Molecular epidemiological analysis of Mycobacterium tuberculosis isolates from rural population of nationwide tuberculosis prevalence survey in Mongolia

We investigated the prevalence, trends, and risk factors for pyrazinamide (PZA) and moxifloxacin (MOX) resistance among tuberculosis (TB) cases in China and also analyzed the population structure of Mycobacterium tuberculosis strains. All the M. tuberculosis strains enrolled in this study were collected from the national TB prevalence surveys. Each strain was genotyped by analyzing the regions of RD105 and IS6110 in the NTF region. The Bactec MGIT 960 system was used to detect the drug susceptibility of M. tuberculosis isolates to PZA and MOX. Based on the genotyping results, 241 (66.4%) strains were classified as Beijing genotype in 2000, which was significantly lower than in 2010 (76.2%, P < 0.01). The proportion of the modern Beijing genotype increased significantly from 49.6% in 2000 to 68.1% in 2010 (P < 0.01), while no significant difference was observed in the rate of ancient Beijing genotype between 2000 and 2010 (P = 0.676). In addition, we found that the proportion of PZA resistance in 2010 (15.0%) was significantly higher than that in 2000 (9.6%, P = 0.04). For MOX, there were more MOX-resistant isolates detected in 2010 (7.7%) than in 2000 (3.0%). In conclusion, our data demonstrate that the Beijing genotype was the predominant M. tuberculosis lineage during the past decade. The proportion of Beijing genotype isolates significantly increased from 2000 to 2010, largely due to an increase in the modern Beijing sublineage. In addition, resistance to PZA and MOX increased significantly in China between 2000 and 2010.

To the Editor: Described as a “template for success” by Hanekom et al. [1] the Beijing genotype of Mycobacterium tuberculosis has been associated with hypervirulence, drug resistance, evasion of the bacille Calmette–Guerin (BCG) vaccine and differential immunoregulation [1]. The genotype is itself diverse; accordingly the fact that specific traits have been associated with Beijing only in certain settings may be explained by the variation in the subtypes that predominate in each. We sought to explore the role that the Beijing genotype plays in the epidemiology of multidrug-resistant (MDR) tuberculosis (TB) in two very different epidemiological settings: England and Peru. In the UK nearly three quarters of TB disease occurs amongst migrants, which may result from latent M. tuberculosis infections acquired from high-burden countries of origin. Thus the distribution of lineages in the UK reflects a composite of the circulating strains in other nations. Whilst increasing levels of MDR-TB in the UK have triggered understandable concern, only a small fraction of cases of TB are MDR (in 2011 this was 1.0%) [2]. In contrast, the Peruvian TB epidemic is relatively “home-grown” and the prevalence of drug resistance is greater (in 2011 5.3% were MDR-TB) [2]. Our objectives were thus: 1) identify any association between the Beijing genotype and MDR in these two settings, and 2) to examine if trends in Beijing might explain changes in the prevalence of MDR-TB over time. Four datasets were used during this study: two English studies and two Peruvian studies. The English datasets were taken from Public Health England's Enhanced Tuberculosis Surveillance System and Mycobacterial Surveillance Network and were referred to as England 1 and England 2. England 1 consisted of 8 859 individuals diagnosed and 24-loci MIRU-VNTR (mycobacterial interspersed repetitive units variable number tandem repeats) strain-typed …

