Drug-resistant tuberculosis in the WHO European Region: An analysis of surveillance data

Global status of phenotypic pyrazinamide resistance in Mycobacterium tuberculosis clinical isolates: an updated systematic review and meta-analysis

Pyrazinamide (PZA) is an essential first-line tuberculosis drug for its unique mechanism of action active against multidrug-resistant-TB (MDR-TB). Thus, the aim of updated meta-analysis was to estimate the PZA weighted pooled resistance (WPR) rate in M. tuberculosis isolates based on publication date and WHO regions. We systematically searched the related reports in PubMed, Scopus, and Embase (from January 2015 to July 2022). Statistical analyses were performed using STATA software. The 115 final reports in the analysis investigated phenotypic PZA resistance data. The WPR of PZA was 57% (95% CI 48-65%) in MDR-TB cases. According to the WHO regions, the higher WPRs of PZA were reported in the Western Pacific (32%; 95% CI 18-46%), South East Asian region (37%; 95% CI 31-43%), and the Eastern Mediterranean (78%; 95% CI 54-95%) among any-TB patients, high risk of MDR-TB patients, and MDR-TB patients, respectively. A negligible increase in the rate of PZA resistance were showed in MDR-TB cases (55% to 58%). The rate of PZA resistance has been rising in recent years among MDR-TB cases, underlines the essential for both standard and novel drug regimens development.

Clinical implications of molecular drug resistance testing for Mycobacterium tuberculosis: a 2023 TBnet/RESIST-TB consensus statement

Drug-resistant tuberculosis is a substantial health-care concern worldwide. Despite culture-based methods being considered the gold standard for drug susceptibility testing, molecular methods provide rapid information about the Mycobacterium tuberculosis mutations associated with resistance to anti-tuberculosis drugs. This consensus document was developed on the basis of a comprehensive literature search, by the TBnet and RESIST-TB networks, about reporting standards for the clinical use of molecular drug susceptibility testing. Review and the search for evidence included hand-searching journals and searching electronic databases. The panel identified studies that linked mutations in genomic regions of M tuberculosis with treatment outcome data. Implementation of molecular testing for the prediction of drug resistance in M tuberculosis is key. Detection of mutations in clinical isolates has implications for the clinical management of patients with multidrug-resistant or rifampicin-resistant tuberculosis, especially in situations when phenotypic drug susceptibility testing is not available. A multidisciplinary team including clinicians, microbiologists, and laboratory scientists reached a consensus on key questions relevant to molecular prediction of drug susceptibility or resistance to M tuberculosis, and their implications for clinical practice. This consensus document should help clinicians in the management of patients with tuberculosis, providing guidance for the design of treatment regimens and optimising outcomes.

Associated risk factor of tuberculosis infection among adult patients in Gedeo Zone, Southern Ethiopia

Background

Tuberculosis remains a major global health problem causing death among millions of people each year. Even though many of the World Health Organization recommended tuberculosis control strategies were implemented, there is still a major gap in tuberculosis case detection and treatment which resulted in rapid transmission of the cases in high burden countries. This study aimed to provide updated information on the contributing factors for the development of tuberculosis.

Methods

A case-control study was carried out in Gedeo Zone from February to July 2021 to assess the risk factors of tuberculosis. Cases were confirmed pulmonary tuberculosis patients with age ⩾18 years, while controls were participants who were confirmed to be pulmonary tuberculosis negative with the same age. Multivariate logistic regression models were used to assess the associated risk factor.

Results

A total of 368 individuals (173 cases and 173 controls) were included in this study. Based on the multivariable logistic regression analysis, we identified six variables as independent risk factors for the development of tuberculosis after controlling possible confounders. Those were patients with income <1500 Ethiopian birr per month (adjusted odds ratio = 2.35; 95% confidence interval: 1.22-3.97), patients with no educational background (illiterate) (adjusted odds ratio = 2.10; 95% confidence interval: 1.17-2.51), patients smoking cigarette (adjusted odds ratio = 2.89; 95% confidence interval: 2.10-3.82), patients chewing khat (adjusted odds ratio = 2.86; 95% confidence interval: 1.28-3.79), patients in close contact with known tuberculosis cases (adjusted odds ratio = 3.63; 95% confidence interval: 2.24-4.46), and patients being positive for HIV (adjusted odds ratio = 3.01; 95% confidence interval: 1.07-3.52) who were found to be significantly associated with tuberculosis development, while Bacille Calmette-Guérin vaccination had a protective effect against the development of tuberculosis (adjusted odds ratio = 0.52; 95% confidence interval: 0.21-0.88).

Conclusion

The priority should be given to the identified contributing factors through application of coordinated efforts on screening of patients suspected for pulmonary tuberculosis and all contacts of pulmonary tuberculosis patients and treatment of known tuberculosis cases, and appropriate control methods to reduce Mycobacterium tuberculosis cases.

Investigating the Relationship between Knowledge and Hepatotoxic Effects with Medication Adherence of TB Patients in Banyumas Regency, Indonesia

Tuberculosis (TB) still remains the burden in Indonesia. One of the factors that may influence the treatment success of TB is patient's adherence. However, the hepatotoxicity of the TB medicine may decrease the patient's adherence. Our study's aim is to investigate the relationship between the patient's knowledge and the hepatotoxicity with medication adherence of TB patients in Banyumas Regency. This study was conducted at one Community Lung Health Center and two hospitals in Banyumas Regency, Purwokerto, Center of Java, Indonesia. The respondents were 91 TB patients with hepatotoxicity characterized by an increased aspartate transaminase (AST) and alanine aminotransferase (ALT). The level of the patients' knowledge about the hepatotoxicity effect was determined using a questionnaire. The patients' adherence was determined using the Medication Adherence Rating Scale -5 (MARS) questionnaire and pill count methods. Most of the patients were male (53.8%), the age was in the range of 18-29 years old (3.5%), they have no smoking history (59.3%), and their last education majorly was senior high school (46.2%). Most TB patients had poor knowledge (47.3%) and the hepatotoxic effect often appeared in grade 1 (61.5%). The TB patients with a good and moderate level of knowledge were 17.6% and 35.2%, respectively. The TB patients with moderate and severe hepatotoxicity were 39.4% and 1.1%, respectively. The measurement of the level of respondents' adherence using MARS-5 showed that 51.6% of patients had good adherence. We determined the rest of the drug-using pill count method, which resulted in 62.6% of patients adhering to taking antituberculosis drugs. TB patients with a sufficient knowledge and those with mild hepatotoxicity show the higher adherence (p < 0.001). There is a significant relationship between a high level of the patient's knowledge about hepatotoxicity effect, less severity of the hepatotoxic effect, and increased patient adherence in taking the medication.

