Prevalence of Haarlem I and Beijing types of Mycobacterium tuberculosis strains in Iranian and Afghan MDR-TB patients

Measuring the catastrophic cost of diagnosis, treatment, care, and support on people and families affected by tuberculosis in Iran and Afghanistan

Objectives

A key goal of the World Health Organization's End Tuberculosis (TB) Plan was to eliminate TB-related catastrophic costs by 2030. This study aimed to measure the achievement of two countries (Iran and Afghanistan) in this plan.

Design or Methods

Using a random cluster sampling, 649 patients with TB were interviewed in 2020. This study calculated the direct, indirect, and catastrophic costs for Iran and Afghanistan and applied regression estimators and a sensitivity analysis.

Results

The results showed that 49% of households in Afghanistan and 20% of households in Iran faced TB-related catastrophic costs. Being in multidrug-resistant treatment (odds ratio [OR] = 3.670) was related to facing catastrophic costs. Households with a female (OR = 0.532), being an Iran resident (OR = 0.429), and being a university degree-holder (OR = 0.284) patient with TB had a lower likelihood of facing catastrophic costs.

Conclusion

The findings of this study showed that these two countries are far from the goals of the World Health Organization for having zero TB-related catastrophic costs.

Prevalence and Temporal Trends of Multidrug-resistant Tuberculosis in Iran from 1981 to 2023: A Systematic Review and Meta-analysis

BACKGROUND

Multidrug-resistant tuberculosis (MDR-TB) is a serious threat to global tuberculosis (TB) control efforts. This study aims to investigate the trend of MDR-TB prevalence in Iran over 20 years.

METHODS

A systematic literature search was conducted in various databases, including PubMed, Embase, and Web of Science, from 1981 to 2023. Studies reporting the prevalence of MDR-TB in Iran were included in the meta-analysis. Statistical analysis was performed using Comprehensive Meta-Analysis software.

RESULTS

A total of 58 studies from different provinces of Iran were included in the meta-analysis. The majority of studies were from Tehran (n = 33), Kermanshah (n = 5), Mashhad (n = 4), and Tabriz (n = 4) provinces. Overall, 1885 cases of MDR-TB were reported in Iran during the study period. The highest number of MDR-TB cases was reported in 2000 (582 cases) and the lowest in 2001 (1 case). An increasing trend in MDR-TB prevalence was observed, particularly between 2018 and 2019. The pooled prevalence of MDR-TB in Iran was 12.31% (95% CI: 11.83-12.80) using the fixed-effects model and 20.21% (95% CI: 15.70-26.01) using the random-effects model. No evidence of publication bias was found.

CONCLUSION

The results of this comprehensive meta-analysis highlight the increasing trend of MDR-TB in Iran over the past two decades. This underscores the urgent need for strengthening TB control strategies, including improved surveillance, case detection, treatment, and management of MDR-TB in the country. Developing diagnostic and treatment approaches for MDR-TB should be prioritized by Iranian medical universities and public health authorities.

The occurrence rate of Haarlem and Beijing genotypes among Middle Eastern isolates of multi drug resistant Mycobacterium tuberculosis: A systematic review and meta-analysis

Antibiotic resistance is a serious problem that poses a major challenge to tuberculosis control worldwide. Many developing countries still struggle with this infection in term of various aspects as it remains a major health concern. A number of developing countries are located in the Middle East, one of the world's most important regions. The control of this infection remains largely suboptimal despite intensive research in the field, and the mechanisms that lead to its progression have not yet been fully understood. Therefore, TB control must be amended through the identification of new strategies. For this reason, monitoring genetic characterizations of TB strains by molecular typing methods in different geographical regions can be important to setting local programs and global strategies to control TB infection. It is important to know the genotype of Mycobacterium tuberculosis strains to evaluate the occurrence of outbreaks and the transmission of this disease. Beijing and Haarlem genotypes are the most prevalent and, in these families, there is greater association with drug resistance, resulting in more severe forms of TB and higher levels of treatment failure than in other families. The current study is planned to systematically conduct a review using a meta-analysis to show the prevalence of Beijing and Haarlem genotypes in the Middle Eastern MDR-TB cases. M. tuberculosis strains pose particular epidemiological and clinical concerns as they can endanger tuberculosis control programs.

Mycobacterium tuberculosis genotypes in an ethnically diverse area with millions of pilgrims and thousands of immigrants

BACKGROUND

Immigration is considered as a risk factor of tuberculosis (TB). Qom province receives millions of pilgrims and significant numbers of immigrants each year. Most of the immigrants to Qom, arrive from neighboring TB-endemic countries. This study aimed to identify the current circulating Mycobacterium tuberculosis genotypes in Qom province using 24-locus MIRU-VNTR genotyping.

METHODS

Eighty six M. tuberculosis isolates were collected during 2018-2022 from patients referring to Qom TB reference laboratory. The DNA of isolates was extracted and followed by 24 loci MIRU-VNTR genotyping which performed using the web tools available on MIRU-VNTRplus.

RESULTS

Of 86 isolates, 39 (45.3%) were of Delhi/CAS genotype, 24 (27.9%) of NEW-1, 6 (7%) of LAM, 6 (7%) of Beijing, 2 (2.3%) of UgandaII, 2 (2.3%) of EAI, 1 of S (1.2%) and 6 (7%) did not match with profiles present in MIRUVNTRplus database.

CONCLUSIONS

About half of the isolates belong to Afghan immigrants; which warns health policy makers about the future situation of TB in Qom. Also, the similarity of Afghan and Iranian genotypes provides evidence that immigrants partake in the circulation of M. tuberculosis. This study underpin the studies about the circulating M. tuberculosis genotypes, their geographical distribution, the association of TB risk factors with these genotypes and the impact of immigration on the situation of TB in Qom province.

Health condition of Afghan refugees residing in Iran in comparison to Germany: a systematic review of empirical studies

BACKGROUND

The re-emerging dominance of the Taliban in Afghanistan in 2021 caused a new wave of Afghan refugees heading Iran and neighboring countries. Iran in the Middle East and Germany in Europe are two major host countries to the largest populations of Afghan refugees. In both countries, several studies have been done to assess the health condition of refugees.

OBJECTIVES

To systematically review the existing literature to identify similarities and differences of health conditions of Afghan refugees living in the two countries, and to synthesize evidence on the health status and health care access of these populations.

