Acquired and Transmitted Multidrug Resistant Tuberculosis: The Role of Social Determinants

Drug-resistant tuberculosis: a persistent global health concern

Drug-resistant tuberculosis (TB) is estimated to cause 13% of all antimicrobial resistance-attributable deaths worldwide and is driven by both ongoing resistance acquisition and person-to-person transmission. Poor outcomes are exacerbated by late diagnosis and inadequate access to effective treatment. Advances in rapid molecular testing have recently improved the diagnosis of TB and drug resistance. Next-generation sequencing of Mycobacterium tuberculosis has increased our understanding of genetic resistance mechanisms and can now detect mutations associated with resistance phenotypes. All-oral, shorter drug regimens that can achieve high cure rates of drug-resistant TB within 6-9 months are now available and recommended but have yet to be scaled to global clinical use. Promising regimens for the prevention of drug-resistant TB among high-risk contacts are supported by early clinical trial data but final results are pending. A person-centred approach is crucial in managing drug-resistant TB to reduce the risk of poor treatment outcomes, side effects, stigma and mental health burden associated with the diagnosis. In this Review, we describe current surveillance of drug-resistant TB and the causes, risk factors and determinants of drug resistance as well as the stigma and mental health considerations associated with it. We discuss recent advances in diagnostics and drug-susceptibility testing and outline the progress in developing better treatment and preventive therapies.

Who Transmits Tuberculosis to Whom: A Cross-Sectional Analysis of a Cohort Study in Lima, Peru

Rationale: The persistent burden of tuberculosis (TB) disease emphasizes the need to identify individuals with TB for treatment and those at a high risk of incident TB for prevention. Targeting interventions toward those at high risk of developing and transmitting TB is a public health priority. Objectives: We aimed to identify characteristics of individuals involved in TB transmission in a community setting, which may guide the prioritization of targeted interventions. Methods: We collected clinical and sociodemographic data from a cohort of patients with TB in Lima, Peru. We used whole-genome sequencing data to assess the genetic distance between all possible pairs of patients; we considered pairs to be the result of a direct transmission event if they differed by three or fewer SNPs, and we assumed that the first diagnosed patient in a pair was the transmitter and the second was the recipient. We used logistic regression to examine the association between host factors and the likelihood of direct TB transmission. Measurements and Main Results: Analyzing data from 2,518 index patients with TB, we identified 1,447 direct transmission pairs. Regardless of recipient attributes, individuals less than 34 years old, males, and those with a history of incarceration had a higher likelihood of being transmitters in direct transmission pairs. Direct transmission was more likely when both patients were drinkers or smokers. Conclusions: This study identifies men, young adults, former prisoners, alcohol consumers, and smokers as priority groups for targeted interventions. Innovative strategies are needed to extend TB screening to social groups such as young adults and prisoners with limited access to routine preventive care.

Association between HIV and acquisition of rifamycin resistance with first-line TB treatment: a systematic review and meta-analysis

BACKGROUND

Multi-drug or rifamycin-resistant tuberculosis (MDR/RR-TB) is an important public health concern, including in settings with high HIV prevalence. TB drug resistance can be directly transmitted or arise through resistance acquisition during first-line TB treatment. Limited evidence suggests that people living with HIV (PLHIV) might have an increased risk of acquired rifamycin-resistance (ARR).

METHODS

To assess HIV as a risk factor for ARR during first-line TB treatment, a systematic review and meta-analysis was conducted. ARR was defined as rifamycin-susceptibility at treatment start with rifamycin-resistance diagnosed during or at the end of treatment, or at recurrence. PubMed/MEDLINE, CINAHL, Cochrane Library, and Google Scholar databases were searched from inception to 23 May 2024 for articles in English; conference abstracts were also searched from 2004 to 2021. The Mantel-Haenszel random-effects model was used to estimate the pooled odds ratio of any association between HIV and ARR among individuals receiving first-line TB treatment.

RESULTS

Ten studies that included data collected between 1990 and 2014 were identified: five from the United States, two from South Africa and one each from Uganda, India and Moldova. A total of 97,564 individuals were included across all studies, with 13,359 (13.7%) PLHIV. Overall, 312 (0.32%) acquired rifamycin-resistance, among whom 115 (36.9%) were PLHIV. The weighted odds of ARR were 4.57 (95% CI, 2.01-10.42) times higher among PLHIV compared to HIV-negative individuals receiving first-line TB treatment.

CONCLUSION

The available data, suggest that PLHIV have an increased ARR risk during first-line TB treatment. Further research is needed to clarify specific risk factors, including advanced HIV disease and TB disease severity. Given the introduction of shorter, 4-month rifamycin-based regimens, there is an urgent need for additional data on ARR, particularly for PLHIV.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42022327337.

