Real-time PCR assay for rapid detection of epidemiologically and clinically significant Mycobacterium tuberculosis Beijing genotype isolates

Prevalence of Beijing Central Asian/Russian Cluster 94-32 among Multidrug-Resistant M. tuberculosis in Kazakhstan

The Beijing genotype is the most distributed M. tuberculosis family in Kazakhstan. In this study, we identified dominant Beijing clusters in Kazakhstan and assessed their drug susceptibility profiles and association with the most widely spread mutation Ser531Leu of the rpoB gene and the mutation Ser315Thr of the katG gene associated with resistance to rifampicin and isoniazid, respectively. M. tuberculosis isolates (n = 540) from new TB cases were included in the study. MIRU-VNTR genotyping was performed for 540 clinical isolates to determine M. tuberculosis families using 24 loci. RD analysis was additionally performed for the Beijing isolates. The identification of mutations in the drug-resistance genes of M. tuberculosis was performed with allele-specific real-time PCR and Sanger sequencing. The Beijing genotype was identified in 60% (324/540) of the clinical isolates. Central Asian/Russian cluster 94-32 was the most distributed cluster among the Beijing isolates (50.3%; 163/324). Three other dominant Beijing clusters were identified as 94-33 (3.4%; 11/324), 100-32 (3.1%; 10/324) and 99-32 (3.1%; 10/324). The Beijing genotype was associated with drug-resistant TB (p < 0.0001), including multidrug-resistant TB (p < 0.0001), in our study. An association of the mutation Ser531Leu of the rpoB gene with the Beijing genotype was found (p < 0.0001; OR = 16.0000; 95%CI: 4.9161-52.0740). Among the Beijing isolates, cluster 94-32 showed an association with MDR-TB (p = 0.021). This is why the evaluation of the Beijing genotype and its clusters is needed to control MDR-TB in Kazakhstan.

Genomic Characterization of Drug-Resistant Mycobacterium tuberculosis L2/Beijing Isolates from Astana, Kazakhstan

Kazakhstan ranks among the countries with the highest number of MDR-TB patients per 100,000 population worldwide. The successful transmission of local MDR strains of Mycobacterium tuberculosis (Mtb) poses a significant threat to disease control. In this study, we employed whole-genome sequencing to examine drug resistance, compensatory mutations, population structure, and transmission patterns in a sample of 24 clinical isolates of L2/Beijing Mtb collected in Astana, Kazakhstan between 2021 and 2022. The genotypic prediction of Mtb susceptibility to anti-TB agents was consistent with the phenotypic susceptibility, except for bedaquiline. An analysis of resistance-associated genes characterized most of the isolates as pre-extensively drug-resistant tuberculosis (pre-XDR-TB) (n = 15; 62.5%). The phylogenetic analysis grouped the isolates into four transmission clusters; the dominant cluster was assigned to the "aggressive" Central Asia outbreak (CAO) clade of L2/Beijing (n = 15; 62.5%). Thirteen mutations with putative compensatory effects were observed exclusively in Mtb isolates containing the rpoB S450L mutation. The putative compensatory mutations had a stabilizing effect on RpoABC protein stability and dynamics. The high prevalence of the CAO clade in the population structure of Mtb may explain the rapid spread of MDR-TB in Kazakhstan.

Genetic Diversity and Primary Drug Resistance of Mycobacterium tuberculosis Beijing Genotype Strains in Northwestern Russia

The Beijing genotype is the main family of Mycobacterium tuberculosis in Russia. We analyzed its diversity and drug resistance in provinces across Northwestern Russia to identify the epidemiologically relevant Beijing strains. The study collection included 497 isolates from newly-diagnosed tuberculosis (TB) patients. Bacterial isolates were subjected to drug-susceptibility testing and genotyping. The Beijing genotype was detected in 57.5% (286/497); 50% of the Beijing strains were multidrug-resistant (MDR). Central Asian/Russian and B0/W148 groups included 176 and 77 isolates, respectively. MDR was more frequent among B0/W148 strains compared to Central Asian/Russian strains (85.7% vs. 40.3%, p < 0.0001). Typing of 24 minisatellite loci of Beijing strains revealed 82 profiles; 230 isolates were in 23 clusters. The largest Central Asian/Russian types were 94-32 (n = 75), 1065-32 (n = 17), and 95-32 (n = 12). B0/W148 types were 100-32 (n = 59) and 4737-32 (n = 5). MDR was more frequent in types 1065-32 (88.2%), 100-32 (83.1%), and 4737-32 (100%). In contrast, type 9391-32 (n = 9) included only drug-susceptible strains. To conclude, M. tuberculosis Beijing genotype is dominant in Northwestern Russia, and an active transmission of overwhelmingly MDR B0/W148 types explains the reported increase of MDR-TB. The presence of MDR-associated minor variants (type 1071-32/ancient Beijing and Central Asia Outbreak strain) in some of the studied provinces also requires attention.