In vitro activity of bedaquiline against Mycobacterium avium complex

Introduction. Nontuberculous mycobacteria (NTM) are widespread in the environment and can cause various diseases in humans, especially immunocompromised patients.Hypothesis. Treatment of diseases caused by NTM is a complicated issue, mainly due to the resistance of the pathogen to most antimicrobial agents. Bedaquiline (Bdq) is now widely used for the treatment of multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis (TB).Aim. The main goal of our study was to evaluate the activity of Bdq against Mycobacterium avium complex (MAC), the most common species among NTM.Methodology. A total of 166 MAC cultures (124 Mycobacterium avium and 42 Mycobacterium intracellulare) were studied. The minimum inhibitory concentrations (MICs) of Bdq for M. avium and M. intracellulare were obtained by twofold serial dilutions in the Middlebrook 7H9 medium. MIC ranges were determined and the MIC₅₀, MIC₉₀ and ECOFF values were obtained.Results. The MICs in respect of M. avium ranged from 0.003 to 1.0 µg ml^-1; those for M. intracellulare ranged from 0.003 to 0.5 µg ml^-1. The Bdq MIC₅₀ and MIC₉₀ values were found to be 0.015 and 0.12 µg ml^-1 , respectively, for M. avium and 0.007 and 0.06 µg ml^-1, respectively, for M. intracellulare. The tentative ECOFF values for M. avium and M. intracellulare were 0.12 and 0.06 µg ml^-1, respectively.Conclusion. The main bedaquiline susceptibility parameters for MAC strains isolated in the Moscow region were determined.

Drug-resistant tuberculosis in eastern Europe and central Asia: a time-series analysis of routine surveillance data

BACKGROUND

Among all WHO regions, the WHO European Region has the highest proportion of drug-resistant tuberculosis among new and retreated cases. The 18 high-priority countries in eastern Europe and central Asia account for 85% of the tuberculosis incidence and more than 90% of drug-resistant tuberculosis cases emerging in the region. We aimed to analyse time-series trends in notification rates of drug-resistant tuberculosis among new tuberculosis cases in the 18 high-priority countries in the WHO European Region.

METHODS

We used country data stored in WHO's global tuberculosis database. For each country, we calculated annual notification rates per 100 000 population of new tuberculosis cases and of drug-resistant tuberculosis among new cases reported from Jan 1, 2000, to Dec 31, 2017. We computed annual percentage changes of notification rates and identified time-points of significant change in trends using the joinpoint regression method.

FINDINGS

All 17 countries with data (no data available from Turkmenistan) showed a significant decline in new tuberculosis notification rates in the most recent years since the last joinpoint if one was identified. Notification rates of drug-resistant tuberculosis showed diverse trends, with substantial year-to-year variation. In the most recent years, notification rates of drug-resistant tuberculosis among new tuberculosis cases were decreasing in two countries (Estonia and Latvia), increasing in eight countries (Azerbaijan, Kyrgyzstan, Moldova [Republic of Moldova], Romania, Russia [Russian Federation], Tajikistan, Ukraine, and Uzbekistan), and stable in seven countries (Armenia, Belarus, Bulgaria, Georgia, Kazakhstan, Lithuania, and Turkey).

INTERPRETATION

Our findings suggest that countries in the WHO European Region are more successful in controlling drug-susceptible tuberculosis than drug-resistant forms, and as a result, the proportion of drug-resistant strains among newly notified patients with tuberculosis is increasing in many settings. Two countries showed that it is possible to decrease incidence of both drug-susceptible and drug-resistant tuberculosis. If no additional efforts are made in prevention and care of patients with drug-resistant tuberculosis, further decline of the tuberculosis burden will be halted. Further studies are needed to investigate the success stories and document the most effective interventions to reach the target to end tuberculosis by 2030.

FUNDING

United States Agency for International Development.

Resistance To First-Line Antituberculosis Drugs And Prevalence Of pncA Mutations In Clinical Isolates Of Mycobacterium tuberculosis From Zunyi, Guizhou Province Of China

Background

China is one of the high-burden countries for multidrug-resistant tuberculosis (MDR-TB), and pyrazinamide is one of the anti-TB drugs used for the shorter MDR-TB treatment regimen. The aim of this study was to determine the correlation between pncA gene mutations and resistance to four first-line anti-TB drugs as well as treatment history in clinical isolates of Mycobacterium tuberculosis.

Patients and methods

M. tuberculosis clinical isolates were collected from 318 in-patients with smear-positive TB between October 2008 and September 2016 at a major hospital in Zunyi, Guizhou Province of China, and used for drug susceptibility testing against four first-line anti-TB drugs. Genomic DNA extracted from clinical isolates was used for PCR amplification and DNA sequencing of the pncA gene.

Results

Among 318 clinical isolates, 129 (40.6%), 170 (53.5%), 66 (20.8%) and 109 (34.3%) were resistant to rifampicin, isoniazid, ethambutol and streptomycin respectively. In addition, 124 clinical isolates were MDR-TB and 71.8% of them were previously treated cases. Sequencing results showed that 46.8% of MDR-TB and 2.2% of drug susceptible isolates harbored a pncA mutation, and 52 types of pncA mutations were detected from 64 isolates. The prevalence of pncA mutations in isolates resistant to first-line anti-TB drugs and previously treated TB cases was significantly higher than that in drug-susceptible isolates and new cases of TB.

Conclusion

High prevalence of pncA mutations in clinical isolates of M. tuberculosis from Zunyi, Guizhou Province of China, is correlated with resistance to four first-line anti-TB drugs, MDR-TB and previously treated TB cases.