Latent TB and depressive symptoms in household contacts of persons with active TB

BACKGROUND: Depression is common among persons with TB and is associated with poor clinical outcomes. However, little is known about the relationship between latent TB infection (LTBI) and depression. We assessed the association between LTBI and depressive symptoms among household contacts (HHCs) of patients receiving TB treatment.METHODS: We enrolled 1,009 HHCs of 307 patients receiving TB treatment in Lima, Peru, during 2016-2018. At enrollment, HHC LTBI status was assessed using the interferon-gamma release assay (IGRA). Depressive symptoms were assessed at baseline and 12 months later using the Patient Health Questionnaire-9 (PHQ-9) with a cut-off of ≥5. We used logistic regression to estimate the odds ratio (OR) for PHQ-9 ≥5, comparing HHCs with and without baseline LTBI.RESULTS: Among 921 HHCs, 374 (41.0%) had LTBI at baseline, and 69 (12.4%) of 567 HHCs had PHQ-9 ≥5. Compared to HHCs without LTBI at enrollment, those with LTBI had almost two times the odds of PHQ-9 ≥5 at follow-up after controlling for potential confounders (adjusted OR 1.93, 95% CI 1.09-3.39); this association was driven by greater severities of depressive symptoms.CONCLUSION: HHCs with LTBI had increased odds of depressive symptoms 1 year later. This population may benefit from mental health screening and interventions integrated into TB programs.

Association between overweight/obesity and multidrug-resistant tuberculosis

OBJECTIVE.

To evaluate the association between overweight/obesity and multidrug resistance in patients with and without a history of tuberculosis treatment.

MATERIALS AND METHODS.

Cross-sectional study of secondary data from a tuberculosis cohort, which included anthropometric and drug-sensitivity testing data at the baseline visit of patients with and without previous tuberculosis treatment.

RESULTS.

We evaluated 3,734 new cases and 766 with a history of having received treatment for tuberculosis. Overweight/obesity was not associated with multidrug resistance in patients with a history of tuberculosis treatment, with a prevalence ratio of 0.97 and a 95% confidence interval of 0.68-1.38.

CONCLUSIONS.

Overweight/obesity is not associated with multidrug resistance in tuberculosis. Overweight/obesity is a dynamic process that may influence the relationship between the immune system and the metabolic system.

Higher native Peruvian genetic ancestry proportion is associated with tuberculosis progression risk

We investigated whether ancestry-specific genetic factors affect tuberculosis (TB) progression risk in a cohort of admixed Peruvians. We genotyped 2,105 patients with TB and 1,320 household contacts (HHCs) who were infected with Mycobacterium tuberculosis (M. tb) but did not develop TB and inferred each individual’s proportion of native Peruvian genetic ancestry. Our HHC study design and our data on potential confounders allowed us to demonstrate increased risk independent of socioeconomic factors. A 10% increase in individual-level native Peruvian genetic ancestry proportion corresponded to a 25% increased TB progression risk. This corresponds to a 3-fold increased risk for individuals in the highest decile of native Peruvian genetic ancestry versus the lowest decile, making native Peruvian genetic ancestry comparable in effect to clinical factors such as diabetes. Our results suggest that genetic ancestry is a major contributor to TB progression risk and highlight the value of including diverse populations in host genetic studies.

Our understanding of how genetic differences among human populations may affect susceptibility to infectious diseases is very limited. Asgari et al. show that the proportion of native genetic ancestry in contemporary Peruvians affects the risk of progression from latent to active tuberculosis even after accounting for differences in socio-demographic factors.

Epidemiological and laboratory characteristics of multidrug-resistant tuberculosis patients in Bhutan, 2015-2019

•

Multidrug-resistant tuberculosis (MDR-TB) reported in high numbers of new TB cases

•

Majority of MDR-TB patients in the economically productive age group

•

No major variations in mutation pattern for Line Probe Assay results across 5 years

Background

Bhutan is no exception to the rising global threat of drug resistance tuberculosis (TB), particularly multidrug-resistant (MDR) TB. Although drug resistance surveillance has been carried out in Bhutan since 2010, limited analysis reports are available. Therefore, we looked at data from 2015−2019 to understand patient characteristics.

Method

To obtain data for MDR-TB from the past 5 years, we looked at manual registers and laboratory worksheets for all samples received at National TB Reference Laboratory. Epidemiological factors and laboratory variables were analyzed using descriptive statistics.

Result

Among 304 patients with MDR-TB, 85.20% (n=259) are new cases with no previous history of treatment. Those aged 16−25 years from both genders are affected more (46.05%, n=140) than other age groups. The majority (94.62%, n=264) of rifampicin resistance was found in the MUT 3 rpoB gene. For Isoniazid, 97.13% (n=271) resistance was seen in the MUT1 band of the katG gene.