Tuberculosis in the Russian Federation: Dynamics of the Epidemic Indicators before and after COVID-19 Pandemic

The measures taken against tuberculosis (TB) in recent years in the Russian Federation have been highly effective. Unfortunately, the COVID-19 pandemic may seriously undermine the progress that has been made in the fight against TB. The aim of this study was to assess changes in the epidemiological rates of tuberculosis in the Russian Federation before and after the COVID-19 pandemic. Materials and methods. The analysis was conducted by considering the main epidemiological indicators of tuberculosis, according to the federal statistics for the period from 2017 to 2021. The parameters were estimated according to the data received from 11 areas in the North-Western region. Statistical analysis was carried out using the free software computing environment R (v.3.5.1) and the commercial software package Statistical Package for the Social Sciences (SPSS Statistics for Windows, version 24.0, IBM Corp., 2016). Research results. We found a positive correlation between the incidence among the overall population and the incidence among children aged 0–17, inclusively (r = 0.55 in 2017, r = 0.60 in 2020, and r = 0.53 in 2021). Along with the received regularities, a different trend is shown in the data analysis of general incidence and health X-ray examination for tuberculosis among the general population. The correlation has decreased threefold from 2017 (r = 0.72) to 2020 (r = 0.32); this negative trend might be the result of factors such as the quality of X-ray screening examinations among the general population, and the reduced assessment objectivity of the tuberculosis incidence rate. Conclusions. In assessing the correlation between general incidence and incidence in children under 17 years of age, as well as between incidence and mortality in the Russian Federation, a positive correlation was found with an increasing trend. Such a discrepancy might be due to decreases in the occupational health examination coverage among the general population. Therefore, in the years ahead, we can expect epidemiological indicators to increase incidence and mortality, including child mortality, associated with the insufficient detection of tuberculosis among the population during the COVID-19 pandemic.

Population structure of Mycobacterium tuberculosis from referral clinics in Western Siberia, Russia: Before and during the Covid-19 pandemic

The dramatic change in global health imposed by the Covid-19 pandemic has also impacted TB control. The TB incidence decreased dramatically not because of the improved situation but due to undertesting, reduced resources, and ultimately, substantially reduced detection rate. We hypothesized that multiple and partly counteracting factors could influence changes in the local Mycobacterium tuberculosis population. To test this hypothesis, we analyzed M. tuberculosis isolates collected in Western Siberia, Russia, before and during the Covid-19 pandemic. A total of 269 M. tuberculosis isolates from patients admitted at referral clinics were studied. The pre-pandemic and pandemic collections included 179 and 90 isolates, respectively. Based on genotyping, both pre-pandemic and pandemic samples are heavily dominated by the Beijing genotype isolates (95% and 88%) that were mostly MDR (80 and 68%). The high proportion of MDR isolates is due to the specific features of the studied collections biased towards patients with severe TB admitted at the National referral center in Novosibirsk. While no dramatic change was observed in the M. tuberculosis population structure in the survey area in Western Siberia during the Covid-19 pandemic in 2020–2021 compared to the pre-pandemic collection, still we note a certain decrease of the Beijing genotype and an increase in the proportion and diversity of the non-Beijing isolates. However, the transmissible and MDR Beijing B0/W148 did not increase its prevalence rate during the pandemic. More generally, the high prevalence rate of the Beijing genotype and its strong association with MDR both before and during the pandemic are alarming features of this region in Western Siberia, Russia.