Globally, an estimated one-million new tuberculosis (TB) cases occurred in children in 2014. For a long time, research of TB in children has been neglected. Most research and surveillance of TB is performed in adults, and the resulting lack of evidence in children is a major barrier for implementation of rational control strategies for children, including diagnosis. More research on TB in children is of importance as children are more susceptible to developing severe extrapulmonary TB, children require different approaches to both diagnosis and treatment and paediatric TB reflects the ongoing transmission of TB in the population. This research gap on the epidemiology of tuberculosis in children, especially in high burden countries, should be addressed in order to better understand the dynamics of TB transmission in both adults and children. Accurate data are the basis for establishment of effective control strategies. This thesis aims to assess the diagnostic role of microscopic observation drug susceptibility (MODS) and mycobacterial blood culture for diagnosis of TB in children as well as to present the epidemiological characteristics of paediatric TB in northern Vietnam with regard to drug resistance and genotypes of Mycobacterium tuberculosis (MTB), the causative agent of TB, isolated from them. MODS is a low cost non-commercial liquid culture assay to detect MTB by microscopy. MODS was compared with conventional assays including Ziehl-Neelsen smear (ZN) and Lowenstein-Jensen culture (LJ) in a study conducted from 2009 to 2010 at the National Hospital for Paediatrics, a general paediatric hospital, in Hanoi, Vietnam. In suspected paediatric TB cases, the MODS test was shown to be significantly more sensitive than both smear (46.0% vs. 8.8%) and LJ (46.0% vs. 38.9%), and significantly faster than LJ with a median time difference of 28 days in favour of MODS (7 days vs. 35 days). The findings suggest that MODS is a rapid low-cost diagnostic tool for TB diagnosis in the paediatric population. The additional yield of mycobacterial blood culture was assessed in comparison to routine detection methods for TB diagnosis in children in two hospitals in Vietnam. The findings show that mycobacterial blood culture detected an additional six TB cases of which 5 cases were negative with other tests and in the remaining case no other tests were done. All six cases were susceptible to rifampicin and isoniazid. The overall performance of TB blood culture was poor as compared to routine culture with regard to detection rate (2.9%, 16/554 vs. 16.6%, 92/554) and turnaround time (26 days vs. 14 days). The incremental cost for adding one additional TB case is substantial. Therefore, addition of mycobacterial blood culture into routine diagnostics has limited utility in resource limited settings. To assess the molecular epidemiology of paediatric TB in northern Vietnam, a collection of 125 MTB isolates from children with TB admitted to NHP during 2009 to 2013 was analysed. Drug susceptibility testing results from 121 isolates and genotypes from 120 isolates were generated. The phenotypic drug susceptibility testing showed that 20.7% was resistant to isoniazid (25/121), 3.3% resistant to rifampicin (4/121), 28.1% resistant to streptomycin (34/121) and 2.5% resistant to ethambutol (1/121). There were 4 cases with multidrug resistant TB. The high frequency of resistance to isoniazid and streptomycin are consistent with data from adults in Vietnam, suggesting the ongoing transmission of drug resistant MTB in the community. MIRU typing patterns showed that the Beijing genotype was predominant in this population (63.3%, 76/120), which is in agreement with various prior studies in adults in Vietnam. These findings provide more evidence to support the hypothesis of the epidemic spread of the Beijing genotype in Vietnam. In this study, an association between Beijing genotype and drug resistance to streptomycin and isoniazid was observed. The number of MDR isolates was too small to draw conclusions regarding association of MDR and Beijing genotype. Collectively, these results demonstrate that liquid culture can improve the yield of TB diagnosis in Vietnam and mycobacterial blood culture should not be routinely performed for paediatric cases. The molecular epidemiology study also showed that the Beijing genotype is the predominant lineage among actively transmitted strains in Vietnam and that it is associated with both isoniazid and streptomycin resistance. Paediatric TB remains a significant cause of morbidity and mortality in Vietnamese children and sustained political and social commitment from all stakeholders, including governments, funders, academics and the medical community will be needed to improve diagnosis, treatment and prevention of TB in children globally.

BackgroundIn the last decades, the molecular epidemiological investigation of Mycobacterium tuberculosis has significantly increased our understanding of tuberculosis epidemiology. However, few such studies have been done in southern Xinjiang, China. We aimed to clarify the molecular epidemic characteristics and their association with drug resistance in the M. tuberculosis isolates circulating in this area.MethodsA total of 347 isolates obtained from southern Xinjiang, China between Sep, 2017 and Sep, 2019 were included to characterize using a 15-locus MIRU-VNTR (VNTR-15China) typing and spoligotyping, and test for drug susceptibility profiles. Then the lineages and clustering of the isolates were analyzed, as well as their association with drug resistance.ResultsSpoligotyping results showed that 60 spoligotype international types (SITs) containing 35 predefined SITs and 25 Orphan or New patterns, and 12 definite genotypes were found, and the top three prevalent genotypes were Beijing genotype (207, 59.7%), followed by CAS1-Delhi (46, 13.6%), and Ural-2 (30, 8.6%). The prevalence of Beijing genotype infection in the younger age group (≤30) was more frequent than the two older groups (30~59 and ≥60 years old, both P values <0.05). The Beijing genotype showed significantly higher prevalence of resistance to isoniazid, rifampicin, ethambutol, multi-drug or at least one drug than the non-Beijing genotype (All P values ≤0.05). The estimated proportion of tuberculosis cases due to transmission was 18.4% according to the cluster rate acquired by VNTR-15China typing, and the Beijing genotype was the risk factor for the clustering (OR 9.15, 95% CI: 4.18–20.05).ConclusionOur data demonstrated that the Beijing genotype is the dominant lineage, associated with drug resistance, and was more likely to infect young people and contributed to tuberculosis transmission in southern Xinjiang, China. These findings will contribute to a better understanding of tuberculosis epidemiology in this area.