Conclusion

A high number of MDR-TB cases among new patients and little variation in the resistance band pattern over 5 years could indicate uncontrolled ongoing transmission. Whole-genome sequencing for the samples is required to further understand the epidemiology of the resistance pattern.

Repurposing Based Identification of Novel Inhibitors against MmpS5-MmpL5 Efflux Pump of Mycobacterium smegmatis: A Combined In Silico and In Vitro Study

In the current era of a pandemic, infections of COVID-19 and Tuberculosis (TB) enhance the detrimental effects of both diseases in suffering individuals. The resistance mechanisms evolving in Mycobacterium tuberculosis are limiting the efficiency of current therapeutic measures and pressurizing the stressed medical infrastructures. The bacterial efflux pumps enable the development of resistance against recently approved drugs such as bedaquiline and clofazimine. Consequently, the MmpS5-MmpL5 protein system was selected because of its role in efflux pumping of anti-TB drugs. The MmpS5-MmpL5 systems of Mycobacterium smegmatis were modelled and the virtual screening was performed using an ASINEX library of 5968 anti-bacterial compounds. The inhibitors with the highest binding affinities and QSAR based highest predicted inhibitory concentration were selected. The MmpS5-MmpL5 associated systems with BDE_26593610 and BDD_27860195 showed highest inhibitory parameters. These were subjected to 100 ns Molecular Dynamics simulations and provided the validation regarding the interaction studies. The in vitro studies demonstrated that the BDE_26593610 and BDD_27860195 can be considered as active inhibitors for M. smegmatis MmpS5-MmpL5. The outcomes of this study can be utilized in other experimentation aimed at drug design and discovery against the drug resistance strains of M. tuberculosis.

Primary and acquired multidrug-resistant tuberculosis: Predictive factors for unfavorable treatment outcomes in Rio de Janeiro, 2000-2016

Objective

To identify clinical and demographic factors associated with unfavorable treatment outcomes in patients with primary and acquired multidrug-resistant tuberculosis (MDR-TB) in Rio de Janeiro State.

Methods

Retrospective cohort study using data on 2 269 MDR-TB cases in 2000–2016. Factors associated with unsuccessful, loss to follow-up, and death outcomes in patients with primary and acquired resistance were investigated with bivariate and multivariate regression.

Results

Primary resistance was 14.7% among MDR-TB cases. The unfavorable outcomes proportion was 30.3% in the primary resistance group and 46.7% in the acquired resistance group. There were significant differences in demographic and clinical characteristics between the two groups. Proportionally, the group with primary resistance had more cases among women (46.4% vs. 33.5% in the acquired resistance group), Caucasians (47.3% and 34%), and those with ≥8 years of schooling (37.7% and 27.4%). Extensively drug-resistant TB patients had 12.2-fold higher odds of unsuccessful outcome than MDR-TB patients, and comorbidities had 2-fold higher odds in the primary resistance group. Extensively drug-resistant TB had 5.43-fold higher odds in the acquired MDR-TB group. Bilateral disease and <8 years of schooling were associated with unsuccessful outcome in both groups. Being an inmate had 8-fold higher odds of loss to follow-up in the primary resistance group. Culture conversion by the sixth month was a protective factor for all outcomes.

Conclusions

Primary resistance cases of MDR-TB constitute a different transmission reservoir, which is related to other chronic diseases associated with higher acquisition of TB. The poor results observed in Rio de Janeiro State can contribute to increasing the transmission of primary MDR-TB, thus favoring drug resistance.

Rifampicin-Resistant Mycobacterium tuberculosis Among Patients with Presumptive Tuberculosis in Addis Ababa, Ethiopia

Background

Drug-resistant tuberculosis remains a major public health threat complicating tuberculosis control programs globally. Data on rifampicin resistance (RR), which is a surrogate marker for multidrug resistance, are limited among Ethiopian tuberculosis patients. This study aimed to determine the magnitude of rifampicin-resistant Mycobacterium tuberculosis (RR-MTB) among presumptive tuberculosis patients attending St. Peter Tuberculosis Specialized Hospital, Addis Ababa, Ethiopia.

Patients and Methods

A retrospective cross-sectional study was conducted at St. Peter Tuberculosis Specialized Hospital from January 2016 to December 2018. After checking completeness of the necessary information, data of tuberculosis-presumptive cases who underwent Gene Xpert^® testing were collected from medical records using a data-extraction format prepared for this study purpose. Data were double entered and analyzed using SPSS version 20 statistical software.