Long-term efficacy of 6-month therapy with isoniazid and rifampin compared with isoniazid, rifampin, and pyrazinamide treatment for pleural tuberculosis

Research into anti-tuberculosis treatment has mainly focused on pulmonary tuberculosis (TB), with few studies on pleural-TB. The aim of the study is to compare the long-term efficacy of a 6-month treatment regimen with isoniazid and rifampicin (6HR) with treatment regimen of isoniazid, rifampicin, and pyrazinamide (6HR2Z) for pleural-TB. A case-control study of 200 HIV-negative patients with pleural-TB prospectively followed in our TB-unit from 1995 to 2018. The primary resistance to isoniazid is < 4% in our geographic area. Pleural-TB diagnosis was based on a positive culture for M. tuberculosis (84 patients), presence of caseating granulomas in pleural biopsy (28), or characteristics of pleural fluid (88). A comparative study of demographic and clinical characteristics between the treatment groups was carried out. Out of the 200 patients followed, (112 males, 88 females; mean age 32.9 ± 18.4 years), 99 patients were treated with 6HR regimen and 101 with 6HR2Z. The groups were comparable, except the 6HR2Z had larger size of pleural effusion. All patients completed the treatment. The group treated with 6HR presented fewer adverse effects (15.3%) than 6HR2Z group (33%), p = 0.005, and lower frequency of severe hepatic toxicity (5% vs 10.9%). Four patients died from causes other than TB during treatment with 6HR2Z, and all other patients were cured during a monitoring period for 8.4 years (IQRs, 3.3-14.3). Six patients in 6HR and 10 in 6HR2Z developed residual pachypleuritis. 6HR is as effective as 6HR2Z treatment for pleural-TB, with fewer adverse effects.

Risk factors for tuberculosis: A case-control study in Addis Ababa, Ethiopia

Background

Tuberculosis remains a major public-health problem in the world, despite several efforts to improve case identification and treatment compliance. It is well known cause of ill-health among millions of people each year and ranks as the second leading cause of death from infectious disease worldwide. Despite implementation of the World health organization recommended strategy, the reductions in the incidence of TB have been minimal in high burden countries.

Objectives and methods

A case control study was carried out to assess the risk factors of TB, where cases were newly registered bacteriologically confirmed pulmonary TB patients with age greater than 15 years who present at twenty health centres in Addis Ababa. Controls were age and sex matched attendees who presented in the same health centers for non-TB health problems.

Results

A total of 260 cases and 260 controls were enrolled in the study and 45.8% of cases and 46.2% of controls were in the 26–45 years age bracket. According to the multivariable logistic regression analysis, seven variables were found to be independent predictors for the occurrence of TB after controlling possible confounders. Patients who live in house with no window or one window were almost two times more likely to develop tuberculosis compared to people whose house has multiple windows (AOR = 1.81; 95% CI:1.06, 3.07). Previous history of hospital admission was found to pose risk almost more than three times (AOR = 3.39; 95% CI: 1.64–7.03). Having a household member who had TB was shown to increase risk of developing TB by three fold (AOR = 3.00; 95% CI: 1.60, 5.62). The study showed that illiterate TB patients were found to be more than twice more likely to develop TB compared to subjects who can atleast read and write (AOR, 95% CI = 2.15, 1.05, 4.40). Patients with household income of less than 1000 birrs per month were more than two times more likely to develop TB compared to those who had higher income (AOR = 2.2; 95% CI: 1.28, 3.78). Smoking has also been identified as important risk factor for developing TB by four times (AOR = 4.43; 95% CI: 2.10, 9.3). BCG was found to be protective against TB reducing the risk by one-third (AOR = 0.34; 95% CI: 0.22, 0.54).

Conclusion

This study showed that TB is more common among the most agile and economically active age group, and number of windows, history of hospital admission, a household member who had TB, illiteracy, low household income and smoking and lack of BCG scar were identified as independent risk factors. Therefore it is imperative that the TB control effort need a strategy to address socio economic issues such as poverty, overcrowding, smoking, and infection control at health care facilities level is an important intervention to prevent transmission of TB within the facilities.

Drug resistance profiles and trends in drug-resistant tuberculosis at a major hospital in Guizhou Province of China

Objectives

Tuberculosis (TB) is the leading cause of death from infectious diseases in the world, with an estimated 1.6 million deaths from TB in 2017. The objectives of this study were to determine drug resistance profiles of Mycobacterium tuberculosis clinical isolates and to analyze the trends in drug-resistant and multidrug-resistant tuberculosis (MDR-TB) from 2008 to 2015 at a major hospital in Guizhou, a high-TB burden and resource-limited province of China.

Patients and methods

A total of 462 clinical isolates were collected from patients with pulmonary TB during the period from January 2013 to December 2015 and used for determining drug resistance profiles against four first-line and six second-line anti-TB drugs, and the results were compared with those of two previous studies.

Results

Exactly 4.4% of new and 44.1% of previously treated TB cases were MDR/rifampicin-resistant TB (RR-TB), which were higher than the 2017 global average numbers of 3.5% and 18%, respectively. There were many drug-resistant patterns among MDR-TB isolates and most of them were resistant to three or four anti-TB drugs. The trends in drug-resistant and MDR-TB declined at the hospital from 2008 to 2015.

Conclusion

Results of this study show that the prevalence of MDR/RR-TB at a major hospital in Guizhou is higher than the global average and confirm the existence of heterogeneity in drug resistance patterns of MDR-TB isolates. Additionally, three practical measures have played an important role in the overall decline of MDR-TB at the hospital from 2008 to 2015.

Improving access to multi-drug resistant tuberculosis diagnostic and health services for refugees and migrants

By the end of 2017, an estimated 68.5 million people were displaced from their homes worldwide, of whom 25.4 million were refugees. The transmission and globalization of multi-drug resistant tuberculosis during refugee migration is a now priority issue in the public health agenda. Political and scientific commitment at the highest national and international levels will be critical to intensifying action in promoting improved health services for migrants and refugees.

Risk factors for multidrug-resistant tuberculosis among tuberculosis patients in Serbia: a case-control study

BACKGROUND

Multidrug resistant (MDR) tuberculosis (TB) represents TB which is simultaneous resistant to at least rifampicin (R) and isoniazid (H). Identifying inadequate therapy as the main cause of this form of the disease and explaining the factors leading to its occurrence, numerous social determinants that affect the risk of developing resistance are highlighted. The objectives of the study was to identify independent factors of MDR-TB among tuberculosis patients.

METHODS

Case-control study was conducted from 1st September 2009 to 1st June 2014 in 31 healthcare institutions in Serbia where MDR-TB and TB patients were treated. TB patients infected with MDR- M. tuberculosis and non MDR- M. tuberculosis strain were considered as cases and controls, respectively. Cases and controls were matched by the date of hospitalization. The data was collected using structured questionnaire with face to face interview. Bivariate and multivariable logistic regression analysis (MLRA) were used to identify determinants associated with MDR-TB.