Impact of pathobiological diversity of Mycobacterium tuberculosis on clinical features and lethal outcome of tuberculosis

BACKGROUND

Mycobacterium tuberculosis population in Russia is dominated by the notorious Beijing genotype whose major variants are characterized by contrasting resistance and virulence properties. Here we studied how these strain features could impact the progression of pulmonary tuberculosis (TB) concerning clinical manifestation and lethal outcome.

RESULTS

The study sample included 548 M. tuberculosis isolates from 548 patients with newly diagnosed pulmonary TB in Omsk, West Siberia, Russia. Strains were subjected to drug susceptibility testing and genotyping to detect lineages, sublineages, and subtypes (within Beijing genotype). The Beijing genotype was detected in 370 (67.5%) of the studied strains. The strongest association with multidrug resistance (MDR) was found for epidemic cluster Beijing B0/W148 (modern sublineage) and two recently discovered MDR clusters 1071-32 and 14717-15 of the ancient Beijing sublineage. The group of patients infected with hypervirulent and highly lethal (in a mouse model) Beijing 14717-15 showed the highest rate of lethal outcome (58.3%) compared to Beijing B0/W148 (31.4%; P = 0.06), Beijing Central Asian/Russian (29.7%, P = 0.037), and non-Beijing (15.2%, P = 0.001). The 14717-15 cluster mostly included isolates from patients with infiltrative but not with fibrous-cavernous and disseminated TB. In contrast, a group infected with low virulent 1071-32-cluster had the highest rate of fibrous-cavernous TB, possibly reflecting the capacity of these strains for prolonged survival and chronicity of the TB process.

CONCLUSIONS

The group of patients infected with hypervirulent and highly lethal in murine model 14717-15 cluster had the highest proportion of the lethal outcome (58.3%) compared to the groups infected with Beijing B0/W148 (31.4%) and non-Beijing (15.2%) isolates. This study carried out in the TB high-burden area highlights that not only drug resistance but also strain virulence should be considered in the implementation of personalized TB treatment.

Role of ESAT-6 in pathogenicity of Beijing and non-Beijing Mycobacterium tuberculosis isolates

BACKGROUND

Mycobacterium tuberculosis Beijing genotype was associated with tuberculosis outbreaks and increased transmissibility. To understand the variation in virulence between Beijing and non-Beijing clinical isolates of M.tuberculosis genotypes, the esat-6 gene sequencing, and its expression was compared in the macrophage environment.

MATERIALS & METHODS

Among 64 nonrepetitive, culture-positive M.tuberculosis, DNA extraction of 24 and 40 pure confirmed Beijing and non-Beijing isolates was accompanied by the boiling method. esat-6 gene PCR amplification and their sequencing were carried out by specific primers and its expression was performed on human macrophage cell line U937 after 6, 12, and 18 h of exposure to bacilli. The esat-6 mRNA transcription and expression in M. tuberculosis treated macrophage by Real-Time PCR and Western blot method.

RESULTS

Data analysis based on sequencing of the east-6 gene PCR product showed that this gene exists in all isolates and there are no changes or single nucleotide variation between the Beijing and non-Beijing isolates. In Beijing strains, the esat-6 expression was increased during the study times, but it was constant in non-Beijing isolates. esat-6 gene expression in Beijing isolates reached to about 44.9 times more than non-Beijing isolates after 18 h incubation on the macrophages cell line.

CONCLUSION

esat-6 is a conserved gene both in Beijing and non-Beijing isolates of M.tuberculosis. More expression of the east-6 gene in the macrophage model may indicate that this gene is likely to play a more important role in increasing the pathogenicity of Beijing strains.

Revisiting the methods for detecting Mycobacterium tuberculosis: what has the new millennium brought thus far?

Tuberculosis (TB) affects around 10 million people worldwide in 2019. Approximately 3.4 % of new TB cases are multidrug-resistant. The gold standard method for detecting Mycobacterium tuberculosis, which is the aetiological agent of TB, is still based on microbiological culture procedures, followed by species identification and drug sensitivity testing. Sputum is the most commonly obtained clinical specimen from patients with pulmonary TB. Although smear microscopy is a low-cost and widely used method, its sensitivity is 50-60 %. Thus, owing to the need to improve the performance of current microbiological tests to provide prompt treatment, different methods with varied sensitivity and specificity for TB diagnosis have been developed. Here we discuss the existing methods developed over the past 20 years, including their strengths and weaknesses. In-house and commercial methods have been shown to be promising to achieve rapid diagnosis. Combining methods for mycobacterial detection systems demonstrates a correlation of 100 %. Other assays are useful for the simultaneous detection of M. tuberculosis species and drug-related mutations. Novel approaches have also been employed to rapidly identify and quantify total mycobacteria RNA, including assessments of global gene expression measured in whole blood to identify the risk of TB. Spoligotyping, mass spectrometry and next-generation sequencing are also promising technologies; however, their cost needs to be reduced so that low- and middle-income countries can access them. Because of the large impact of M. tuberculosis infection on public health, the development of new methods in the context of well-designed and -controlled clinical trials might contribute to the improvement of TB infection control.