Long-term outcomes of patients with extensively drug-resistant tuberculosis in South Africa: a cohort study

ABSTRACTLineage 2 (East Asian), which includes the Beijing genotype, is one of the most prevalent lineages of Mycobacterium tuberculosis (Mtb) throughout the world. The Beijing family is associated to hypervirulence and drug-resistant tuberculosis. The study of this genotype’s circulation in Latin America is crucial for achieving total control of TB, the goal established by the World Health Organization, for the American sub-continent, before 2035. In this sense, the present work presents an overview of the status of the Beijing genotype for this region, with a bibliographical review, and data analysis of MIRU-VNTRs for available Beijing isolates. Certain countries present a prevalent trend of <5%, suggesting low transmissibility for the region, with the exception of Cuba (17.2%), Perú (16%) and Colombia (5%). Minimum Spanning Tree analysis, obtained from MIRU-VNTR data, shows distribution of specific clonal complex strains in each country. From this data, in most countries, we found that molecular epidemiology has not been a tool used for the control of TB, suggesting that the Beijing genotype may be underestimated in Latin America. It is recommended that countries with the highest incidence of the Beijing genotype use effective control strategies and increased care, as a requirement for public health systems.

Identifying eligible individuals for a prevalence survey is difficult in the absence of a disease register or a national population register. To develop a method to identify and invite eligible individuals to participate in a national prevalence survey while maintaining confidentiality and complying with privacy legislation. A unique identifier (based on date of birth, sex and initials) was developed so that database holders could identify eligible individuals, notify us and invite them on our behalf to participate in a national multiple sclerosis prevalence survey while maintaining confidentiality and complying with privacy legislation. Several organisations (including central government, health and non-governmental organisations) used the method described to assign unique identifiers to individuals listed on their databases and to forward invitations and consent forms to them. The use of a unique identifier allowed us to recognise and record all the sources of identification for each individual. This prevented double counting or approaching the same individual more than once and facilitated the use of capture-recapture methods to improve the prevalence estimate. Capture-recapture analysis estimated that the method identified over 96% of eligible individuals in this prevalence survey. This method was developed and used successfully in a national prevalence survey of multiple sclerosis in New Zealand. The method may be useful for prevalence surveys of other diseases in New Zealand and for prevalence surveys in other countries with similar privacy legislation and lack of disease registers and population registers.

To assess the epidemiological impact of mass tuberculosis (TB) screening in the community and the prognosis of bacteriologically negative individuals with abnormal findings on chest radiography (CXR). A follow-up study consisting of two parts--a register match of notified TB cases with 22,160 participants in a national TB prevalence survey, and a repeat medical examination for the subjects of a prevalence survey with abnormal findings on CXR--was conducted 2 years after the prevalence survey in Cambodia. Thirty-four cases with new smear-positive TB were detected by register match, giving a standardised notification ratio of 0.38 (95%CI 0.27-0.52). An additional seven new smear-positive TB cases and 93 new smear-negative, culture-positive TB cases were detected by medical examination. The incidence rates of bacteriologically positive TB were 8.5% per year (95%CI 6.3-11.2) in cases with a CXR suggestive of active TB and 2.9% per year (95%CI 2.2-3.7) in those with a CXR with other abnormalities. Detection and treatment of smear-negative, culture-positive TB cases as well as smear-positive TB cases was associated with a rapid reduction in subsequent incidence of new smear-positive TB. Sputum culture-negative individuals with abnormal CXR findings are at a high risk of disease progression, and require follow-up and potentially preventive treatment.