RESULTS

A total of 124 respondents, 31 cases and 93 controls were participated in the study. MLRA identified six significant independent risk factors for the occurrence of MDR-TB as follows: monthly income of the family (Odds ratio (OR) = 3.71; 95% Confidence Interval (CI) = 1.22-11.28), defaulting from treatment (OR = 3.33; 95% CI = 1.14-9.09), stigma associated with TB (OR = 2.97; 95% CI = 1.18-7.45), subjective feeling of sadness (OR = 4.05; 95% CI = 1.69-9.70), use of sedatives (OR = 2.79; 95% CI = 1.02-7.65) and chronic obstructive pulmonary disease (OR = 4.51; 95% CI = 1.07-18.96).

CONCLUSION

In order to reduce burden of drug resistance, strategies of controlling MDR-TB in Serbia should emphasize multi-sectorial actions, addressing health care and social needs of TB patients.

How Long Does Antimycobacterial Antibiotic-loaded Bone Cement Have In Vitro Activity for Musculoskeletal Tuberculosis?

BACKGROUND

Antibiotic-loaded bone cement is accepted as an effective treatment modality for musculoskeletal tuberculosis. However, comparative information regarding combinations and concentrations of second-line antimycobacterial drugs, such as streptomycin and amoxicillin and clavulanic acid, are lacking.

QUESTIONS/PURPOSES

(1) In antibiotic-loaded cement, is there effective elution of streptomycin and Augmentin^® (amoxicillin and clavulanic acid) individually and in combination? (2) What is the antibacterial activity duration for streptomycin- and amoxicillin and clavulanic acid -loaded cement?

METHODS

Six different types of bone cement discs were created by mixing 40 g bone cement with 1 or 2 g streptomycin only, 0.6 g or 1.2 g Augmentin^® (amoxicillin and clavulanic acid) only, and a combination of 1 g streptomycin plus 0.6 g amoxicillin and clavulanic acid and 2 g streptomycin plus 1.2 g amoxicillin and clavulanic acid. Five bone discs of each type were incubated in phosphate buffered saline for 30 days with renewal of the phosphate buffered saline every day. The quantity of streptomycin and/or amoxicillin and clavulanic acid in eluates were measured by a liquid chromatography-mass spectrometry system, and the antimycobacterial activity of eluates against Mycobacterium tuberculosis H37Rv, were calculated by comparing the minimal inhibitory concentration of each eluate with that of tested drugs using broth dilution assay on microplate.

RESULTS

Streptomycin was detected in eluates for 30 days (in 1 g and 2 g discs), whereas 1.2 g amoxicillin and clavulanate eluted until Day 7 and 0.6 g amoxicillin and clavulanate until Day 3. All eluates in streptomycin-containing discs (streptomycin only, and in combination with amoxicillin and clavulanic acid) had effective antimycobacterial activity for 30 days, while amoxicillin and clavulanate-only preparations were only active until Day 14. The antimycobacterial activity of eluates of 2 g streptomycin plus 1.2 g amoxicillin and clavulanate were higher than those of discs containing 1 g streptomycin plus 0.6 g amoxicillin and clavulanate until Day 3, without differences (Day 3, 1 g streptomycin plus 0.6 g amoxicillin and clavulanate: 17.5 ± 6.85 ug/mL; 2 g streptomycin plus 1.2 g amoxicillin and clavulanate: 32.5 ± 16.77 ug/mL; p = 0.109). After Day 7, however, values of the two combinations remained no different than that of Day 30 (Day 30, 1 g streptomycin plus 0.6 g amoxicillin and clavulanate: 0.88 ± 0.34 ug/mL; 2 g streptomycin plus 1.2 g amoxicillin and clavulanate: 0.59 ± 0.94 ug/mL; p = 0.107).

CONCLUSIONS

Streptomycin, in the form of antibiotic-loaded bone cement, had effective elution characteristics and antimycobacterial effects during a 30-day period, whereas amoxicillin and clavulanate only had effective elution and antimycobacterial characteristics during the early period of this study. The two drugs did not interfere with each other during the elution test.

CLINICAL RELEVANCE

This research revealed that combinations of streptomycin and amoxicillin and clavulanate mixed with bone cement are effective for 30 days. Further trials to determine various different combinations of drugs are necessary to improve the effectiveness of treatments for musculoskeletal tuberculosis.

Distinct Prevalence of Drug-Resistant Tuberculosis in Gansu, China: A Retrospective Study on Drug Susceptibility Profiles Between 2010 and 2014

Limited knowledge is available on regional distribution of antituberculosis (TB) drug resistance and on province-specific time-trends in TB drug susceptibility in China. To obtain the latest information about the dynamics of drug-resistant TB in Gansu province, we conducted a retrospective study and analyzed data on drug resistance among new TB cases diagnosed between June 2010 and May 2014 in Gansu, China. The data were collected from the only TB surveillance and treatment hospital in Gansu and, therefore, represented the epidemiology of TB in the province. The drug resistance was defined based on diagnostic drug susceptibility testing. Overall, 17.3% of TB new cases diagnosed during 2010 to 2014 in Gansu presented resistance to at least one anti-TB drug. And a total of 2.9% of new TB cases have multidrug resistance. The prevalence of multidrug-resistant TB in Gansu was found to resurge after 2013 (2.0%) after a steady decline between 2010 and 2012 (from 7.1% to 1.2%). The drug resistance patterns of TB and their revolution trends in Gansu differed from other regions of China. We report the first epidemiological description of drug-resistant TB in Gansu, which is distinct when compared to other regions. Our data demonstrate that the distribution of drug-resistant TB varies to a great extent among different geographic regions. And the results of our study greatly suggest that the implementation of individualized TB management and regimen policy based on the regional epidemiology of TB drug susceptibility is highly required.