Spatiotemporal dynamics of drug-resistant Mycobacterium tuberculosis: Contrasting trends and implications for tuberculosis control in EU high-priority country

Different and contrasting trends related to human migration and the implementation of health control programmes influence the spread of drug-resistant tuberculosis (TB). We analysed the Mycobacterium tuberculosis population structure in Estonia, a high-priority EU country for TB control, to detect the dynamic changes and underlying factors. The study collection included 278 M. tuberculosis isolates recovered in 1999 and 2014-2015. The isolates were subjected to drug susceptibility testing, genotyping and analysis of sublineage/cluster-specific markers and drug resistance mutations. The Beijing genotype was the most prevalent, and its rate increased from 28.6% in 1999 to 38.5% in 2015 (p = .09). The non-Beijing strains represented Euro-American lineage (Latin American Mediterranean [LAM], Ural, Haarlem, T, X genotypes) and Indo-Oceanic lineage (one EAI-IND isolate). The proportion of isolates resistant to two or more drugs increased from 22.4% to 29.1% (p = .1). The pre-XDR/XDR isolates were identified only within the Beijing genotype. In contrast, the drug resistance rate decreased in the LAM genotype from 42.1% to 11.8% (p = .05). The Beijing B0/W148-cluster ('successful Russian strain') included only MDR, pre-XDR or XDR isolates. All B0/W148-cluster isolates were resistant to two or more drugs compared to 28% of the Beijing 94-32-cluster (p = .0002). The Beijing genotype was not identified in the isolates from patients born in Estonia before 1940 compared to its 35.2% rate among other patients. In summary, the circulation of the highly drug-resistant isolates of the Beijing B0/W148 subtype, the increased prevalence of the Beijing genotype among HIV-coinfected patients and the increased number of patients with alcohol abuse (47.5%) present major challenges of the current TB control in Estonia. The Beijing genotype was likely brought to Estonia after 1945 due to the massive human influx from the Soviet Union. In contrast, the main genotypes of the Euro-American lineage were likely endemic in Estonia during all 20th century.

Increased transmissibility of Russian successful strain Beijing B0/W148 of Mycobacterium tuberculosis: Indirect clues from history and demographics

The local situation with tuberculosis (TB) is shaped by the complex interplay of multiple factors related to both human host and Mycobacterium tuberculosis. We hypothesized that TB epidemiology in the rural regions in the Soviet Union was impacted by construction of the Gulag camps and significant incoming migration. This molecular M. tuberculosis study was conducted in 2017 in the Komi Republic in northern Russia, a region with high rate (26%) of primary multidrug-resistant (MDR) TB. MDR was detected in 30.8% (40/130) isolates; eight were extensively drug resistant. The Beijing genotype was predominant (56.2%). The main Beijing subtypes B0/W148 and 94-32 differed in the MDR rate, 83.3% and 27.2%, respectively. The non-Beijing isolates represented five genotypes (LAM, Ural, Haarlem, X, T). The proportion of Beijing B0/W148 in the "camp" cities (originated from Gulag camps) was twice as large as in other districts of the Komi Republic. To conclude, сirculation of the MDR-associated Beijing B0/W148 cluster critically influences the current situation with MDR-TB in this Russian region. The increased prevalence of B0/W148 in the urban setting on the whole, and in the "camp cities", in particular, indirectly points to the increased transmission capacity of this successful Russian strain of M. tuberculosis.