Viruses of HIV-1-infected individuals whose transmission is related group phylogenetically in transmission clusters (TCs). The study of the phylogenetic relations of these viruses and the factors associated with these individuals is essential to analyze the HIV-1 epidemic. In this study, we examine the role of TCs in the epidemiology of HIV-1 infection in Galicia and the Basque County, two regions of northern Spain. A total of 1,158 HIV-1-infected patients from both regions with new diagnoses (NDs) in 2013–2018 were included in the study. Partial HIV-1 pol sequences were analyzed phylogenetically by approximately maximum-likelihood with FastTree 2. In this analysis, 10,687 additional sequences from samples from HIV-1-infected individuals collected in Spain in 1999–2019 were also included to assign TC membership and to determine TCs’ sizes. TCs were defined as those which included viruses from ≥4 individuals, at least 50% of them Spaniards, and with ≥0.95 Shimodaira-Hasegawa-like node support in the phylogenetic tree. Factors associated to TCs were evaluated using odds ratios (OR) and their 95% CI. Fifty-one percent of NDs grouped in 162 TCs. Male patients (OR: 2.6; 95% CI: 1.5–4.7) and men having sex with men (MSM; OR: 2.1; 95% CI: 1.4–3.2) had higher odds of belonging to a TC compared to female and heterosexual patients, respectively. Individuals from Latin America (OR: 0.3; 95% CI: 0.2–0.4), North Africa (OR: 0.4; 95% CI: 0.2–1.0), and especially Sub-Saharan Africa (OR: 0.02; 95% CI: 0.003–0.2) were inversely associated to belonging to TCs compared to native Spaniards. Our results show that TCs are important components of the HIV-1 epidemics in the two Spanish regions studied, where transmission between MSM is predominant. The majority of migrants were infected with viruses not belonging to TCs that expand in Spain. Molecular epidemiology is essential to identify local peculiarities of HIV-1 propagation. The early detection of TCs and prevention of their expansion, implementing effective control measures, could reduce HIV-1 infections.

Russia is a TB high-burden country with steadily increasing MDR-TB rate (30% among new cases). We aimed to analyze the genetic structure of the clinically and epidemiologically significant subtypes of ancient and modern sublineages of the <i>M. tuberculosis</i> Beijing genotype in different regions of Russia. M. tuberculosis clinical isolates (n=1042) from Russian regions (Northwest, Ural, Siberia, Far East) were tested by genotyping and analysis of subtype/sublineage specific markers of the Beijing genotype. The Beijing genotype was dominant in all studied regions (50-72%), and was associated with MDR compared to non-Beijing genotypes (p=0.0003). The Beijing 94-32-cluster (=Central-Asian/Russian clade) was overall dominant (21-48%), but was significantly less MDR than Beijing B0/W148-cluster (=Russian epidemic clone) (p=0.02). The highest rate of the 94-32-cluster in Omsk, West Siberia may be due to its proximity to Kazakhstan. B0/W148 predominates in Siberia (up to 70%), its likely region of origin. The Beijing early ancient sublineage 2 (del_RD181) is mainly found in European Russia and Siberia, while early ancient sublineage 1 (intact RD181) dominates in Buryatia, Far East, at 16%. Noteworthy, both major VNTR clusters within ancient Beijing were strongly associated with MDR and XDR. To conclude, highly drug-resistant and genetically diverse strains of the <i>M. tuberculosis</i> Beijing genotype circulate in different regions of Russia and new resistant clones appear emerging. This emphasizes the importance of their permanent monitoring that is critical for timely tracing of spread and emergence of new resistant variants. Supported by Russian Science Foundation (grant 19-14-00013).