Results

A total of 12,685 presumptive tuberculosis patients were included; of whom 54.5% were males and the mean age of the study participants was 40.3±18.7 years. Mycobacterium tuberculosis (MTB) was detected in 1714 participants (13.5%). Of these MTB cases, 169 cases (9.8%) were confirmed to have RR-MTB. Prevalence of MTB was relatively higher among males (15.1%, P=0.78); whereas RR-MTB was higher among females (10.3%, P=0.81). The incidence of MTB and RR-MTB was significantly associated with treatment history (P=0.042 and P=0.025), respectively. HIV infection has significantly associated with incidence of RR-MTB (P=0.032), but not with MTB (P˃0.05). Prevalence of MTB and RR-MTB had a declining trend through time, being 16.7% and 12.9%, 12.8% and 9.1%, and 12.2% and 7.9% in 2016, 2017 and 2018, respectively.

Conclusion

This study showed a decreasing trend of both MTB and RR-MTB from 2016 to 2018 in an MTB, MDR-MTB, and TB/HIV co-infection high-burden setting, Addis Ababa, Ethiopia. Occurrence of MTB and RR-MTB was associated with treatment history. Therefore, improvement in treatment adherence of identified cases would be helpful to prevent emergence or re-emergence of MTB and RR-MTB cases.

Clinical manifestations and epidemiology of adolescent tuberculosis in Ukraine

Background

During adolescence, childhood and adult forms of tuberculosis (TB) overlap, resulting in diverse disease manifestations. Knowing which patient characteristics are associated with which manifestations may facilitate diagnosis and enhance understanding of TB pathophysiology.

Methods

In this cross-sectional study, we included 10–19-year-olds in Ukraine's national TB registry who started TB treatment between 2015 and 2018. Using multivariable regression, we estimated associations between patient characteristics and four presentations of TB: pleural, extrathoracic, cavitary and rifampicin-resistant (RR). We also described the epidemiology of adolescent TB in Ukraine.

Results

Among 2491 adolescent TB cases, 88.4% were microbiologically confirmed. RR-TB was confirmed in 16.9% of new and 29.7% of recurrent cases. Of 88 HIV-infected adolescents, 59.1% were not on antiretroviral therapy at TB diagnosis. Among 10–14-year-olds, boys had more pleural disease (adjusted OR (aOR) 2.12, 95% CI: 1.08–4.37). Extrathoracic TB was associated with age 15–19 years (aOR 0.26, 95% CI: 0.18–0.37) and HIV (aOR 3.25, 95% CI: 1.55–6.61 in 10–14-year-olds; aOR 8.18, 95% CI: 3.58–17.31 in 15–19-year-olds). Cavitary TB was more common in migrants (aOR 3.53, 95% CI: 1.66–7.61) and 15–19-year-olds (aOR 4.10, 95% CI: 3.00–5.73); among 15–19-year-olds, it was inversely associated with HIV (aOR 0.32, 95% CI: 0.13–0.70). RR-TB was associated with recurrent disease (aOR 1.87, 95% CI: 1.08–3.13), urban residence (aOR 1.27, 95% CI: 1.01–1.62) and cavitation (aOR 2.98, 95% CI: 2.35–3.78).

Conclusions

Age, sex, HIV and social factors impact the presentation of adolescent TB. Preventive, diagnostic and treatment activities should take these factors into consideration.

Analysing 2491 cases of adolescent tuberculosis in Ukraine, associations were observed between four clinical presentations – cavitary, pleural, extrathoracic and rifampicin-resistant TB – and age, sex, HIV status, prior treatment and social factors.https://bit.ly/2XplZFt

A positively selected FBN1 missense variant reduces height in Peruvian individuals

On average, Peruvian individuals are among the shortest in the world¹. Here we show that Native American ancestry is associated with reduced height in an ethnically diverse group of Peruvian individuals, and identify a population-specific, missense variant in the FBN1 gene (E1297G) that is significantly associated with lower height. Each copy of the minor allele (frequency of 4.7%) reduces height by 2.2 cm (4.4 cm in homozygous individuals). To our knowledge, this is the largest effect size known for a common height-associated variant. FBN1 encodes the extracellular matrix protein fibrillin 1, which is a major structural component of microfibrils. We observed less densely packed fibrillin-1-rich microfibrils with irregular edges in the skin of individuals who were homozygous for G1297 compared with individuals who were homozygous for E1297. Moreover, we show that the E1297G locus is under positive selection in non-African populations, and that the E1297 variant shows subtle evidence of positive selection specifically within the Peruvian population. This variant is also significantly more frequent in coastal Peruvian populations than in populations from the Andes or the Amazon, which suggests that short stature might be the result of adaptation to factors that are associated with the coastal environment in Peru.

GeneXpert Mycobacterium tuberculosis/rifampicin assay for molecular epidemiology of rifampicin-Resistant Mycobacterium tuberculosis in an Urban Setting of Banten province, Indonesia

Background

Tuberculosis (TB) is the fourth leading cause of death in Indonesia. In 2017, the World Health Organization (WHO) estimated that only 2% of the TB patients in Indonesia had only been tested with rapid diagnostics at the time of diagnosis, resulting in largely underdetected rifampicin-resistant TB (RR-TB). Utilization of GeneXpert Mycobacterium tuberculosis/rifampicin (MTB/RIF) assay as a point-of-care molecular assay to detect TB and RR-TB and serving its purpose in accordance with the first pillar of the WHO End-TB Strategy.