Trends of Two Epidemic Multidrug-Resistant Strains of Mycobacterium tuberculosis in Argentina Disclosed by Tailored Molecular Strategy

Two Mycobacterium tuberculosis strains-M (sublineage 4.1) and Ra (sublineage 4.3)-have long prevailed in Argentina among patients with multidrug-resistant tuberculosis (MDR-TB). Recently, budget constraints have hampered the surveillance of MDR-TB transmission. Based on whole-genome sequence analysis, we used M- and Ra-specific single nucleotide polymorphisms to tailor two multiplex allele-specific polymerase chain reactions (PCRs), which we applied to 252 stored isolates (95% of all newly diagnosed MDR-TB cases countrywide, 2015-2017). Compared with the latest data available (2007-2009), the M strain has receded (80/324 to 20/252, P < 0.0001), particularly among cross-border migrants (12/58 to 0/53, P = 0.0003) and HIV-infected people (30/97 to 7/74, P = 0.0007), but it still accounts for 4/12 new cases of extensively drug-resistant TB. Differently, the Ra strain remained stable in frequency (39/324 to 33/252) and contributed marginally to the extensive drug-resistance load (1/12). Our novel strategy disclosed recent trends of the two major MDR-TB strains, providing meaningful data to allocate control interventions more efficiently.

Metabolic Changes of Mycobacterium tuberculosis during the Anti-Tuberculosis Therapy

Tuberculosis, caused by Mycobacterium tuberculosis complex bacteria, remains one of the most pressing health problems. Despite the general trend towards reduction of the disease incidence rate, the situation remains extremely tense due to the distribution of the resistant forms. Most often, these strains emerge through the intra-host microevolution of the pathogen during treatment failure. In the present study, the focus was on three serial clinical isolates of Mycobacterium tuberculosis Beijing B0/W148 cluster from one patient with pulmonary tuberculosis, to evaluate their changes in metabolism during anti-tuberculosis therapy. Using whole genome sequencing (WGS), 9 polymorphisms were determined, which occurred in a stepwise or transient manner during treatment and were linked to the resistance (GyrA D94A; inhA t-8a) or virulence. The effect of the inhA t-8a mutation was confirmed on both proteomic and transcriptomic levels. Additionally, the amount of RpsL protein, which is a target of anti-tuberculosis drugs, was reduced. At the systemic level, profound changes in metabolism, linked to the evolution of the pathogen in the host and the effects of therapy, were documented. An overabundance of the FAS-II system proteins (HtdX, HtdY) and expression changes in the virulence factors have been observed at the RNA and protein levels.

Simple Assay for Detection of the Central Asia Outbreak Clade of the Mycobacterium tuberculosis Beijing Genotype

The Central Asia outbreak (CAO) clade is a branch of the Mycobacterium tuberculosis Beijing genotype that is associated with multidrug resistance, increased transmissibility, and epidemic spread in parts of the former Soviet Union. Furthermore, migration flows bring these strains far beyond their areas of origin. We aimed to find a specific molecular marker of the Beijing CAO clade and develop a simple and affordable method for its detection. Based on the bioinformatics analysis of the large M. tuberculosis whole-genome sequencing (WGS) data set (n = 1,398), we identified an IS6110 insertion in the Rv1359-Rv1360 intergenic region as a specific molecular marker of the CAO clade. We further designed and optimized a multiplex PCR method to detect this insertion. The method was validated in silico with the recently published WGS data set from Central Asia (n = 277) and experimentally with M. tuberculosis isolates from European and Asian parts of Russia, the former Soviet Union, and East Asia (n = 319). The developed molecular assay may be recommended for rapid screening of retrospective collections and for prospective surveillance when comprehensive but expensive WGS is not available or practical. The assay may be especially useful in high multidrug-resistant tuberculosis (MDR-TB) burden countries of the former Soviet Union and in countries with respective immigrant communities.

The Evolution of Genotyping Strategies To Detect, Analyze, and Control Transmission of Tuberculosis

The introduction of genotypic tools to analyze Mycobacterium tuberculosis isolates has transformed our knowledge of the transmission dynamics of this pathogen. We discuss the development of the laboratory methods that have been applied in recent years to study the epidemiology of M. tuberculosis. This review integrates two approaches: on the one hand, it considers how genotyping techniques have evolved over the years; and on the other, it looks at how the way we think these techniques should be applied has changed. We begin by examining the application of fingerprinting tools to suspected outbreaks only, before moving on to universal genotyping schemes, and finally we describe the latest real-time strategies used in molecular epidemiology. We also analyze refined approaches to obtaining epidemiological data from patients and to increasing the discriminatory power of genotyping by techniques based on genomic characterization. Finally, we review the development of integrative solutions to reconcile the speed of PCR-based methods with the high discriminatory power of whole-genome sequencing in easily implemented formats adapted to low-resource settings. Our analysis of future considerations highlights the need to bring together the three key elements of high-quality surveillance of transmission in tuberculosis, namely, speed, precision, and ease of implementation.