METHODS

Related electronic databases and grey literature of Iran and Germany on the health of Afghan refugees were scanned and searched up for the period 2000-2020. Key terms were formed by combining "Afghan refugees or immigrants or populations or asylum seekers", "Physical or mental health", "Healthcare service or access or use", "Iran or Germany". Empirical studies were considered if they contained samples of Afghan refugees with particular outcomes for Afghans. Results were categorized for both countries in the three main areas of physical health, mental health, and access/use of healthcare services.

RESULTS

Nine hundred twenty-two documents were extracted, of which 75 full-texts were finally reviewed. 60 documents belonged to the health condition of Afghan refugees residing in Iran including 43 in physical health, 6 in mental health, 8 in healthcare access and use, and 3 in multiple aspects of health, and 15 belonged to Germany including 7 in physical health, 4 in mental health, 2 in healthcare access and use, and 2 in multiple aspects of health. A less explicit evaluation of the overall health condition of Afghan refugees was observable, particularly for Germany. While matches on the study subject exist for both countries, in comparison to Germany, we extracted more quantitative and qualitative health studies on Afghan refugees of the mentioned areas from Iran. German health studies were rare, less qualitative, and more on the health condition of diverse refugee groups in general.

CONCLUSIONS

Wide gaps and unanswered questions related to mental health and overall health status of the Afghan refugee population are observable, especially in Germany. Our systematic review identified the gap in evidence, which we would recommend to bridge using a wider lens to comprehensively assess the overall condition of refugees considering associations between health and socio-economic and cultural determinants instead of a one-dimensional approach. Further, within health studies on refugee populations, we recommend stratification of results by the country of origin to capture the within-group diversity among refugees with different countries of origin.

How Molecular Epidemiology Can Affect Tuberculosis Control in the Middle East Countries: A Systematic Review and Meta-Analysis

BACKGROUND

Nowadays, due to the incidence of specific strains of Mycobacterium tuberculosis and also an increase in the rate of drug resistant-TB, the mortality rate has been increased by this disease. The identification of common strains in the region, as well as the sources of transmission, is essential to control the disease, which is possible by using molecular epidemiology.

OBJECTIVES

In this survey, the studies utilizing the spoligotyping method in Muslim Middle East countries are reviewed to determine their role in the control of TB.

METHODS

All studies conducted from 2005 to June 2016 were considered systematically in three electronic databases out of which 23 studies were finally selected.

RESULTS

The average rate of clustering was 84% and the rate of recent transmission varied from 21.7% to 92.4%. The incidence of Beijing strains has been found to be rising in the abovementioned countries. In Iran and Saudi Arabia known as immigration and labour-hosting countries, respectively, rapid transmittable and drug-resistant Beijing strains were higher than those in other Muslim Middle East countries.

CONCLUSION

Considering the incidence of highly virulent strains, due to the increase in immigration and people infected with HIV, tuberculosis, especially drug-resistant form, careful monitoring is needed.

Beijing genotype of Mycobacterium tuberculosis is associated with extensively drug-resistant tuberculosis: A global analysis

We found that the frequency of Beijing genotype among XDR-TB strains was high. The data in this study would help guide the TB control program, and we however need further investigation to confirm the reliability of the present findings.

False-Positive Mycobacterium tuberculosis Detection: Ways to Prevent Cross-Contamination

The gold standard method for diagnosis of tuberculosis is the isolation of Mycobacterium tuberculosis through culture, but there is a probability of cross-contamination in simultaneous cultures of samples causing false-positives. This can result in delayed treatment of the underlying disease and drug side effects. In this paper, we reviewed studies on falsepositive cultures of M. tuberculosis. Rate of occurrence, effective factors, and extent of false-positives were analyzed. Ways to identify and reduce the false-positives and management of them are critical for all laboratories. In most cases, falsepositive is occurring in cases with only one positive culture but negative direct smear. The three most crucial factors in this regard are inappropriate technician function, contamination of reagents, and aerosol production. Thus, to reduce false-positives, good laboratory practice, as well as use of whole-genome sequencing or genotyping of all positive culture samples with a robust, extra pure method and rapid response, are essential for minimizing the rate of false-positives. Indeed, molecular approaches and epidemiological surveillance can provide a valuable tool besides culture to identify possible false positives.

Genetic diversity of Mycobacterium tuberculosis isolates causing pulmonary and extrapulmonary tuberculosis in the capital of Iran

OBJECTIVES

Evaluation of the genetic diversity of Mycobacterium tuberculosis (M.tb) and determining if the association between a specific genotype and the site of infection is crucial. Accordingly, the current study aimed at comparing predominant M.tb genotypes in pulmonary (PTB) and extrapulmonary tuberculosis (EPTB) isolates circulating in the capital of Iran.

METHODS

The genetic diversity of culture-confirmed PTB and EPTB isolates were evaluated by Spoligotyping and MIRU-VNTR (mycobacterial interspersed repetitive-unit-variable-number tandem-repeat) typing methods. Genotyping data were analyzed with SITVIT, MIRU-VNTRplus, and TBminer databases. To assess adjusted associations, chi-square/the Fisher exact test and multiple logistic regression model were applied.

RESULTS

URAL2 (NEW-1) (28/88; 31.8%) and CAS1-DELHI (25/84; 29.8%) genotypes were predominant in EPTB and PTB strains, respectively. Based on MIRU-VNTR typing, 158 different MIRU-VNTR patterns were identified. Clustering rate and minimum estimate of the proportion of TB caused by recent transmission was 4.1% and 8.1%, respectively.

CONCLUSIONS

The current study provided new insight into circulating genotypes of M.tb in PTB and EPTB patients in Tehran, Iran. This low percentage of TB transmission rate, demonstrated that mode of TB transmission was mainly associated with reactivation of latent TB rather than recently transmitted infection in this region. There was no significant difference in the association between the genotypes of M.tb strains and the site of the disease.

Challenge in direct Spoligotyping of Mycobacterium tuberculosis: a problematic issue in the region with high prevalence of polyclonal infections

OBJECTIVE

Based on our recent studies the prevalence of polyclonal infection in tuberculosis clinical specimens is more than 50% in Tehran, Iran. With this background, Spoligotyping was performed on clinical specimens and their respective cultures, and we examined whether mixed infections interfere with the results or not.

RESULTS

Based on the Spoligotyping pattern, among the fourteen patients, 57.1% had different genotypes in clinical samples and their respective cultures. These discrepant patterns were suggestive of polyclonal infections in clinical samples with possible overlapping Spoligotype patterns. We propose that in societies with high mixed infections (e.g. Iran), direct Spoligotyping on clinical samples can be controversial.