Objective

This study investigated the use of GeneXpert MTB/RIF assay to determine the molecular epidemiology of RR-TB in an urban setting of Indonesia.

Methods

All molecular epidemiological and microbiological databases were retrospectively examined from GeneXpert MTB/RIF assay results in Siloam Hospital Lippo Village. The sociodemographic characteristics and results of microbiological examinations consisting of Ziehl-Neelsen staining and GeneXpert MTB/RIF assay were analyzed.

Results

During the study period, 600 cases were registered, and GeneXpert MTB/RIF tests were done in which the tests yielded 597 (99.5%) valid results; 62.0% were male and adult of age category; of whom 29 samples (4.9%) were found to be RR-TB, 186 samples (31.2%) were RIF sensitive, and remainders were negative.

Conclusions

The results of GeneXpert MTB/RIF to be a fundamental diagnosis of RR-TB and subsequently to notify MDR-TB were satisfying and valuable in this study. This further increased and reinforced TB surveillance and national TB program to finally bring about WHO end-TB strategy one step closer in Indonesia.

Vitamin D status and risk of incident tuberculosis disease: A nested case-control study, systematic review, and individual-participant data meta-analysis

BACKGROUND

Few studies have evaluated the association between preexisting vitamin D deficiency and incident tuberculosis (TB). We assessed the impact of baseline vitamins D levels on TB disease risk.

METHODS AND FINDINGS

We assessed the association between baseline vitamin D and incident TB in a prospective cohort of 6,751 HIV-negative household contacts of TB patients enrolled between September 1, 2009, and August 29, 2012, in Lima, Peru. We screened for TB disease at 2, 6, and 12 months after enrollment. We defined cases as household contacts who developed TB disease at least 15 days after enrollment of the index patient. For each case, we randomly selected four controls from among contacts who did not develop TB disease, matching on gender and year of age. We also conducted a one-stage individual-participant data (IPD) meta-analysis searching PubMed and Embase to identify prospective studies of vitamin D and TB disease until June 8, 2019. We included studies that assessed vitamin D before TB diagnosis. In the primary analysis, we defined vitamin D deficiency as 25-(OH)D < 50 nmol/L, insufficiency as 50-75 nmol/L, and sufficiency as >75nmol/L. We estimated the association between baseline vitamin D status and incident TB using conditional logistic regression in the Lima cohort and generalized linear mixed models in the meta-analysis. We further defined severe vitamin D deficiency as 25-(OH)D < 25 nmol/L and performed stratified analyses by HIV status in the IPD meta-analysis. In the Lima cohort, we analyzed 180 cases and 709 matched controls. The adjusted odds ratio (aOR) for TB risk among participants with baseline vitamin D deficiency compared to sufficient vitamin D was 1.63 (95% CI 0.75-3.52; p = 0.22). We included seven published studies in the meta-analysis and analyzed 3,544 participants. In the pooled analysis, the aOR was 1.48 (95% CI 1.04-2.10; p = 0.03). The aOR for severe vitamin D deficiency was 2.05 (95% CI 0.87-4.87; p trend for decreasing 25-(OH)D levels from sufficient vitamin D to severe deficiency = 0.02). Among 1,576 HIV-positive patients, vitamin D deficiency conferred a 2-fold (aOR 2.18, 95% CI 1.22-3.90; p = 0.01) increased risk of TB, and the aOR for severe vitamin D deficiency compared to sufficient vitamin D was 4.28 (95% CI 0.85-21.45; p = 0.08). Our Lima cohort study is limited by the short duration of follow-up, and the IPD meta-analysis is limited by the number of possible confounding covariates available across all studies.

CONCLUSION

Our findings suggest vitamin D predicts TB disease risk in a dose-dependent manner and that the risk of TB disease is highest among HIV-positive individuals with severe vitamin D deficiency. Randomized control trials are needed to evaluate the possible role of vitamin D supplementation on reducing TB disease risk.

International collaboration among medical societies is an effective way to boost Latin American production of articles on tuberculosis

Objective:

Most studies of tuberculosis originate from high-income countries with a low incidence of tuberculosis. A review of the scientific production on tuberculosis in Latin American countries, most of which are low- or middle-income countries (some with high or intermediate tuberculosis incidence rates), would improve the understanding of public health challenges, clinical needs, and research priorities. The aims of this systematic review were to determine what has been published recently in Latin America, to identify the leading authors involved, and to quantify the impact of international collaborations.