Northern Russia is characterized by socio-environmental conditions contributing to the spread of tuberculosis (TB) and a high ~30% rate of primary multidrug-resistant (MDR) TB. We applied high-resolution molecular methods to study the Mycobacterium tuberculosis population in the Arkhangelsk region of Northern Russia. All available M. tuberculosis isolates recovered from newly diagnosed patients from January to December 2018 (n = 88) were genotyped using 24-loci MIRU-VNTR, spoligotyping, and, partly, by whole-genome sequencing (WGS). The population structure revealed a predominance of the Beijing genotype and Euro-American lineage, with significant drug resistance burden associated with Beijing and its B0/W148 strain. Beijing strains showed a significantly higher association with MDR and pre-extensively drug-resistant (pre-XDR) TB compared to non-Beijing strains (P = 0.0013). All Beijing B0/W148 isolates were MDR, whereas the majority (71.4%) of Beijing Central Asian/Russian subtype strains were drug-sensitive. WGS analysis of newly discovered Beijing clusters 3828-32 and 10167-32 in this area indicated a historical transmission over several decades, reflecting long-term endemic circulation. The presence of compensatory mutations in rpoC among MDR strains suggests enhanced fitness facilitating their ongoing transmission. An intriguing cluster of recent transmission of a non-Beijing strain (spoligotype SIT53, L4.8 sublineage) was identified through combined epidemiological and genomic investigation. To conclude, the prevalence of Beijing strains rose from 39.3% in 1998 to 67.0% (P < 0.001), and Russian epidemic MDR strain B0/W148 increased its rate from 11.2% in 1998 to 20.5% (P = 0.097). This highlights the key role of MDR Beijing strains, including new resistant clusters, in disseminating MDR-TB in the region and the importance of continuous surveillance using high-resolution genotyping.IMPORTANCEThe Arkhangelsk region is the largest province of northern European Russia. One-third of newly diagnosed tuberculosis patients are infected with multidrug-resistant (MDR) Mycobacterium tuberculosis strains. We assessed the molecular population structure of M. tuberculosis in the Arkhangelsk region in the COVID-19 pre-pandemic year 2018. We identified important MDR clusters and elucidated tuberculosis transmission patterns. An intriguing cluster of recent transmission was identified through the combined use of epidemiological investigation and whole-genome sequencing. The prevalence of Beijing genotype strains increased from 39.3% in 1998 to 67.0%, and the Russian epidemic MDR strain B0/W148 doubled from 11.2% in 1998 to 20.5%. Furthermore, we described new MDR clusters emerging within the Beijing genotype. This highlights the key impact of the MDR Beijing strains and the importance of continuous surveillance using high-resolution genotyping. This study of the pre-pandemic strain collection provides an indispensable intermediate time point between earlier studies carried out 25 years ago and ongoing surveillance.

Mycobacterium tuberculosis (Mtb) inhibits dendritric cells (DC) function in order to delay T cell response. Furthermore, there is increasing evidence that genetic diversity of Mtb strains can affect their interaction with the immune system. Beijing genotype has attracted attention because of its high prevalence and multi-drug resistance. Although it is known that this genotype is hypervirulent and differentially activates macrophages when compared to other genotypes, little is known about its interaction with DC. In order to address this issue, murine bone marrow derived DC (BMDC) were stimulated with soluble extracts (SE) from BCG, H37Rv, Canetti and Beijing genotypes. We observed that unlike other mycobacteria strains, SE-Beijing was unable to induce maturation of DC as assessed by cell surface MHC-II expression. DC stimulated with SE-Beijing failed to produce IL-12 and TNF-α, but did secrete IL-10. Interestingly, SE-Beijing induced CCR7 and PDL-1 on BMDC, but did not induce the expression of CD86. When BMDC stimulated with SE-Beijing were used to activate CD4+ cells they were unable to induce a Th1 response when compared with less virulent genotypes. These results indicate that Beijing is able to modulate DC activation and function, which may be related to the pathogenesis induced by this genotype.

BackgroundMultidrug-resistant tuberculosis (MDR-TB) isolates collected from Fujian province, China were assessed for molecular epidemiological characteristics. Analysis of isolate genotype profiles revealed that the Beijing genotype was associated with especially high drug resistance and community transmission rates.MethodsA total of 119 MDR-TB isolates obtained from TB patients in Fujian province were typed using 24–locus mycobacterium interspersed repetitive unit-variable number tandem repeat (MIRU-VNTR) typing and spoligotyping. Drug susceptibility testing of all isolates was conducted using the L-J proportion method, with pyrazinamide (PZA) susceptibility testing conducted using the Mycobacterium Growth Indicator Tube System 960 (MGIT 960).ResultsWe obtained 26 spoligotypes for the 119 isolates examined in this work. Spoligotyping results revealed that 80 (67.2%) isolates possessed the Beijing family genotypic profiles. Patients aged 25–44 years and ≥45 years were most likely to be infected by non-Beijing genotypes. The percentage of clustered cases with both PZA and ofloxacin (OFLX) resistance was significantly greater than the corresponding percentage for non-clustered cases. Of 44 PZA-resistant isolates, 28 isolates (63.6%) harbored pncA mutations, while pncA mutations were only detected in 7 (9.3%) PZA-susceptible isolates.ConclusionOur data demonstrate that the Beijing genotype is the dominant lineage among MDR-TB strains circulating in Fujian. Thus, MDR-TB infections occurring within this province are not likely associated with recent transmission events. PZA and fluoroquinolone resistance profiles were found to be associated with clustered isolates. Mutation of pncA is the main driver of MDR-TB PZA resistance and is associated with mutation sites scattered throughout the entire pncA protein-coding region.