Prevalence of Beijing and Haarlem genotypes among multidrug-resistant Mycobacterium tuberculosis in Iran: Systematic review and meta-analysis

Antimicrobial drug resistance creates major problems in the control of tuberculosis (TB). Beijing and Haarlem genotypes of Mycobacterium tuberculosis are the prevalent genotypes responsible for multidrug resistant (MDR) TB worldwide. The aim of this study was to conduct a systematic review using meta-analysis to indicate the prevalence of Beijing and Haarlem genotypes among MDR-TB cases in Iran. Data sources of current study were 311 original articles (2006-2016) that were searched in several databases including Medline, Scopus, Embase, Cochrane library, and Iranian databases. Sixteen articles were selected for the prevalence of Beijing and Haarlem families among MDR-TB strains. Data were evaluated using meta-analysis and random effects models with the Meta-Analysis Software package Version 2.2 (Biostat, Englewood, NJ). Final investigation indicated 856 MDR samples in the 16 articles. Overall, the prevalence of Beijing and Haarlem genotypes among MDR-TB isolates in Iran was estimated to be 19.3% (95% CI, 13.1-27.5) and 18.7% (95% CI, 11.9-28.3) respectively. The studies conducted in northern Iran showing a significant association between Haarlem genotype and MDR is of particular concern. Certain refugee migration flows make this genotype of particular epidemiological and clinical concern because of its potential ability to endanger TB control programs in Iran.

Mycobacterium tuberculosis of the Beijing Genotype in Iran and the World Health Organization Eastern Mediterranean Region: A Meta-Analysis

OBJECTIVE

The Beijing genotype is a distinct genetic lineage of Mycobacterium tuberculosis, which is distributed worldwide, and may cause large outbreaks of multidrug resistance-tuberculosis (MDR-TB). The distribution of such strains in the Eastern Mediterranean region (EMR) is unclear, and clarifying the data is our purpose apart from the presence of Beijing TB in Iran.

METHODS

We searched Published literature from CINAHL Cochrane Library, Current Contents, Database of Abstracts of Reviews of Effects (DARE), ProQuest Google Scholar PubMed, PsycINFO, Thomson Reuters, (SID), and Medical Library (MedLib) to detect relevant studies from the year 2000 to July 2015 with the following keywords: M. tuberculosis, Beijing genotype, EMR, and drug resistance. Random-effect models were used to estimate the proportion of Beijing strains in STATA 14. Heterogeneity was investigated by subgroup analysis and meta-regression.

RESULTS AND CONCLUSION

The meta-prevalence of Beijing strains was 4% (CI 95% = 3-5). The prevalence was different based on types of detection techniques (spoligotyping = 4% vs. other techniques = 6%; p = 0.003) and years of study (before the year 2000 = 2% vs. after year 2000 = 4%, p = 0.004). The Beijing family was most prevalent in Iran and Pakistan. A strong relationship with drug resistance was reported in Pakistan and Iran, and an increasing trend was seen in Pakistan. Additional studies of drug-resistant TB distribution among Beijing strains in EMR countries are needed as well as a time-trend analysis of the Beijing strain infection in the region.

Prevalence of and risk factors for multidrug-resistant tuberculosis in Iran and its neighboring countries: systematic review and meta-analysis

Tuberculosis, in particular drug-resistant tuberculosis, is of global concern due to the high mortality and morbidity associated with it annually. The aim of this study was to determine the prevalence of and the risk factors for multidrug-resistant tuberculosis in Iran and its neighboring countries. Four databases (PubMed, BioMed Central, EMBASE, and Web of Science) were searched using key terms. Nineteen eligible articles were identified, of which 12 and seven were used for quantitative and qualitative analysis, respectively. The overall pooled estimate of the prevalence of multidrug-resistant tuberculosis, including both new and previously treated tuberculosis cases, in Iran, Iraq, Turkey and Pakistan was 16% (95% confidence interval [CI] 11-20). The patients with a previous tuberculosis treatment history (odds ratio [OR] = 6.45; 95% CI 5.12-7.79), those aged <45 years (OR = 1.57; 95% CI 1.12-2.03), and those who were males (OR = 1.83; 95% CI 1.19-2.48) had an increased pool risk of developing multidrug-resistant tuberculosis. The forest plot revealed that the pooled odds for the development of multidrug- resistant tuberculosis were 2.01 (95% CI 1.65-2.36). Poor adherence to treatment was one of the predictors of unsuccessful treatment outcomes. Multidrug-resistant tuberculosis is a great concern for public health programs in many countries globally, including those included in this review. The risk factors for the development of multidrug-resistant tuberculosis, specifically a previous tuberculosis treatment history, should be targeted through the implementation of specialized interventions.

Determining the Risk of Intra-Community Transmission of Tuberculosis in the Northwest of Iran Through 15 Loci Miru-Vntr Typing

This study was carried out in order to investigating the effect of travelling on the transmission of tuberculosis from high- to low-burden TB countries. Mycobacteria samples isolated from patients of distinct and relatively co-related countries (Azerbaijan Republic and Tabriz [located in the northwest of Iran]) were analyzed through 15 loci MIRU-VNTR typing method. PCR was done using special primers for each of the loci; then the number of allele repeats for all loci were determined by the size of their fragments. Finally, the created numeric patterns for each isolate were analyzed and clustered, using MIRU-VNTRplus.org website. All 119 isolates dispersing at 106 distinct patterns were composed of 10 clusters with 23 members and 96 unique patterns. Nine and five loci had high and moderate discriminatory power, respectively, but only one of them was poor in clustering. The study showed that 89.08% of TB cases involved resulted from the reactivation pattern and 10.92% were related to ongoing transmission. Although Azerbaijan Republic is a higher-burden TB region than Tabriz and Azerbaijan people make frequent tours to Tabriz to receive low or free medical services, the findings showed no TB transmission from the regions at least during the year of the study.

Mycobacterium tuberculosis lineages and anti-tuberculosis drug resistance in reference hospitals across Viet Nam

BACKGROUND

Mycobacterium tuberculosis, the tuberculosis (TB) pathogen, despite a low level of genetic diversity, has revealed a high variety of biological and epidemiological characteristics linked to their lineages, such as transmissibility, fitness and propensity to acquire drug resistance. This has important implications for the epidemiology of TB. We conducted this first countrywide cross-sectional study to identify the prevalent M. tuberculosis lineages and to assess their epidemiological associations and their relation to drug resistance. The study was conducted among isolates acquired in reference hospitals across Vietnam. Isolates with drug susceptibility testing profiles were identified for their lineages by spoligotyping. Logistic regression was used to investigate the association of M. tuberculosis lineages with location, age and sex of the patients and drug resistance levels.