The epidemiology, pathogenesis, transmission, diagnosis, and management of multidrug-resistant, extensively drug-resistant, and incurable tuberculosis

Global tuberculosis incidence has declined marginally over the past decade, and tuberculosis remains out of control in several parts of the world including Africa and Asia. Although tuberculosis control has been effective in some regions of the world, these gains are threatened by the increasing burden of multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis. XDR tuberculosis has evolved in several tuberculosis-endemic countries to drug-incurable or programmatically incurable tuberculosis (totally drug-resistant tuberculosis). This poses several challenges similar to those encountered in the pre-chemotherapy era, including the inability to cure tuberculosis, high mortality, and the need for alternative methods to prevent disease transmission. This phenomenon mirrors the worldwide increase in antimicrobial resistance and the emergence of other MDR pathogens, such as malaria, HIV, and Gram-negative bacteria. MDR and XDR tuberculosis are associated with high morbidity and substantial mortality, are a threat to health-care workers, prohibitively expensive to treat, and are therefore a serious public health problem. In this Commission, we examine several aspects of drug-resistant tuberculosis. The traditional view that acquired resistance to antituberculous drugs is driven by poor compliance and programmatic failure is now being questioned, and several lines of evidence suggest that alternative mechanisms-including pharmacokinetic variability, induction of efflux pumps that transport the drug out of cells, and suboptimal drug penetration into tuberculosis lesions-are likely crucial to the pathogenesis of drug-resistant tuberculosis. These factors have implications for the design of new interventions, drug delivery and dosing mechanisms, and public health policy. We discuss epidemiology and transmission dynamics, including new insights into the fundamental biology of transmission, and we review the utility of newer diagnostic tools, including molecular tests and next-generation whole-genome sequencing, and their potential for clinical effectiveness. Relevant research priorities are highlighted, including optimal medical and surgical management, the role of newer and repurposed drugs (including bedaquiline, delamanid, and linezolid), pharmacokinetic and pharmacodynamic considerations, preventive strategies (such as prophylaxis in MDR and XDR contacts), palliative and patient-orientated care aspects, and medicolegal and ethical issues.

Learning from the past for TB drug discovery in the future

Tuberculosis drug discovery has shifted in recent years from a primarily target-based approach to one that uses phenotypic high-throughput screens. As examples of this, through our EU-funded FP7 collaborations, New Medicines for Tuberculosis was target-based and our more-recent More Medicines for Tuberculosis project predominantly used phenotypic screening. From these projects we have examples of success (DprE1) and failure (PimA) going from drug to target and from target to drug, respectively. It is clear that we still have much to learn about the drug targets and the complex effects of the drugs on Mycobacterium tuberculosis. We propose a more integrated approach that learns from earlier drug discovery efforts that could help to move drug discovery forward.

Multidrug-resistant tuberculosis and migration to Europe

Multidrug-resistant tuberculosis (MDR-TB) in low-incidence countries in Europe is more prevalent among migrants than the native population. The impact of the recent increase in migration to EU and EEA countries with a low incidence of TB (<20 cases per 100 000) on MDR-TB epidemiology is unclear. This narrative review synthesizes evidence on MDR-TB and migration identified through an expert panel and database search. A significant proportion of MDR-TB cases in migrants result from reactivation of latent infection. Refugees and asylum seekers may have a heightened risk of MDR-TB infection and worse outcomes. Although concerns have been raised around 'health tourists' migrating for MDR-TB treatment, numbers are probably small and data are lacking. Migrants experience significant barriers to testing and treatment for MDR-TB, exacerbated by increasingly restrictive health systems. Screening for latent MDR-TB is highly problematic because current tests cannot distinguish drug-resistant latent infection, and evidence-based guidance for treatment of latent infection in contacts of MDR patients is lacking. Although there is evidence that transmission of TB from migrants to the general population is low-it predominantly occurs within migrant communities-there is a human rights obligation to improve the diagnosis, treatment and prevention of MDR-TB in migrants. Further research is needed into MDR-TB and migration, the impact of screening on detection or prevention, and the potential consequences of failing to treat and prevent MDR-TB among migrants in Europe. An evidence-base is urgently needed to inform guidelines for effective approaches for MDR-TB management in migrant populations in Europe.

Raising awareness of the importance of funding for tuberculosis small-molecule research

Tuberculosis (TB) drug discovery research is hampered by several factors, but as in many research areas, the available funding is insufficient to support the needs of research and development. Recent years have seen various large collaborative efforts involving public-private partnerships, mimicking the situation during the golden age of antibiotic drug discovery during the 1950s and 1960s. The large-scale collaborative efforts funded by the European Union (EU) are now subject to diminishing financial support. As a result, TB researchers are increasingly looking for novel forms of funding, such as crowdfunding, to fill this gap. Any potential solution will require a careful reassessment of the incentives to encourage additional organizations to provide funding.

Mycobacterium tuberculosis lipoproteins in virulence and immunity - fighting with a double-edged sword

Bacterial lipoproteins are secreted membrane-anchored proteins characterized by a lipobox motif. This lipobox motif directs post-translational modifications at the conserved cysteine through the consecutive action of three enzymes: Lgt, LspA and Lnt, which results in di- or triacylated forms. Lipoproteins are abundant in all bacteria including Mycobacterium tuberculosis and often involved in virulence and immunoregulatory processes. On the one hand, disruption of the biosynthesis pathway of lipoproteins leads to attenuation of M. tuberculosis in vivo, and mycobacteria deficient for certain lipoproteins have been assessed as attenuated live vaccine candidates. On the other hand, several mycobacterial lipoproteins form immunodominant antigens which promote an immune response. Some of these have been explored in DNA or subunit vaccination approaches against tuberculosis. The immune recognition of specific lipoproteins, however, might also benefit long-term survival of M. tuberculosis through immune modulation, while others induce protective responses. Exploiting lipoproteins as vaccines is thus a complex matter which requires deliberative investigation. The dual role of lipoproteins in the immunity to and pathogenicity of mycobacteria is discussed here.

Discordance across Phenotypic and Molecular Methods for Drug Susceptibility Testing of Drug-Resistant Mycobacterium tuberculosis Isolates in a Low TB Incidence Country

With increasing incidence of multidrug-resistant tuberculosis (MDR-TB), accurate drug susceptibility testing (DST) of Mycobacterium tuberculosis to first-line drugs has become crucial for proper patient management. We evaluated concordance of DST results for 70 M. tuberculosis isolates across two phenotypic and two molecular methods: BACTEC 460TB, MGIT 960 system, GenoType MTBDRplus and DNA sequencing of gene segments most commonly implicated in conferring resistance to anti-TB drugs. Most (84%) M. tuberculosis isolates were multidrug-resistant. Twenty-four isolates yielded discrepant DST results. For rifampicin, isoniazid and streptomycin, 96%, 97% and 93% of isolates, respectively, were susceptible or resistant by all four methods, whereas for ethambutol, this agreement was observed for only 76% of isolates (P<0.05 for rifampicin or isoniazid or streptomycin versus ethambutol). Occurrence of rare mutations in three isolates that confer low-level resistance caused lower agreement for rifampicin among the four methods (kappa coefficient (κ) range, 0.84 to 0.95). For isoniazid, there was perfect agreement among phenotypic methods and molecular methods (κ, 1.00) but lower agreement between phenotypic and molecular methods. Three isolates were detected as polydrug-resistant by MGIT 960 system but as multidrug-resistant by DNA sequence-based method. The agreement was higher for streptomycin among the two phenotypic methods (κ, 0.97) while targeted sequencing yielded lower agreement (κ range, 0.86 to 0.89). The discrepancy for ethambutol resulted largely due to lower concordance of MGIT 960 results (κ range, 0.53 to 0.64). The MGIT 960 system is an accurate method for DST of M. tuberculosis against isoniazid and streptomycin while the results of rifampicin susceptibility should be complemented with DNA sequencing-based method when the suspicion for resistance is high. The possibility of false susceptibility to ethambutol with MGIT 960 system suggests that molecular or other phenotypic methods may be more useful when accurate ethambutol susceptibility results are warranted.