College students are a crucial link in curbing the epidemic. The aim of this study is to analyze the genetic diversity and drug resistance of Mycobacterium tuberculosis strains in college students with tuberculosis in Beijing, revealing the lineage structure and transmission patterns specific to this group. This study used the hospital's electronic management system to screen for tuberculosis among college students in Changping District, Beijing, from January 2004 to December 2023. Socio-demographic and clinical data were collected, and whole-genome sequencing was performed on culture-positive isolates. Isolates with a genetic distance of less than 12 SNPs were grouped into the same genomic cluster. The TB Profiler software predicted drug resistance mutations, and categorical data were analyzed using Chi-square or Fisher's exact tests. Among the 1436 college students with tuberculosis, a total of 153 isolates successfully underwent whole-genome sequencing. The results showed that about one-third (49/153) of the isolates carried one or more drug resistance genes, with more than half (26/49) associated with first-line anti-tuberculosis drugs. However, encouragingly, the incidence of drug-resistant tuberculosis showed a significant downward trend, with statistical significance (p<0.05). Lineage 2 (86.3%, 132/153) was the predominant genotype, with the Beijing genotype (90.1%, 120/153) being the most common, while the isolation of Lineage 3 in a student from Xinjiang. Sixteen college student isolates clustered, and all of which were Beijing genotype. Transmission within the same campus showed characteristics of short clustering time. The drug resistance rate among college students is relatively high, however it shows a declining trend. School tuberculosis infections could stem not only from within-campus transmission but also necessitate consideration of spatial and cross-regional spread possibilities.

Ethambutol (EMB) is one of the first-line drugs used in the standard combination therapy for tuberculosis (TB) caused by Mycobacterium tuberculosis complex (MTC), and resistance to drugs that play a key role in treatment is increasing worldwide. Mutations in the embCAB operon that have been confirmed to be associated with resistance are responsible for EMB resistance. In this study, it was aimed to determine the frequency and patterns of mutations in embA, embB and embC gene regions in clinical MTC isolates found to be phenotypically resistant and susceptible to EMB. A total of 64 MTC isolates, 44 of resistant to EMB and 20 of susceptible to EMB, isoniazid, rifampicin, and streptomycin by conventional phenotypic drug susceptibility test, were included in the study. Following the DNA isolation, embA, embB and embC gene regions associated with EMB resistance were amplified with specific primer sequences. The PCR products were cycle sequenced using the Bigdye Terminator v3.1 Cycle Sequencing kit (Applied Biosystems, USA) and electrophoretically separated on the ABI PRISM 3130XL Genetic Analyzer (Applied Biosystems, USA). Mutated gene regions were identified by aligning sequence analysis data in multiple sequence analysis programs. In the study, genomic mutations in the embCAB operon were detected in 68.2% (30/44) of the EMB resistant isolates. Mutations in the embB gene region were detected in 66% (29/44) of the resistant isolates, 76% (22/29) of these mutations were at codon 306 and the most common mutation patterns in this codon were determined as ATG→GTG (M306V; 58.6%; 17/29), ATG→ATA, ATC or ATT (M306I; 17.2%; 5/29). Other mutations in the embB gene region were determined as Y334H (3.4%; 1/29), D354A (6.9%; 2/29), E378A (3.4%; 1/29), G406C (3.4%; 1/29), M423I (3.4%; 1/29) and E521A (3.4%; 1/29). Of the 44 EMB-resistant isolates, mutations were detected in one (2.3%) of the isolate in the embA gene region (L330L) and in two (4.5%) of the isolates in the embC gene region (T270I in one isolate and T270I and E305E in the other isolate). Of the phenotypically EMB susceptible isolates, mutation was detected in only one (5%) of the isolates in the embA gene region (E180G). In our study, it was determined that mutations frequently occur in codon 306 of the embB gene in EMB-resistant MTC isolates and this mutation has a potential role in the development of EMB resistance. However, it was concluded that the absence of mutations does not exclude phenotypic EMB resistance. Our results will shed light on the molecular epidemiology of embCAB operon mutations that cause EMB resistance in our country.