanding, prevention, and treatment of TB.     

Tuberculosis Disparity between US-born Blacks and Whites, Houston, Texas, USA

Tuberculosis (TB) rates in the United States are disproportionately high for certain ethnic minorities. Using univariate and multivariate analyses, we compared data for 1,318 US-born blacks with 565 US-born non-Hispanic whites who participated in the Houston TB Initiative (1995–2004). All available Mycobacterium tuberculosis isolates underwent susceptibility and genotype testing (insertion sequence 6110 restriction fragment length polymorphism, spoligotyping, and genetic grouping). TB in blacks was associated with younger age, inner city residence, HIV seropositivity, and drug resistance. TB cases clustered in 82% and 77% of blacks and whites, respectively (p = 0.46). Three clusters had >100 patients each, including 1 cluster with a predominance of blacks. Size of TB clusters was unexpectedly large, underscoring the ongoing transmission of TB in Houston, particularly among blacks.     

Genetic diversity among multidrug-resistant Mycobacterium tuberculosis strains in Mexico

Tuberculosis is an important public health problem in Mexico. However, limited information about the genetic diversity of Mycobacterium tuberculosis strains circulating in the country is available. In this work, 109 multidrug-resistant (MDR) M. tuberculosis isolates collected in 23 different states of Mexico in 2003 were retrospectively characterized by spoligotyping and MIRU-VNTRs. All isolates, except for a single cluster containing two strains (subcluster E1), were split when information from the 12-loci MIRUs and spoligo-pattern was simultaneously analyzed. The discriminative power of 12-loci MIRU-VNTR and spoligotyping, by the Hunter-Gaston index, were 0.9998 and 0.9011, respectively. These findings suggest that almost all cases were epidemiologically unrelated. Instead, the genetic variations observed among these strains are suggestive of emergence of acquired drug-resistance during the course of treatment. The results suggest a high degree of genetic variability and a high frequency of SIT53 (T1 family) spoligotype among the MDR M. tuberculosis isolates included in the study.     

Population-Based Geospatial and Molecular Epidemiologic Study of Tuberculosis Transmission Dynamics,Botswana, 2012–2016

Tuberculosis (TB) elimination requires interrupting transmission of Mycobacterium tuberculosis. We used a multidisciplinary approach to describe TB transmission in 2 sociodemographically distinct districts in Botswana (Kopanyo Study). During August 2012–March 2016, all patients who had TB were enrolled, their sputum samples were cultured, and M. tuberculosis isolates were genotyped by using 24-locus mycobacterial interspersed repetitive units–variable number of tandem repeats. Of 5,515 TB patients, 4,331 (79%) were enrolled. Annualized TB incidence varied by geography (range 66–1,140 TB patients/100,000 persons). A total of 1,796 patient isolates had valid genotyping results and residential geocoordinates; 780 (41%) patients were involved in a localized TB transmission event. Residence in areas with a high burden of TB, age <24 years, being a current smoker, and unemployment were factors associated with localized transmission events. Patients with known HIV-positive status had lower odds of being involved in localized transmission.