Methods:

We used PubMed to identify relevant manuscripts on pulmonary tuberculosis (PTB), drug-resistant tuberculosis (DR-TB), or multidrug-resistant tuberculosis (MDR-TB), published between 2013 and 2018. We selected only studies conducted in countries with an annual tuberculosis incidence of ≥ 10,000 reported cases and an annual MDR-TB incidence of ≥ 300 estimated cases, including Brazil, Peru, Mexico, Colombia, and Argentina. Articles were stratified by country, type, and topic.

Results:

We identified as eligible 395 studies on PTB and 188 studies on DR/MDR-TB-of which 96.4% and 96.8%, respectively, were original studies; 35.5% and 32.4%, respectively, had an epidemiological focus; and 52.7% and 36.2%, respectively, were conducted in Brazil. The recent Latin American Thoracic Association/European Respiratory Society/Brazilian Thoracic Association collaborative project boosted the production of high-quality articles on PTB and DR/MDR-TB in Latin America.

Conclusions:

Most of the recent Latin American studies on tuberculosis were conducted in Brazil, Mexico, or Peru. Collaboration among medical societies facilitates the production of scientific papers on tuberculosis. Such initiatives are in support of the World Health Organization call for intensified research and innovation in tuberculosis.

Primary bacillary resistance in multidrug-resistant tuberculosis and predictive factors associated with cure at a referral center in São Paulo, Brazil

Objective:

To identify transmitted or primary resistance among cases of multidrug-resistant tuberculosis and predictive factors for cure in multidrug-resistant tuberculosis after the first treatment.

Method:

Descriptive study of a cohort from 2006 to 2010, in a reference unit of tuberculosis in São Paulo, Brazil. The data were obtained by the revision of medical records. Clinical criteria were used to classify transmitted and acquired resistance. Extended primary resistance was also defined, in this study, as cases initially treated with a standardized scheme, but with no therapeutic success, and the pre-treatment drug susceptibility test (DST) showed presence of resistance.

Results:

156 patients with multidrug-resistant tuberculosis and their respective sputum samples were eligible for the study. Only 7% of the patients were positive for the human immunodeficiency virus (HIV). Previous treatment occurred in 95% of the sample. The cure rate after the first treatment was 54%. The median bacteriological conversion time of those who healed was one month. Bacillary resistance was considered acquired resistance in 100 (64%) and transmitted resistance in 56 (36%). By logistic regression, patients who presented primary multidrug-resistant tuberculosis (odds ratio-OR = 6,29), without comorbidity (OR = 3,37) and with higher initial weight (OR = 1.04) were associated with cure after the first treatment.

Conclusion:

The early detection of bacillary resistance and appropriate treatment are in favor of healing. Thus, it is crucial to know exactly the primary resistance rate avoiding the use of inadequate treatments, amplification of bacillary resistance and its transmission.

Ambient air pollution exposures and risk of drug-resistant tuberculosis

BACKGROUND

Few epidemiological studies have explored the effects of air pollution on the risk of drug-resistant tuberculosis (DR-TB).

OBJECTIVE

To investigate the short and long term residential concentrations of ambient air pollutants (particulate matter <10 μm in diameter (PM₁₀) and particulate matter≤2.5 μm in diameter (PM_2.5), nitrogen dioxide (NO₂), sulfur dioxide (SO₂), ozone (O₃), and carbon monoxide (CO)) in relation to the risk of DR-TB in a typical air pollution city, Jinan city, China.

METHODS

A total of 752 new culture-confirmed TB cases reported in TB prevention and control institutions of Jinan from January 1, 2014 to December 31, 2015 were included. Average individual-level concentrations of air pollution for 5 different exposure windows, vary from 90 days to 720 days to diagnosis were estimated using measurements from monitor closest to the patient home addresses. Logistic regression model adjusted for potential confounders was employed to evaluate correlation between air pollution and DR-TB risk at different five exposure windows individually.

RESULTS

There were substantially increased mono-drug resistance and poly-drug resistance risks for ambient PM_2.5, PM₁₀, O₃, and CO exposures. High exposure to PM_2.5, PM₁₀, and CO was also significantly associated with increased incidence of multi-drug resistance (MDR) both in the single- and multi-pollutants regression models. The dominant positive associations for PM_2.5was observed at 540 days exposure, for O₃ was observed at 180 days exposure, and for PM₁₀ and CO was observed from 90 days to 540 days exposures.

CONCLUSIONS

Our finding suggest that exposure to ambient air pollution (PM_2.5, PM₁₀, O₃, and CO) are associated with increased risk of DR-TB. We provided epidemiological evidence of association between pollution exposure and mono-, poly- and multi-drug resistance.