RESULTS

Results showed that the most prevalent lineage was Beijing (55.4 %), followed by EAI (27.5 %), T (6.4 %), LAM (1.3 %), Haarlem (1 %) and Zero type (0.3 %). The proportion of Beijing isolates in the North (70.4 %) and the South (68 %) was higher than in the Centre (28 %) (OR = 1.7 [95 % CI: 1.4-2.0], p < 0.0001), whereas the proportion of EAI isolates in the North (7.1 %) and the South (17 %) was much lower compared with the Centre (59 %) (OR = 0.5 [95 % CI: 0.4-0.6], p < 0.0001). Overall, Beijing isolates were the most likely to be drug-resistant and EAI isolates were the least likely to be drug-resistant, except in the South of Vietnam where EAI is also highly drug-resistant. The proportion of Beijing isolates was significantly higher (p < 0.01), and the proportion of EAI isolates was significantly lower (p < 0.05) in younger patients. The proportion of drug-resistance was higher in isolates collected from male patients and from patients in the middle age groups.

CONCLUSIONS

The findings suggest ongoing replacement of EAI lineage, which is mainly more drug-susceptible with highly drug-resistant Beijing lineage in all studied regions of Vietnam. Male patients of working ages should be the focus for better control to prevent the emergence of drug-resistant TB.

Haarlem 3 is the predominant genotype family in multidrug-resistant and extensively drug-resistant Mycobacterium tuberculosis in the capital of Iran: A 5-year survey

The objective of this study was to further understand the genetic diversity of multidrug-resistant (MDR) and extensively drug-resistant (XDR) Mycobacterium tuberculosis isolates prevalent in Tehran, the capital city of Iran. From January 2010 to March 2015, a total of 723 M. tuberculosis strains were isolated from patients with pulmonary tuberculosis (TB). A total of 23 MDR, pre-XDR and XDR M. tuberculosis isolates were genotyped by spoligotyping and 24-loci mycobacterial interspersed repetitive unit-variable-number tandem repeat (MIRU-VNTR) typing. The results showed that the MDR, pre-XDR and XDR M. tuberculosis strains mainly belonged to the Haarlem 3 genotype (11/23; 47.8%), followed by the Beijing family (9/23; 39.1%). In addition, the 23 strains were clustered into 21 genotypes using a 24-loci MIRU-VNTR. In conclusion, Haarlem 3 genotype was the predominant genotype among the isolates from MDR-TB cases in this study, which could be of special concern.

Spatiotemporal Clustering of Mycobacterium tuberculosis Complex Genotypes in Florida: Genetic Diversity Segregated by Country of Birth

Background

Tuberculosis (TB) is caused by members of the Mycobacterium tuberculosis complex (MTBC). Although the MTBC is highly clonal, between-strain genetic diversity has been observed. In low TB incidence settings, immigration may facilitate the importation of MTBC strains with a potential to complicate TB control efforts.

Methods

We investigated the genetic diversity and spatiotemporal clustering of 2,510 MTBC strains isolated in Florida, United States, between 2009 and 2013 and genotyped using spoligotyping and 24-locus MIRU-VNTR. We mapped the genetic diversity to the centroid of patient residential zip codes using a geographic information system (GIS). We assessed transmission dynamics and the influence of immigration on genotype clustering using space-time permutation models adjusted for foreign-born population density and county-level HIV risk and multinomial models stratified by country of birth and timing of immigration in SaTScan.

Principal Findings

Among the 2,510 strains, 1,245 were reported among foreign-born persons; including 408 recent immigrants (<5 years). Strain allelic diversity (h) ranged from low to medium in most locations and was most diverse in urban centers where foreign-born population density was also high. Overall, 21.5% of cases among U.S.-born persons and 4.6% among foreign-born persons clustered genotypically and spatiotemporally and involved strains of the Haarlem family. One Haarlem space-time cluster identified in the mostly rural northern region of Florida included US/Canada-born individuals incarcerated at the time of diagnosis; two clusters in the mostly urban southern region of Florida were composed predominantly of foreign-born persons. Both groups had HIV prevalence above twenty percent.

Conclusions/Significance

Almost five percent of TB cases reported in Florida during 2009–2013 were potentially due to recent transmission. Improvements to TB screening practices among the prison population and recent immigrants are likely to impact TB control. Due to the monomorphic nature of available markers, whole genome sequencing is needed to conclusively delineate recent transmission events between U.S. and foreign-born persons.

Molecular Epidemiology of Mycobacterium Tuberculosis Strains in the North-West and West of Iran

Background:

Identifying Mycobacterium tuberculosis (MTB) transmission type is a key step in the control of this disease.

Aim:

This study aimed to determine the path and transmission type of MTB and the insertion sequence IS6110 band number and verify their relationship to demographic and clinical risk factors.

Subjects and Methods:

In this cross-sectional study, 64 MTB patients from three border provinces of Iran were selected after full clinical history and physical evaluation design. The drug susceptibility testing was carried out using the standard proportion technique on sputum samples. Isolates tested with restriction fragment length polymorphism technique used IS6110.

Results:

Recent transmission of disease was 33/50 (66%) based on clustering rate. The IS6110 band number had a significant relationship with drug resistance detected in proportion method tested by univariate linear regression (P < 0.01). Furthermore, the IS6110 band number had association with Bacillus Calmette–Guérin vaccination history (P = 0.02), sex (P < 0.01), and purified protein derivative (PPD) reaction size (P < 0.01) tested by multiple analysis. The risk of recent transmission inferred from the clustering rate was significantly higher in patients from Western provinces compared to those from the North-West province (P = 0.048). However, age (P = 0.39), gender (P = 0.16), vaccination history (P = 0.57), drug susceptibility, and PPD (P < 0.6) were independent of clustering. The largest cluster of up to six subjects was found in the Western provinces.

Conclusion:

Recent MTB transmission was much more common in the West compared to the North-West of Iran. Large MTB clusters with strong epidemiological links may be reflective of a disease outbreak. Correlation noted between the IS6110 band number and vaccination history; PPD size and female gender necessitates further studies.

Major infectious diseases affecting the Afghan immigrant population of Iran: a systematic review and meta-analysis

OBJECTIVES

As Afghans make up the largest group of foreign nationals in Iran, the aim of this study was to assess the proportion of Afghan immigrants among those afflicted by the most prevalent infectious diseases in Iran.