Survival of patients with multidrug-resistant TB in Eastern Europe: what makes a difference?

BACKGROUND

The quality of care for patients with TB in Eastern Europe has improved significantly; nevertheless drug resistance rates remain high. We analysed survival in a cohort of patients with multidrug-resistant and extensively drug-resistant (MDR-/XDR-) TB from Latvia, Lithuania, Estonia and Bucharest city.

METHODS

Consecutive adult new and retreatment patients with culture-confirmed pulmonary MDR-TB registered for treatment in 2009 (and in 2007 in Latvia) were enrolled; prospective survival information was collected.

RESULTS

A total of 737 patients were included into the cohort. Of all MDR-TB cases, 46% were newly diagnosed; 56% of all MDR-TB cases had no additional resistance to fluoroquinolones or injectable agents, 33% had pre-XDR-TB and 11% XDR-TB. Median survival was 5.9 years in patients with MDR-TB and XDR-TB; 1.9 years in patients coinfected with HIV. Older age, male gender, alcohol abuse, retirement, co-morbidities, extrapulmonary involvement and HIV coinfection independently worsened survival. Inclusion of fluoroquinolones and injectable agents improves survival in patients with MDR-TB. Pre-XDR and XDR status did not significantly shorten survival as long as fluoroquinolones and injectable agents were part of the regimen. Moxifloxacin seems to improve survival in ofloxacin-susceptible patients when compared with older generation fluoroquinolones.

CONCLUSIONS

The burden of additional resistances in patients with MDR-TB is high likely due to primary transmission of resistant strains. Social and programmatic factors including management of alcohol dependency, expansion of HIV testing and antiretroviral treatment need to be addressed in order to achieve cure and to interrupt transmission. The role of last generation fluoroquinolones and injectable agents in treatment of patients with pre-XDR and XDR-TB needs to be further investigated.

Multidrug-resistant tuberculosis in Lithuania - Still a long way ahead

Despite the recent advances in the diagnosis of tuberculosis, treatment of the disease, for the most part, remains the same as it was half a century ago. In recent years only two new anti-tuberculosis drugs have been approved by the European Medicines Agency and Food and Drug Administration. Though the prevalence of this disease is slowly decreasing all over Europe, new challenges appear. One of them is multidrug-resistant tuberculosis (MDR-TB). This problem is especially prominent in Lithuania, which is one of the 27 high MDR-TB burden countries in the world and falls behind neighboring countries in terms of the prevalence of the disease. The objective of this paper was to review the situation of tuberculosis and MDR-TB in Lithuania, and current available methods of treatment, control and diagnosis of this disease.

Risk factors for acquisition of drug resistance during multidrug-resistant tuberculosis treatment, Arkhangelsk Oblast, Russia, 2005-2010

Resistance should be determined quickly, and treatment should contain at least 3 effective drugs.

Acquired resistance to antituberculosis drugs decreases effective treatment options and the likelihood of treatment success. We identified risk factors for acquisition of drug resistance during treatment for multidrug-resistant tuberculosis (MDR TB) and evaluated the effect on treatment outcomes. Data were collected prospectively from adults from Arkhangelsk Oblast, Russia, who had pulmonary MDR TB during 2005–2008. Acquisition of resistance to capreomycin and of extensively drug-resistant TB were more likely among patients who received <3 effective drugs than among patients who received >3 effective drugs (9.4% vs. 0% and 8.6% vs. 0.8%, respectively). Poor outcomes were more likely among patients with acquired capreomycin resistance (100% vs. 25.9%), acquired ofloxacin resistance (83.6% vs. 22.7%), or acquired extensive drug resistance (100% vs. 24.4%). To prevent acquired drug resistance and poor outcomes, baseline susceptibility to first- and second-line drugs should be determined quickly, and treatment should be adjusted to contain >3 effective drugs.

Drug Susceptibility Patterns in MDR-TB Patients: Challenges for Future Regimen Design. A Cross-Sectional Study

Globally, there is substantial concern regarding the challenges of treating complex drug resistance patterns in multidrug resistant tuberculosis cases. Utilising data from three different settings (Estonia, Latvia, Romania) we sought to contrast drug susceptibility profiles for multidrug resistant tuberculosis cases, highlight the difficulties in designing universal regimen, and inform future regimen selection. Demographic and microbiological surveillance data for multidrug resistant tuberculosis cases from 2004-13 were analysed. High levels of additional resistance to currently recommended second line drugs were seen in all settings, with extensive variability between countries. Accurate drug susceptibility testing and drug susceptibility testing data are vital to inform the development of comprehensive, flexible, multidrug resistant tuberculosis guidance.

High time to use rapid tests to detect multidrug resistance in sputum smear-negative tuberculosis in Belarus

SETTING

Belarus (Eastern Europe) is facing an epidemic of multidrug-resistant tuberculosis (MDR-TB). In 2012, rapid molecular diagnostics were prioritised for sputum smear-positive pulmonary tuberculosis (PTB) patients to diagnose MDR-TB, while pulmonary sputum smear-negative pulmonary TB (SN-PTB) patients were investigated using conventional methods, often delaying the diagnosis of MDR-TB by 2-4 months.

OBJECTIVE

To determine the proportion of MDR-TB among SN-PTB patients registered in 2012 and associated clinical and demographic factors.

DESIGN

Retrospective cohort study using countrywide data from the national electronic TB register.