Early ancient sublineages of Mycobacterium tuberculosis Beijing genotype: unexpected clues from phylogenomics of the pathogen and human history

OBJECTIVE

The Mycobacterium tuberculosis Beijing family is an epidemiologically important lineage subdivided into large-scale phylogenetic sublineages: ancient, endemic in East Asia, and global modern. Here, we analysed ancient sublineages of the Beijing genotype in the Omsk region of southwestern Siberia, an intriguing area at the intersection of European Russia, Siberia, and Central Asia.

METHODS

The study included 423 M. tuberculosis strains isolated in 2013-2017 and subjected to drug susceptibility testing, genotyping, and whole genome sequencing.

RESULTS

The Beijing genotype constituted 280 out of 423 strains. Forty Beijing strains belonged to the early ancient sublineage (wild type mutT4-48). Of these, 11 belonged to the 14717-15 MIRU-VNTR cluster and had intact RD181, 29 belonged to the 1071-32 cluster and had the RD181 deletion. Thirty-nine ancient strains were multidrug-resistant (MDR) and 20 pre-extensively drug resistant (XDR)/XDR. Comparison with global data demonstrated that these clones circulate mainly in Asian Russia with certain phylogenetic affinity to strains from Japan, Korea, and northeastern China. The genome-wide analysis revealed 29-37 single nucleotide polymorphism distances between isolates from different Russian regions within these two clusters.

CONCLUSIONS

Based on phylogenetic, phylogeographic, genomic, and historical data, we hypothesize that these two clones or their direct ancestors were probably brought to Russia ∼70 years ago after the Second World War with Japanese prisoners of war and, until recently, were mainly circulating in Siberia and the Far East. Their elevated prevalence in Omsk along with the extremely strong association with not only MDR but also pre-XDR/XDR also observed in other locations highlight their epidemic potential and the need for monitoring and attention from health authorities.

Major genotype families and epidemic clones of Mycobacterium tuberculosis in Omsk region, Western Siberia, Russia, marked by a high burden of tuberculosis-HIV coinfection

This population-based study characterized Mycobacterium tuberculosis isolates from HIV-positive and HIV-negative tuberculosis (TB) patients in the Omsk region in Western Siberia, Russia. We sought to gain insight into the major genotype families and epidemic and endemic clones of M. tuberculosis in the area with a high burden and adverse trend of TB/HIV coinfection. The study collection included M. tuberculosis isolates from 207 newly-diagnosed patients with pulmonary TB; 55 (26.5%) of patients were HIV-infected. The M. tuberculosis isolates were subjected to drug susceptibility testing and molecular typing based on spoligotyping and analysis of the robust genotype and cluster-specific markers. Patients with disseminated TB disease were more prevalent in the HIV-positive (34.5%) than in the HIV-negative group (4.6%) (P < .001). The Beijing genotype was predominant (62.3% of isolates), and its major subtypes were 94-32-cluster (Central Asian/Russian strain, n = 80) and B0/W148-cluster (successful Russian strain, n = 28). The main non-Beijing families were represented by Latin-American Mediterranean (14.5%), T family (11.1%), Ural (5.8%), and Haarlem (3.9%). Under multivariate logistic regression analysis, MDR was associated with Beijing genotype and not associated with HIV coinfection status (P < .001). Beijing genotype isolates were found more frequently in TB/HIV patients than in TB HIV-negative patients (74.5% versus 57.9%, respectively; P = .031). The non-Beijing genotypes were mainly drug susceptible except for the drug-resistant Ural SIT262 isolates. To summarize, the alarming situation in the Omsk region in Siberia regarding TB/HIV coinfection is seriously influenced by the active circulation of M. tuberculosis isolates of MDR-associated Beijing genotype. Among the non-Beijing families, emergence of the drug-resistant Ural family strains of spoligotype SIT262 warrants attention.