Acquired Resistance to Antituberculosis Drugs in England, Wales, and Northern Ireland, 2000-2015

Among tuberculosis (TB) patients, acquired resistance to anti-TB drugs represents a failure in the treatment pathway. To improve diagnosis and care for patients with drug-resistant TB, we examined the epidemiology and risk factors associated with acquired drug resistance during 2000–2015 among TB patients in England, Wales, and Northern Ireland. We found acquired resistance in 0.2% (158/67,710) of patients with culture-confirmed TB. Using multivariate logistic regression, we identified the following factors associated with acquired drug resistance: having pulmonary disease; initial resistance to isoniazid, rifampin, or both; a previous TB episode; and being born in China or South Africa. Treatment outcomes were worse for patients with than without acquired resistance. Although acquired resistance is rare in the study area, certain patient groups are at higher risk. Identifying these patients and ensuring that adequate resources are available for treatment may prevent acquisition of resistance, thereby limiting transmission of drug-resistant strains of mycobacteria.

Predictor of multidrug resistant tuberculosis in southwestern part of Ethiopia: a case control study

BACKGROUND

Curable disease tuberculosis is becoming incurable or difficult to treat due to drug resistance. Multi drug resistance tuberculosis is a major health problem for less developed countries. Development of drug resistance is mainly as result of man related factors and poor lifestyle. Identifying predictors of drug resistance and working on them is the important way of reducing the expansion in high burden countries. Ethiopia is one of TB, TB/HIV, and multi-drug resistant tuberculosis (MDR-TB) high burden country globally. This study was aimed to assess predictor of MDR-TB in southwest part of Ethiopia.

METHODS

Unmatched case control study was conducted in case to control ratio of 1:1.2 in southwest part of Ethiopia. The cases were recruited from confirmed MDR-TB patient enrolled on second line treatment in Shenen Gibe Hospital (MDR-TB treatment center of the prefecture) and the controls were recruited from previously TB patients who cured or patient with smear negative at the end of treatment month during the study period in the same area. The data was collected by structured questionnaire by interview and logistic regression analyses were used to identify predictors of MDR-TB. Odds ratios with 95% CI were computed to determine the predictors.

RESULT

From the total 132 participants about 45% of them were cases. None disclosed tuberculosis infected to relatives [AOR = 3.4, 95% CI (1.2-9.8)], insufficient instruction on how to take anti-TB drug [AOR = 4.7, 95% CI (1.4-14.6)], contact history with MDR-TB [AOR = 8.5, 95% CI (2.9-25.5)], interruption of first-line anti-TB treatment for at list 1 day [AOR = 7.9, 95% CI (2.5-24.9)], and having alcohol drinking habits [AOR = 5.1, 95% CI (1.4-18.7)] were identified predictors for MDR-TB infection in study area.

CONCLUSION

TB infection disclosure status, insufficient instruction on drug usage, contact history with MDR-TB, interruption of first-line anti-TB drugs, and alcohol drinking habits were identified predictor of MDR-TB case. Therefore, early detection and proper treatment of drug susceptible TB, strengthening directly observed treatment, short-course on daily bases, community involvement, and supporting the patient to intervene identified factors is paramount.

Prevalence of pyrazinamide resistance and Wayne assay performance analysis in a tuberculosis cohort in Lima, Peru

BACKGROUND

Multidrug-resistant tuberculosis (MDR-TB) regimens often contain pyrazinamide (PZA) even if susceptibility to the drug has not been confirmed. This gap is due to the limited availability and reliability of PZA susceptibility testing.

OBJECTIVES

To estimate the prevalence of PZA resistance using the Wayne assay among TB patients in Lima, Peru, to describe characteristics associated with PZA resistance and to compare the performance of Wayne with that of BACTEC™ MGIT™ 960.

METHODS

PZA susceptibility using the Wayne assay was tested in patients diagnosed with culture-positive pulmonary TB from September 2009 to August 2012. Factors associated with PZA resistance were evaluated. We compared the performance of the Wayne assay to that of MGIT 960 in a convenience sample.

RESULTS

The prevalence of PZA resistance was 6.6% (95%CI 5.8-7.5) among 3277 patients, and 47.7% (95%CI 42.7-52.6) among a subset of 405 MDR-TB patients. In multivariable analysis, MDR-TB (OR 86.0, 95%CI 54.0-136.9) and Latin American-Mediterranean lineage (OR 3.40, 95%CI 2.33-4.96) were associated with PZA resistance. The Wayne assay was in agreement with MGIT 960 in 83.9% of samples (κ 0.66, 95%CI 0.56-0.76).

CONCLUSION

PZA resistance was detected using the Wayne assay in nearly half of MDR-TB patients in Lima. This test can inform the selection and composition of regimens, especially those dependent on additional resistance.

Feasibility of a new model for early detection of patients with multidrug-resistant tuberculosis in a developed setting of eastern China

OBJECTIVES

The poor detection rate of multidrug-resistant tuberculosis (MDR-TB) highlights the urgent need to explore new case finding model to improve the detection of MDR-TB in China. The aim of this study was to evaluate the feasibility of a new model that combines molecular diagnostics and sputum transportation for early detection of patients with MDR-TB in Zhejiang.