RESULTS

Of the 5377 TB cases registered, 2960 (55%) were SN-PTB. Of the latter, 1639 (55%) were culture-positive, of whom 768 (47%) had MDR-TB: 33% (363/1084) were new and 73% (405/555) previously treated patients. Previous history of treatment, age, region, urban residence, human immunodeficiency virus (HIV) status and being a pensioner were independently associated with MDR-TB.

CONCLUSION

About half of culture-positive SN-PTB patients have MDR-TB and this rises to over 7/10 for retreatment cases. A national policy decision to extend rapid molecular diagnostics universally to all PTB patients, including SN-PTB, seems justified. Steps need to be taken to ensure implementation of this urgent priority, given the patient and public health implications of delayed diagnosis.

First national survey of anti-tuberculosis drug resistance in Azerbaijan and risk factors analysis

SETTING

Civilian population of the Republic of Azerbaijan.

OBJECTIVES

To determine patterns of anti-tuberculosis drug resistance among new and previously treated pulmonary tuberculosis (TB) cases, and explore their association with socio-demographic and clinical characteristics.

DESIGN

National cross-sectional survey conducted in 2012-2013.

RESULTS

Of 789 patients (549 new and 240 previously treated) who met the enrolment criteria, 231 (42%) new and 146 (61%) previously treated patients were resistant to any anti-tuberculosis drug; 72 (13%) new and 66 (28%) previously treated patients had multidrug-resistant TB (MDR-TB). Among MDR-TB cases, 38% of new and 46% of previously treated cases had pre-extensively drug-resistant TB (pre-XDR-TB) or XDR-TB. In previously treated cases, 51% of those who had failed treatment had MDR-TB, which was 15 times higher than in relapse cases (OR 15.2, 95%CI 6-39). The only characteristic significantly associated with MDR-TB was a history of previous treatment (OR 3.1, 95%CI 2.1-4.7); for this group, history of incarceration was an additional risk factor for MDR-TB (OR 2.8, 95%CI 1.1-7.4).

CONCLUSION

Azerbaijan remains a high MDR-TB burden country. There is a need to implement countrywide control and innovative measures to accelerate early diagnosis of drug resistance in individual patients, improve treatment adherence and strengthen routine surveillance of drug resistance.

Drug-resistant tuberculosis in Eastern Europe: challenges and ways forward

Encouragingly, global rates of new tuberculosis (TB) cases have been falling since 2005, in line with the Millennium Development Goal targets; however, cases of multidrug-resistant (MDR-) and extensively drug-resistant TB (XDR-TB) have been increasing. Fifteen of the world's 27 high MDR- and XDR-TB burden countries are in the World Health Organization (WHO) European Region, of which 10 are in Eastern Europe (including Baltic and Caucasus countries). To address the MDR- and XDR-TB situation in the WHO European Region, a Consolidated Action Plan to Prevent and Combat M/XDR-TB (2011-2015) was developed for all 53 Member States and implemented in 2011. Since the implementation of the Action Plan, the proportion of MDR-TB appears largely to have levelled off among bacteriologically confirmed TB cases in high-burden countries with universal or near universal (>95%) first-line drug susceptibility testing (DST). The treatment success rate, however, continues to decrease. A contributing factor is the substantial proportion of MDR-TB cases that are additionally resistant to either a fluoroquinolone, a second-line injectable agent or both (XDR-TB); high-burden country proportions range from 12.6% to 80.4%. Proportions of XDR-TB range from 5% to 24.8%. Despite much progress in Eastern Europe, critical challenges remain as regards access to appropriate treatment regimens; patient hospitalisation; scale-up of laboratory capacity, including the use of rapid diagnostics and second-line DST; vulnerable populations; human resources; and financing. Solutions to these challenges are aligned with the Post-2015 Global TB strategy. As a first step, the global strategy should be adapted at regional and country levels to serve as a framework for immediate actions as well as longer-term ways forward.

Design and structure of the Estonian HIV Cohort Study (E-HIV)

BACKGROUND

Estonia is experiencing the new Eastern Europe human immunodeficiency virus (HIV) epidemic, with the highest incidence of new infections in the EU. We describe demographic changes, HIV-related laboratory parameters and co-infections during the concentrated HIV epidemic using the Estonian HIV Cohort Study (E-HIV) database, founded in 2009.

METHODS

All 3750 subjects in the E-HIV database on December 31, 2013 were included. Subjects were divided into risk groups: people who inject drugs (PWIDs), sexual transmission (heterosexual/homosexual), and other (perinatal) or unknown risk group. Subjects diagnosed before 2009 (first period) and after (second period) were analyzed separately.

RESULTS

The mean age at diagnosis has increased from 22.8 years (interquartile range (IQR) = 19.5-27.2) to 29.7 years (IQR = 25.3-36.2) (p < 0.001) between the first and second periods. PWIDs were younger than other transmission groups (23.2 vs 27.1; p < 0.001). There is a statistical difference in the route of transmission among genders, with overall increasing sexual transmission. The most common AIDS-defining illness was tuberculosis (0.5%). HIV/hepatitis C (HCV) co-infection was diagnosed in 42% of cases. The population median CD4 + cell count at diagnosis has declined over the years; in total 53% have been late presenters. Half of the patients are receiving antiretroviral treatment (cART). The most common combinations are nucleoside reverse transcriptase inhibitor (NRTI) backbone plus protease inhibitors (PIs) (57%) or NRTI backbone + non-NRTIs (42%).

CONCLUSION

The E-HIV enables us to fill the gap in the lack of data on the course of the new Eastern European HIV epidemic. These data demonstrate that the HIV epidemic in Estonia is moving from PWIDs to the general population, suggesting that prevention measures and testing guidelines should be revised.

New anti-tuberculosis drugs and regimens: 2015 update

Over 480 000 cases of multidrug-resistant (MDR) tuberculosis (TB) occur every year globally, 9% of them being affected by extensively drug-resistant (XDR) strains of Mycobacterium tuberculosis. The treatment of MDR/XDR-TB is unfortunately long, toxic and expensive, and the success rate largely unsatisfactory (<20% among cases with resistance patterns beyond XDR).

The aim of this review is to summarise the available evidence-based updated international recommendations to manage MDR/XDR-TB, and to update the reader on the role of newly developed drugs (delamanid, bedaquiline and pretomanid) as well as repurposed drugs (linezolid and meropenem clavulanate, among others) used to treat these conditions within new regimens.

A nonsystematic review based on historical trials results as well as on recent literature and World Health Organization (WHO) guidelines has been performed, with special focus on the approach to managing MDR/XDR-TB.