METHODS

National and international online scientific databases were searched through November 2013. The reference lists of included studies were also searched. All descriptive studies concerning the most common infectious diseases in Iran, including tuberculosis, multiple-drug-resistant tuberculosis, malaria, cholera, Crimean-Congo hemorrhagic fever, leishmaniasis, and hepatitis B were retrieved. The nationality of patients was not considered. The selection of studies and data extraction was performed separately by two authors. Results were reported using a random effect model with a 95% confidence interval (CI).

RESULTS

The overall proportion of Afghan immigrants with the aforementioned infectious diseases was 29% (95% CI, 21 to 37). According to a stratified analysis, the proportion of Afghan immigrants afflicted with tuberculosis was (29%), multiple-drug-resistant tuberculosis (56%), malaria (40%), cholera (8%), Crimean-Congo hemorrhagic fever (25%), leishmaniasis (7%), and hepatitis B (14%).

CONCLUSIONS

It is highly recommended to monitor the health status of the Afghan immigrants when entering Iran, to reduce the spread of communicable diseases, which are viewed as serious in international health regulations.

Estimation of Recent Transmission of Mycobacterium Tuberculosis Strains among Iranian and Afghan Immigrants: A Cluster-Based Study

BACKGROUND

Iran has extended borders with high-TB burden countries (Afghanistan and Pakistan) and immigrations of these populations influences TB distribution in the region and threatens the control strategies. The aim of this study was to evaluate the extent of recent TB transmission among Iranian and Afghan cases.

MATERIALS AND METHODS

Spoligotyping and 15-locus variable number tandem repeat (VNTR) typing were applied to genotype 102 MTB isolates (2009 to 2010). Phylogenetic relationships were analysed by two methods: a cluster-graph method and a minimum spanning tree (MST) method. Furthermore, evaluation of recent TB transmission was assessed with three indices including, RTIn, RTIn-1 and TMI.

RESULTS

Using molecular typing, 35 different spoligotypes were detected among the studied isolates. Seventy seven cases (75.4%) were distributed into 10 clusters and the remaining 25 (24.5%) isolates had a unique pattern. The cluster sizes also ranged from 2 to 21 isolates. The most frequent spoligotype in our populations belong to Haarlem (n=30, 29.4%) followed by CAS (n= 29, 28.4%) and Beijing (n=16, 15.6%) lineages. The used indices give the following values: RTIn = 0.75, RTIn-1 = 0.65 and TMI = 0.24.

CONCLUSION

The low rate of TB transmission in our findings (24%) showed that the mode of TB transmission in Iran is mostly associated with reactivation of a previous TB infection and that recently a transmitted disease has a minor role. However, the increasing incidence of the intra-community transmission in recent years highlights the need for establishing new strategies for control of TB.

Association of Mycobacterium Tuberculosis Lineages with IFN-γ and TNF-α Gene Polymorphisms among Pulmonary Tuberculosis Patient

The six major lineages of Mycobacterium tuberculosis [MTB] are found to be strongly associated with specific geographical outbreaks. But whether these bacterial lineages influence the host genetic polymorphism is uncertain. The present study was designed to evaluate the relevance of strain diversity and host genetic polymorphisms in susceptibility to pulmonary tuberculosis [PTB]. For this reason, single –nucleotide polymorphisms [SNPs] in interferon- γ [IFN-γ] receptor-1[G-611A], IFNG [G+ 2109A] and tumor necrosis factors [TNF-α] genes [at −238, 308,−857position] in patients [n=151] were analyzed and compared with controls [n=83]. The genetic diversity of M. tuberculosis isolates was performed using spacer oligonucleotide typing. Thereafter, the profile of IFN-γ and TNF-α allele frequency were investigated in each subtype of M.tuberculosis. The results showed C allele of TNF 857 and A allele of TNF 238 were more frequent in PTB cases [[TNF 857 C allele OR [CI95%] 0.6[0.4–0.9], p= 0.02] for TNF 238 A allele OR [CI95%] 5.5[3.4–9.0], p= 0.00]]. Similarly, G allele in IFNG+ 2109 A/G polymorphism were significantly more in patients than control subject[OR[CI95%] 0.3; p< 0.05]. The major identified clinical isolates of M. tuberculosis were EAI[42; 27.8% ], Haarlem[ 31; 20.5% ], CAS [ 23;15.2% ], Beijing[14; 9.2%], and T [11; 7.2% ] lineages. No correction was observed between strains diversity and frequency of SNPs in studied PTB cases. In conclusions, we exclude the possibility of genetic mutation in IFN-γ and TNF-α gene by different subtypes of M. tuberculosis. Although, our results supports a positive correlation between host SNPs and susceptibility to PTB.

High prevelance of rifampin-monoresistant tuberculosis: a retrospective analysis among Iranian pulmonary tuberculosis patients

We determined the prevalence of rifampin-monoresistant tuberculosis (RMR-TB) in Iran. Because development of RMR-TB is not common, we also identified the major risk factors associated with RMR-TB reported from different provinces of Iran. Data for 3,020 TB patients who remained or became smear positive after two, four, six, and nine months of standard first-line chemotherapy were retrospectively analyzed. Of 3,020 patients, 1,242 patients (41.1%) were culture and DNA positive for Mycobacterium tuberculosis. Of these patients, 73 (7.4%) patients had monoresistant isolates to rifampin, which was significantly higher than that for multidrug-resistant TB (5.8%). The average rate of RMR-TB in the studied population ranged from 5% to 10%. Classical investigation showed that 33.6% of patients had either a previous or family history of TB. Molecular epidemiology methods (i.e., spoligotyping and Mycobacterium interspersed repetitive unit-variable number tandem repeat), defined transmission link in three clusters (13%). These results outline the urgent need for a comprehensive plan for detection and treatment of RMR-TB cases.