A novel strategy based on genomics and specific PCR reveals how a multidrug-resistant Mycobacterium tuberculosis strain became prevalent in Equatorial Guinea 15 years after its emergence

OBJECTIVE

Molecular epidemiology techniques in tuberculosis (TB) can identify high-risk strains that are actively transmitted. We aimed to implement a novel strategy to optimize the identification and control of multidrug-resistant (MDR) TB in a specific population.

METHODS

We developed a strain-specific PCR tailored from whole genome sequencing (WGS) data to track a specific MDR prevalent strain in Equatorial Guinea (EG-MDR).

RESULTS

The PCR was applied prospectively on remnants of GeneXpert reaction mixtures owing to the lack of culture facilities in Equatorial Guinea. In 147 (93%) of 158 cases, we were able to differentiate between infection by the EG-MDR strain or by any other strain and found that 44% of all rifampicin-resistant TB cases were infected by EG-MDR. We also analysed 93 isolates obtained from Equatorial Guinea 15 years ago, before MDR-TB had become the problem it is today. We found that two of the scarce historical MDR cases were infected by EG-MDR. WGS revealed low variability-six single nucleotide polymorphisms acquired by this strain over 15 years-likely because of the lack in the country of a specific program to treat MDR-TB.

CONCLUSIONS

Our novel strategy, which integrated WGS analysis and strain-specific PCRs, represents a low-cost, rapid and transferable strategy that allowed a prospective efficient survey and fast historical analysis of MDR-TB in a population.

Ultrafast Assessment of the Presence of a High-Risk Mycobacterium tuberculosis Strain in a Population

A persistent 8-year infection by a Beijing Mycobacterium tuberculosis strain from a previous outbreak after importation from West Africa obliged us to investigate secondary cases. We developed a multiplex PCR method based on whole-genome sequencing to target strain-specific single nucleotide polymorphisms (SNPs). In 1 week, we analyzed 868 isolates stored over 6 years. Only 2 cases (immigrants from Guinea Conakry) harbored the strain, which ruled out transmission-despite opportunities-and challenged some of the advantages associated with Beijing strains.

Application of Deletion- Targeted Multiplex PCR technique for detection of Mycobacterium tuberculosis Beijing strains in samples from tuberculosis patients

BACKGROUND AND OBJECTIVE

Molecular epidemiological studies have shown that certain genotypes of Mycobacterium tuberculosis (MTB) are over-represented in limited geographical regions, suggesting of evolution of certain genotypes with increasing virulence and pathogenicity. Beijing strain of MTB was initially described by its potential to cause outbreaks worldwide and its association with drug resistance. Due to tuberculosis (TB)-related mortality which is associated with Beijing genotype, this study was designed with the aim to detect the MTB Beijing genotype in the region of study.

MATERIALS AND METHODS

A total of 170 clinical isolates of MTB were collected from the TB reference laboratory of Khuzestan province, Iran, over one year period from February 2010 to February 2011. Phenotypic tests were used for preliminary detection of MTB. Culture positive MTB isolates were confirmed by multiplex PCR based on IS6110 gene with subsequent screening for resistance to isoniazid (INH), and rifampin (RIF) by PCR using relevant primers. Three set of primers were used to differentiate Beijing from non-Beijing strains by using Deletion- Targeted Multiplex (DTM) PCR.

RESULTS

From 160 PCR-confirmed MTB isolates, 18 (11.25%) showed mutation in katG gene related to INH resistance and 20 (12.5%), associated with mutation in rpoB gene related to RIF resistance, and 8 (5%) were detected as Beijing strain using multiplex PCR. The majority of detected Beijing strains (6/8[75%]) comprised mutation in katG gene with the prevalent mutation specifically in codon 315. In 4 Beijing strains (2.5%), mutation in rpoB gene were also detected.

CONCLUSION

Using DTM- PCR, the rate of Beijing strains in the region of study was determined as 5%. Although for detection of MTB antimicrobial resistance, it is advised to use a combination of conventional antimicrobial susceptibility testing and molecular techniques, however for time saving, it seems that DTM-PCR, is a simple technique for use in areas of the world where Beijing strains are highly prevalent.