METHODS

From May 2014 to January 2015, TB suspects were continuously enrolled at six county-level designated TB hospitals in Zhejiang. Each patient gave three sputum samples, which were submitted to laboratory for smear microscopy, solid culture and GeneXpert. The specimens from rifampin (RIF)-resistant cases detected by GeneXpert, and positive cultures were transported from county-level to prefecture-level laboratories for line probe analysis (LPA) and drug susceptibility testing (DST). The performance and interval of MDR-TB detection of the new model were compared with those of conventional model.

RESULTS

A total of 3151 sputum specimens were collected from TB suspects. The sensitivity of GeneXpert for detecting culture-positive cases was 92.7% (405/437), and its specificity was 91.3% (2428/2659). Of 16 RIF-resistant cases detected by DST, GeneXpert could correctly identify 15 cases, yielding a sensitivity of 93.8% (15/16). The specificity of GeneXpert for detecting RIF susceptibility was 100.0% (383/383). The average interval to diagnosis of the conventional DST model was 56.5 days, ranging from 43 to 71 days, which was significantly longer than that of GeneXpert plus LPA (22.2 days, P < 0.01).

CONCLUSION

Our data demonstrate that the combination of improved molecular TB tests and sputum transportation could significantly shorten the time required for detection of MDR-TB, which will bring benefits for preventing an epidemic of MDR-TB in this high-prevalence setting.

Social determinants of therapy failure and multi drug resistance among people with tuberculosis: A review

BACKGROUND

Social determinants influence health and the development of tuberculosis (TB). However, a paucity of data is available considering the relationship of social determinants influencing therapy failure and multi drug resistance (MDR). We conducted a review investigating the relationship of common social determinants on therapy failure and MDR in people with TB.

METHODS

PubMed and SCOPUS were searched without language restrictions until February 02, 2016 for studies reporting the association between socioeconomic factors (income, education and alcohol abuse) and therapy failure or MDR-TB. The association between social determinants and outcomes was explored by pooling data with a random effects model and calculating crude and adjusted odds ratios (ORs) ±95% confidence intervals (CIs).

RESULTS

Fifty studies with 407,555 participants with TB were included. Analysis demonstrated that low income (unadjusted OR = 2.00 (95% CI: 1.69-2.38; I² = 88%; 33 studies, adjusted OR 1.77, p < 0.0001), low education (unadjusted OR 2.11, 95% CI 1.55-2.86, 26 studies, adjusted OR 1.69, p < 0.0001) and alcohol abuse (unadjusted OR = 2.43 (95% CI: 1.56-3.80, 16 studies, adjusted OR 2.13, p < 0.0001) were associated with therapy failure. Similarly, low income (unadjusted OR = 1.67; 95% CI: 1.12-2.41, p = 0.006; 14 studies, adjusted OR 2.16, p < 0.0001) and alcohol abuse (unadjusted OR = 1.88; 95% CI: 1.18-3.00, 7 studies, adjusted OR 1.43, p = 0.06) were associated with MDR-TB. Increasing age of the population was able to explain a consistent part of the heterogeneity found.

Pattern of socio-economic and health aspects among TB patients and controls

BACKGROUND

Socio-economic and health-related factors have a significant impact on tuberculosis (TB) incidence among population residing in resource-scare settings.

OBJECTIVE

To evaluate the pattern of socio-economic and health-related factors among TB patients and control in Delhi, India.

METHODS

The present cross-sectional study was performed among 893 TB patients (or cases) and 333 healthy disease-free controls. The data for the present study was obtained from several district TB centres in north, west and south Delhi. The collected data was edited, coded and statistical analysed with the help of SPSS 20.0 version.

RESULTS

Illiteracy and primary education were significant risk factors being associated with a TB. Rented housing condition had an odds ratio (OR) of 1.4 (95% confidence interval [CI]: 1.09-1.89) compared to owned housing condition. 3-5 individuals per room were 3 times more likely to be associated with a case of TB (95% CI: 2.49-4.41). Migrant individuals were 13 times more likely to be associated with a case of TB (95% CI: 8.77-19.78) in comparison to settled population. Daily consumption of non-vegetarian food also significantly contributed to case of TB with an OR of 3.4 (95% CI: 2.51-4.72). Loss of appetite and family TB served as significant health-related factors associated with TB risk.

CONCLUSION

Lower educational status, rented household, individuals per room (as a measure of overcrowding) and migratory status served as prominent risk factors for TB disease. Preference and frequency of non-vegetarian food being consumed, night sweating, weight loss, loss of appetite, earlier TB and family TB were principle health-related risk factors associated with TB disease.