Spoligotyping and drug resistance patterns of Mycobacterium tuberculosis isolates from five provinces of Iran

Tuberculosis (TB) persists as a public health problem in Iran. Characterization of Mycobacterium tuberculosis isolates circulating in this area will contribute to understand and control the spread of the strains. The aims of this study were to understand the genetic diversity and drug susceptibility of M. tuberculosis isolates circulating in Iran and to analyze the relationship between genotype and drug resistance. A total of 291 M. tuberculosis isolates collected from TB patients were genotyped by spoligotyping. Drug susceptibility testing was performed using proportion method. Spoligotyping resulted in 75 distinct patterns. 86.2% of isolates were grouped in 35 clusters while the remaining isolates were unique. Ural was found to be the most predominant lineage (34.3%) followed by Central Asian strain (CAS) (24%), T (18.2%), Manu2 (7.5%) and Latin American-Mediterranean (LAM) (6.1%). The five largest clusters were Ural/Spoligotype International Type (SIT)127 (15.8%), CAS1/SIT26 (9.2%), T1/SIT53 (6.1%), T1/SIT284 (5.4%), and CAS1/SIT25 (4.4%). About 5% of isolates had multidrug resistance (MDR) and 10% had other resistance. MDR was significantly associated with Beijing strains, but not with Ural family. This study highlights dominance of Ural, CAS, and T families in Iran. Biogeographic specificity of CAS and T families to border provinces of Iran including Sistan-Baluchestan and Kermanshah, respectively, suggested that this family strains might be transmitted from these regions to other provinces of the country.

Insights into the origin, emergence, and current spread of a successful Russian clone of Mycobacterium tuberculosis

Mycobacterium tuberculosis variant Beijing B0/W148 is regarded as a successful clone of M. tuberculosis that is widespread in the former Soviet Union and respective immigrant communities. Understanding the pathobiology and phylogeography of this notorious strain may help to clarify its origin and evolutionary history and the driving forces behind its emergence and current dissemination. I present the first review and analysis of all available data on the subject. In spite of the common perception of the omnipresence of B0/W148 across post-Soviet countries, its geographic distribution shows a peculiar clinal gradient. Its frequency peaks in Siberian Russia and, to a lesser extent, in the European part of the former Soviet Union. In contrast, the frequency of B0/W148 is sharply decreased in the Asian part of the former Soviet Union, and it is absent in autochthonous populations elsewhere in the world. Placing the molecular, clinical, and epidemiological features in a broad historical, demographic, and ecological context, I put forward two interdependent hypotheses. First, B0/W148 likely originated in Siberia, and its primary dispersal was driven by a massive population outflow from Siberia to European Russia in the 1960s to 1980s. Second, a historically recent, phylogenetically demonstrated successful dissemination of the Beijing B0/W148 strain was triggered by the advent and wide use of modern antituberculosis (anti-TB) drugs and was due to the remarkable capacity of this strain to acquire drug resistance. In contrast, there is some indication, but not yet systematic proof, of an enhanced virulence of this strain.

Respiratory disorders in the Middle East: a review

The spectrum of pulmonary pathology in the Middle East is as versatile as its civilizations and cultures. In this review, we outline the key challenges confronting pulmonologists in the Middle East. We shed light on the diverse conditions commonly encountered in the region, from the centuries-old illnesses of tuberculosis, to contemporary problems such as lung complications from chemical warfare. We specifically highlighted unique aspects related to respiratory illnesses in the Middle East, for example, climate factors in the desert region, cultural habits, for example, water-pipe smoking and disorders unique to the region, such as Behçet's disease. Pulmonologists are also faced with the consequences of modernization, including large immigrant population and associated social and health issues, rising incidence of obesity and sleep apnoea, and drug-resistant tuberculosis. Tackling these health issues will require an integrated approach involving public health, primary care as well as specialist pulmonology input, taking into consideration the unique cultural and environmental factors to ensure effective management and compliance to medical care.

The quiet and controversial: Ural family of Mycobacterium tuberculosis

The absence of lateral gene exchange is a characteristic feature defining the genome evolution and clonal population structure of Mycobacterium tuberculosis. Certain of its lineages have justly attracted more attention due to their global dissemination and/or remarkable pathogenic properties. In this critical review, I discuss the population structure and genetic geography of the less 'popular' but in some aspects no less noteworthy M. tuberculosis lineage, Ural family. Its specific signature was initially defined by single copy in MIRU26, and large (>6) copy number in MIRU10 loci, and by 43-spoligotyping as absence of signals 29-31 and 33-36. Here, I suggest to subdivide Ural strains with present and absent spoligosignal 2 into primary Ural-1 and secondary Ural-2 sublineages, respectively, while 1 copy in MIRU26 is specific of Ural-1. Furthermore, three copies were recently described in MIRU10 in Ural-1 strains which highlights a high diversity of this locus in Ural genotype. The data on the two Ural sublineages were extracted from SpolDB4 database and original publications in order to trace their distribution at global and within-country levels. Importantly, the rigorous reanalysis suggested the true rate of the Ural genotype in the Ural area in Russia to be only 7%. In contrast, the frequencies of the Ural sublineages peak elsewhere: in South Ukraine and Georgia/Abkhazia (Ural-1, up to 14-19%), and in southwestern Iran (Ural-2, up to 26%). However, as this name is used since 2005, it seems most parsimonious to continue its use even if misleading. The forest graph was built on the available spoligoprofiles of Ural family strains from Eurasia. It helped to suggest routes of their primary dispersal that are discussed in the context of the known human migrations also influenced by natural barriers. The north/east Pontic area may have been an area of origin and primary dispersal of the Ural (Ural-1) genotype in Eurasia, whereas political and natural borders may have influenced its subsequent dissemination throughout Central Asia. Studies of phenotypic properties in different models, comparison with host genetics give evidence that the Ural family strains are not associated with increased capacity to acquire drug resistance, pathogenicity or transmissibility. Instead since Ural family is rather moderately widespread in Eurasia beyond the hypothesized areas of origin, this situation may be a result of its low contagiosity as a consequence of long-term co-adaptation with human host. Future research should be focused on whole-genome sequencing in order to identify Ural-specific SNP and/or deletion, to resolve its phylogenetic and phylogeographic uncertainty and to elucidate biological features underlying its circulation and co-evolution with the human species.

Prevalence of Mycobacterium tuberculosis in Taiwan: A Model for Strain Evolution Linked to Population Migration

The global evolution and spread of Mycobacterium tuberculosis (MTB), one of the most successful bacterial pathogens, remain a mystery. Advances in molecular technology in the past decade now make it possible to understand MTB strain evolution and transmission in the context of human population migration. Taiwan is a relatively isolated island, serving as a mixing vessel over the past four centuries as colonization by different waves of ethnic groups occurred. By using mycobacterial tandem repeat sequences as genetic markers, the prevalence of MTB strains in Taiwan revealed an interesting association with historical migrations of different ethnic populations, thus providing a good model to explore the global evolution and spread of MTB.