The new, innovative global public health interventions, recently approved by WHO and known as the “End TB Strategy”, support the vision of a TB-free world with zero death, disease and suffering due to TB. Adequate, universally accessed treatment is a pre-requisite to reach TB elimination. New shorter, cheap, safe and effective anti-TB regimens are necessary to boost TB elimination.

The new WHO post-2015 End TB Strategy will support the efforts that research on new drugs and regimens requireshttp://ow.ly/LnJER

Variation and risk factors of drug resistant tuberculosis in sub-Saharan Africa: a systematic review and meta-analysis

Background

Prevalence of multidrug resistant tuberculosis (MDR-TB), defined as in vitro resistance to both rifampicin and isoniazid with or without resistance to other TB drugs, in sub-Saharan Africa (SSA) is reportedly low compared to other regions. These estimates are based on data reported to the World Health Organization (WHO) on drug resistance surveys, which may suffer from a reporting bias. We set out to evaluate the variation in prevalence of drug resistant tuberculosis (DR-TB) and its determinants across SSA countries among new and previously treated TB patients.

Methods

The aim was to perform a systematic review and meta-analysis of DR-TB prevalence and associated risk factors in SSA. PubMed, EMBASE, Cochrane and bibliographies of DR-TB studies were searched. Surveys at national or sub-national level, with reported DR-TB prevalence (or sufficient data to calculate a prevalence) to isoniazid (INH), rifampicin (RMP), ethambutol (EMB), and streptomycin (SM) conducted in SSA excluding the Republic of South Africa, published between 2003 and 2013 with no language restriction were considered. Two authors searched and reviewed the studies for eligibility and extracted the data in pre-defined forms. Forest plots of all prevalence estimates by resistance outcome were performed. Summary estimates were calculated using random effects models, when appropriate. Associations between any DR-TB and MDR-TB with potential risk factors were examined through subgroup analyses stratified by new and previously treated patients.

Results

A total of 726 studies were identified, of which 27 articles fulfilled the inclusion criteria. Studies reported drug susceptibility testing (DST) results for a total of 13,465 new and 1,776 previously treated TB patients. Pooled estimate of any DR-TB prevalence among the new cases was 12.6% (95% CI 10.6-15.0) while for MDR-TB this was 1.5% (95% CI 1.0-2.3). Among previously treated patients, these were 27.2% (95% CI 21.4-33.8) and 10.3% (95% CI 5.8-17.4%), respectively. DR-TB (any and MDR-TB) did not vary significantly with respect to study characteristics.

Conclusions

The reported prevalence of DR-TB in SSA is low compared to WHO estimates. MDR-TB in this region does not seem to be driven by the high HIV prevalence rates.

Regulatory T-cell subsets in response to specific Mycobacterium tuberculosis antigens in vitro distinguish among individuals with different QTF and TST reactivity

Regulatory T cells (Tregs), a subset of CD4+ T cells related with immune regulation, have been associated with active and latent tuberculosis infection (LTBI). Treg frequencies were evaluated by multicolor flow cytometry (FC) in peripheral blood mononuclear cells (PBMCs) stimulated with mycobacterial antigens ESAT-6, CFP-10, and TB7.7 to assess their capacity to distinguish subjects with different reactivity to the QuantiFERON-TB® Gold In-Tube (QFT-IT) test and the tuberculin skin test (TST). Increased frequencies of CD4+CD25highCD39+ cells were found for the [TST+, QTF+] compared with the [TST+, QTF-] group. Also, higher frequencies were observed for the [TST+, QTF+] compared with the [TST+, QTF-] and [TST-, QTF-] groups in CD4+CD25highFoxp3+ and CD4+CD25highCD39+Foxp3+ populations. Receiver operating characteristics (ROC curve) analysis confirmed these discriminating results. QFT-IT and TST quantitative values correlated with several Treg population frequencies.

Cutaneous tuberculosis overview and current treatment regimens

Tuberculosis is one of the oldest diseases known to humankind and it is currently a worldwide threat with 8-9 million new active disease being reported every year. Among patients with co-infection of the human immunodeficiency virus (HIV), tuberculosis is ultimately responsible for the most deaths. Cutaneous tuberculosis (CTB) is uncommon, comprising 1-1.5% of all extra-pulmonary tuberculosis manifestations, which manifests only in 8.4-13.7% of all tuberculosis cases. A more accurate classification of CTB includes inoculation tuberculosis, tuberculosis from an endogenous source and haematogenous tuberculosis. There is furthermore a definite distinction between true CTB caused by Mycobacterium tuberculosis and CTB caused by atypical mycobacterium species. The lesions caused by mycobacterium species vary from small papules (e.g. primary inoculation tuberculosis) and warty lesions (e.g. tuberculosis verrucosa cutis) to massive ulcers (e.g. Buruli ulcer) and plaques (e.g. lupus vulgaris) that can be highly deformative. Treatment options for CTB are currently limited to conventional oral therapy and occasional surgical intervention in cases that require it. True CTB is treated with a combination of rifampicin, ethambutol, pyrazinamide, isoniazid and streptomycin that is tailored to individual needs. Atypical mycobacterium infections are mostly resistant to anti-tuberculous drugs and only respond to certain antibiotics. As in the case of pulmonary TB, various and relatively wide-ranging treatment regimens are available, although patient compliance is poor. The development of multi-drug and extremely drug-resistant strains has also threatened treatment outcomes. To date, no topical therapy for CTB has been identified and although conventional therapy has mostly shown positive results, there is a lack of other treatment regimens.

Intra- and extracellular activities of trimethoprim-sulfamethoxazole against susceptible and multidrug-resistant Mycobacterium tuberculosis

We investigated the activity of trimethoprim-sulfamethoxazole (SXT) against Mycobacterium tuberculosis, the pathogen that causes tuberculosis (TB). The MIC distribution of SXT was 0.125/2.4 to 2/38 mg/liter for the 100 isolates tested, including multi- and extensively drug-resistant isolates (MDR/XDR-TB), whereas the intracellular MIC90 of sulfamethoxazole (SMX) for the pansusceptible strain H37Rv was 76 mg/liter. In an exploratory analysis using a ratio of the unbound area under the concentration-time curve from 0 to 24 h over MIC (fAUC0-24/MIC) using ≥ 25 as a potential target, the cumulative fraction response was ≥ 90% at doses of ≥ 2,400 mg of SMX. SXT is a potential treatment option for MDR/XDR-TB.