Spoligotype-based comparative population structure analysis of multidrug-resistant and isoniazid-monoresistant Mycobacterium tuberculosis complex clinical isolates in Poland

The spoligotyping-based population structure of multidrug-resistant (MDR) Mycobacterium tuberculosis strains isolated in Poland (n = 46), representing all culture-positive MDR tuberculosis (MDR-TB) cases, was compared to that of isoniazid (INH)-monoresistant strains (n = 71) isolated in 2004. The latter data set from a previous study (E. Augustynowicz-Kopeć, T. Jagielski, and Z. Zwolska, J. Clin. Microbiol. 2008, 46:4041-4044) represented 87% of all INH-monoresistant strains. The clustering rates and genotypic-diversity indexes for the 2 subpopulations were not significantly different (P = 0.05). The results were entered in the SITVIT2 database to assign specific shared type designations, corresponding genotypic lineages, and geographical distributions and compared to available data from neighboring countries (Germany, n = 704; Czech Republic, n = 530; Sweden, n = 379; Kaliningrad, Russia, n = 90) and strains from previous studies in Poland (n = 317). MDR strains resulted in 27 patterns (20 unique strains within the study and 7 clusters containing 2 to 6 isolates per cluster with a clustering rate of 56.5%) and belonged to the following genotypic lineages: ill-defined T family (28.3%), Haarlem (17.4%), Latin American and Mediterranean (LAM) (13%), Beijing (8.7%), S family (4.35%), and the X clade (2.17%). Comparison of the genetic structure of the MDR strains with that of INH-monoresistant strains showed that a total of 9 patterns were shared by both groups; these represented 1/3 of the MDR strains and 2/3 of the INH-monoresistant strains. Interestingly, 76.1% of the MDR isolates and 71.8% of the INH-resistant isolates yielded spoligotypes that were previously reported from Poland. The observation that nearly half of the spoligotypes identified among both MDR (48.1%) and INH-monoresistant (43.3%) M. tuberculosis isolates were present in Poland's neighboring countries suggested that a significant proportion of MDR and INH-resistant TB cases in Poland were caused by strains actively circulating in Poland or its neighbors. Our results corroborate the leading role of the T and Haarlem genotypes in the epidemiology of drug-resistant TB in Poland. Nevertheless, the LAM and Beijing family strains that infected, correspondingly, 13% and 9% of patients with MDR-TB were absent among the strains from patients with INH-monoresistant TB, suggesting that a proportion of MDR-TB cases in Poland are due to ongoing transmission of MDR clones exhibiting specific genotypes. Study of the population genetic relationships between MDR and INH-monoresistant strains by drawing minimum spanning trees showed that ill-defined T1 sublineage strains (1/3 of all INH-monoresistant strains), represented by its prototype, SIT53, constituted the central node of the tree, followed by strains belonging to the well-defined H3, H1, and S subgroups. However, the MDR group, in addition, contained LAM (n = 6) and Beijing (n = 4) lineage isolates. With the exception of the 4 Beijing lineage strains in the latter group and a single orphan isolate in the INH-monoresistant group, none of the remaining 112/117 isolates belonged to principal genetic group 1 (PGG1) in our study. Given the high rate of clustering and the near absence of immigrants in the study, the persistence of MDR-TB in Poland seems to result from active transmission of MDR strains within the autochthonous population, the bulk of it caused by evolutionarily recent tubercle bacilli.

DNA repair systems and the pathogenesis of Mycobacterium tuberculosis: varying activities at different stages of infection

Mycobacteria, including most of all MTB (Mycobacterium tuberculosis), cause pathogenic infections in humans and, during the infectious process, are exposed to a range of environmental insults, including the host's immune response. From the moment MTB is exhaled by infected individuals, through an active and latent phase in the body of the new host, until the time they reach the reactivation stage, MTB is exposed to many types of DNA-damaging agents. Like all cellular organisms, MTB has efficient DNA repair systems, and these are believed to play essential roles in mycobacterial pathogenesis. As different stages of infection have great variation in the conditions in which mycobacteria reside, it is possible that different repair systems are essential for progression to specific phases of infection. MTB possesses homologues of DNA repair systems that are found widely in other species of bacteria, such as nucleotide excision repair, base excision repair and repair by homologous recombination. MTB also possesses a system for non-homologous end-joining of DNA breaks, which appears to be widespread in prokaryotes, although its presence is sporadic within different species within a genus. However, MTB does not possess homologues of the typical mismatch repair system that is found in most bacteria. Recent studies have demonstrated that DNA repair genes are expressed differentially at each stage of infection. In the present review, we focus on different DNA repair systems from mycobacteria and identify questions that remain in our understanding of how these systems have an impact upon the infection processes of these important pathogens.

Mycobacterium tuberculosis genotypic diversity in pyrazinamide-resistant isolates of Iran

Pyrazinamide (PZA) is an important first-line drug used for the short-course treatment of tuberculosis in combination with isoniazid and rifampin. It has been reported that mutations in pncA gene correlate well with PZA resistance depending on the geographic area. On the other hand, different genotypes of Mycobacterium tuberculosis show different affinities to acquire resistance-related mutations. To determine the relative significance of various mutations in the pncA gene in Iranian PZA-resistant M. tuberculosis isolates and to analyze the association of different genotypes of M. tuberculosis with PZA resistance, 34 PZA-resistant M. tuberculosis isolates were analyzed for their pncA mutations using direct sequencing. These isolates were genotyped by IS6110 fingerprinting and spoligotyping methods. Mutations in the pncA gene were identified in 24 of 34 of these isolates (70.58%). No mutations were found in 10 PZA-resistant isolates, which implied that alternative mechanisms of resistance existed in these strains. PZA resistance was strongly (41.2%) associated with multidrug-resistant tuberculosis. Genotyping revealed the Central Asian (CAS) and East-African Indian families as the most prevalent families between PZA-monoresistant isolates versus the Beijing and Haarlem families which were the most frequent families between PZA including multidrug-resistant isolates.

Emergence of new forms of totally drug-resistant tuberculosis bacilli: super extensively drug-resistant tuberculosis or totally drug-resistant strains in iran

BACKGROUND

The study documented the emergence of new forms of resistant bacilli (totally drug-resistant [TDR] or super extensively drug-resistant [XDR] tuberculosis [TB] strains) among patients with multidrug-resistant TB (MDR-TB).

METHODS

Susceptibility testing against first- and second-line drugs was performed on isolated Mycobacterium tuberculosis strains. Subsequently, the strains identified as XDR or TDR M tuberculosis were subjected to spoligotyping and variable numbers of tandem repeats (VNTR).

RESULTS

Of 146 MDR-TB strains, 8 XDR isolates (5.4%) and 15 TDR isolates (10.3%) were identified. The remaining strains were either susceptible (67%) or had other resistant patterns (20%). Overall, the median of treatments and drugs previously received by MDR-TB patients was two courses of therapy of 15 months' duration with five drugs (isoniazid [INH], rifampicin [RF], streptomycin, ethambutol, and pyrazinamide). The median of in vitro drug resistance for all studied cases was INH and RF. The XDR or TDR strains were collected from both immigrants (Afghan, 30.4%; Azerbaijani, 8.6%; Iraqi, 4.3%) and Iranian (56.5%) MDR-TB cases. In such cases, the smear and cultures remained positive after 18 months of medium treatment with second-line drugs (ethionamide, para-aminosalicylic acid, cycloserine, ofloxacin, amikacin, and ciprofloxacin). Spoligotyping revealed Haarlem (39.1%), Beijing (21.7%), EAI (21.7%), and CAS (17.3%) superfamilies of M tuberculosis. These superfamilies had different VNTR profiles, which eliminated the recent transmission among MDR-TB cases.

CONCLUSIONS

The isolation of TDR strains from MDR-TB patients from different regional countries is alarming and underlines the possible dissemination of such strains in Asian countries. Now the next question is how one should control and treat such cases.

Molecular analysis of isoniazid resistance in different genotypes of Mycobacterium tuberculosis isolates from Iran

Considering the significant increase of isoniazid (INH) resistance in Iranian Mycobacterium tuberculosis isolates in the last few years and to investigate the prevalence and diagnostic potential of the most commonly reported mutations associated with INH resistance in Iran, we analyzed parts of the katG gene and fabG1-inhA and oxyR-ahpC regulatory regions in a sample of 48 INH-resistant and 25 INH-sensitive isolates. Mutations in the katG 315, fabG1-inhA, and oxyR-ahpC regulatory regions were detected in 58.3%, 18.7%, and 39.6% of isolates, respectively. The R463L polymorphism in the katG gene and the ahpC46A were detected with high frequency in both INH-resistant and -sensitive isolates. Spoligotyping and IS6110-based restriction fragment length polymorphism patterns revealed that most of the isolates containing ahpC46A and katG 463Leu polymorphism belonged to the Central Asian (CAS) super family. The tight relationship between ahpC46A and katG 463Leu polymorphisms and the CAS super family highlights the importance of the CAS super family in INH resistance in Iran. In conclusion, mutations at katG codon 315 or the fabG1-inhA regulatory region were identified in 77.0% of the INH-resistant isolates and in none of the INH-sensitive strains, and are highly predictive of isonizid resistance in Iranian isolates.

The recent-transmission of Mycobacterium tuberculosis strains among Iranian and Afghan relapse cases: a DNA-fingerprinting using RFLP and spoligotyping

BACKGROUND

Relapse of tuberculosis (TB) may develop as the result of reactivation of the endogenous primary infection, or as a result of a exogenous reinfection. This survey evaluated the rate of reactivation versus recent transmission among Iranian and Afghan relapse cases.

METHODS

The sputum specimens were digested, examined microscopically for acid-fast bacilli, and inoculated into Löwenstein-Jensen slants by standard procedures. Thereafter, the susceptibility and identification tests were performed on culture positive specimens. Subsequently, the strains that were identified as Mycobacterium tuberculosis (258 isolates) were subjected to IS6110 restriction fragment length polymorphism (RFLP) and spoligotyping. Additional patient's information was collected for further epidemiological analysis. Patients whose isolates had identical genotyping patterns were considered a cluster with recent transmission episode.

RESULTS

Out of 258 available isolates, 72(28%) had multi-drug resistant (MDR-TB) in ratio and 42 (16.2%) had other resistant. Notably, 38 of MDR-TB cases (52%) were isolated from Afghan patients. By IS6110-RFLP typing method, 65 patients (25%) were clustered in 29 clusters. In cluster cases, the intra-community transmissions between Iranian and Afghan patients were 41%. All MDR-TB patients in clusters had either Haarlem I or Beijing characteristic. The risk factors like sex, family history, close contact, living condition, PPD test result and site of TB infection were not associated with clustering. Although, the MDR-TB strains were more frequent in non-cluster cases (31%) than cluster one(18%) (P < 0.05). Majority of M. tuberculosis strains isolated from non-cluster cases were belong to EAI3 (51; 30%) and CASI(32;18.6%) superfamilies.

CONCLUSION

During the studied period, reactivation of a previous infection remain the more probable cause of recurrence. Although, the evidence of intra- community transmission between Iranian and Afghan TB cases, highlighted the impact of afghan immigrants in national tuberculosis control program (NTP) of Iran.

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.

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.

Beijing and Haarlem genotypes are overrepresented among children with drug-resistant tuberculosis in the Western Cape Province of South Africa

Drug resistance among children with culture-confirmed tuberculosis (TB) provides an accurate measure of transmitted drug resistance within the community. We describe the genotype diversity in children with culture-confirmed TB and investigate the relationship between genotype and drug resistance. A prospective study was conducted from March 2003 through August 2005 at Tygerberg Children's Hospital, in the Western Cape Province of South Africa. All children (<13 years of age) diagnosed with culture-confirmed TB were included. Genotype analysis and phenotypic drug susceptibility testing were performed on the first culture-positive isolate from each patient. Mutation analysis was performed on all drug-resistant isolates. Spoligotyping was successfully performed on isolates from 391/399 (98%) children diagnosed with culture-confirmed TB. Drug susceptibility testing was also performed on 391 isolates; 49 (12.5%) were resistant to isoniazid, and 20 (5.1%) of these were resistant to both isoniazid and rifampin. Beijing was the most common genotype family, identified in 130/391 (33.2%) cases, followed by LAM in 114/391 (29.2%) cases. The presence of both Beijing and Haarlem genotype families was significantly associated with drug resistance (26/49 [53.1%] versus 113/342 [33.0%]; odds ratio, 1.7; 95% confidence interval, 1.0 to 2.9). The high prevalence of Beijing and LAM in children with culture-confirmed TB reflects considerable transmission of these genotype families within the community. The overrepresentation of Beijing and Haarlem genotype families in children with drug-resistant TB demonstrates their contribution to transmitted drug resistance and their potential importance in the emergent drug-resistant TB epidemic.