Multidrug-resistant Tuberculosis Strains Research Articles

Structure based identification of novel inhibitors against ATP synthase of Mycobacterium tuberculosis: A combined in silico and in vitro study

The shortcomings of conventional tuberculosis treatments resulting from the development of drug resistance in Mycobacterium tuberculosis drive a need for the formulation of novel therapeutic agents. The diarylquinoline class of drugs such as bedaquiline was recently approved for the treatment of multidrug-resistant strains of tuberculosis, primarily targeting c and ε subunits of the ATP synthases. Yet resistance to bedaquiline has already been reported. Therefore, Rv1311 was used as the target for the identification of possible inhibitors against the M. tuberculosis. The structure of Rv1311 was predicted and common feature pharmacophore models were generated which facilitated the identification of potential inhibitors in the ZINC database. The activities of the selected molecules were compared with known inhibitors of the ATP synthase using quantitative structure–activity relationship. The ZINC classified inhibitors showed comparable predicted activities with that of known inhibitors. Furthermore, the inhibitory behavior of the studied drug molecules was experimentally determined using in vitro techniques and showed the minimum inhibitory concentration as low as 25 μM. The resulted outcomes provide a deeper insight into the structural basis of Rv1311 inhibitions and can facilitate the process of drug design against tuberculosis.

TB or not TB? That is the question regarding TB treatment in a remote provincial hospital in Solomon Islands.

Tuberculosis (TB) remains a significant public health challenge in Solomon Islands. Limited healthcare resources, geography, and sociocultural beliefs, coupled with lack of laboratory diagnostic tools, leads to diagnostic and treatment outcome uncertainty. Kirakira Hospital (KKH) is the main provincial hospital of Makira-Ulawa Province in Solomon Islands. A retrospective clinical audit of hospitalised TB patients in KKH over a 2-year period between July 2015 and July 2017 was conducted. The cost of TB treatment was estimated by calculating the total number of inpatient bed days of treatment. Data were available for 42 of 78 listed TB patients including 23 males and 19 females, and 9 children aged less than 16 years. The average age was 35 years (range 9 months - 74 years). Thirty-five of these received a chest X-ray. All patients had at least one of the following: fever, night sweats, chronic cough and haemoptysis as part of their clinical TB presentation. Thirty-six completed the full 8-week duration of intensive HRZE treatment as inpatients of KKH. The audit shows the treatment of TB consumes 15% of the current healthcare budget of Makira-Ulawa Province. TB remains a common clinical diagnosis in KKH. TB consumes 15% of the current healthcare budget of Makira-Ulawa Province. The limited capacity and data about the management of TB in Makira province mean that it is not currently possible to measure if there has been any progress towards eradicating TB in Solomon Islands. Laboratory investigations for TB available in Makira including sputum analysis and the GeneXpert are required to improve the accuracy of diagnosis and identify multidrug resistant strains of TB. This needs to be coupled with robust monitoring and data collection of both inpatients and outpatients to ensure the current treatment protocols for TB are being followed in Makira-Ulawa Province. These steps are essential if TB is to be eradicated from the provinces of Solomon Islands by 2030.

The phytochemical bergenin as an adjunct immunotherapy for tuberculosis in mice

The widespread availability and use of modern synthetic therapeutic agents have led to a massive decline in ethnomedical therapies. However, these synthetic agents often possess toxicity leading to various adverse effects. For instance, anti-tubercular treatment (ATT) is toxic, lengthy, and severely impairs host immunity, resulting in posttreatment vulnerability to reinfection and reactivation of tuberculosis (TB). Incomplete ATT enhances the risk for the generation of multidrug- or extensively drug-resistant (MDR or XDR, respectively) variants of Mycobacterium tuberculosis (M. tb), the TB-causing microbe. Therefore, a new therapeutic approach that minimizes these risks is urgently needed to combat this deadly disease and prevent future TB epidemics. Previously, we have shown that the phytochemical bergenin induces T helper 1 (Th1)- and Th17 cell-based protective immune responses and potently inhibits mycobacterial growth in a murine model of M. tb infection, suggesting bergenin as a potential adjunct agent to TB therapy. Here, we combined ATT therapy with bergenin and found that this combination reduces immune impairment and the length of treatment in mice. We observed that co-treatment with the anti-TB drug isoniazid and bergenin produces additive effects and significantly reduces bacterial loads compared with isoniazid treatment alone. The bergenin co-treatment also reduced isoniazid-induced immune impairment; promoted long-lasting, antigen-specific central memory T cell responses; and acted as a self-propelled vaccine. Of note, bergenin treatment significantly reduced the bacterial burden of a multidrug-resistant TB strain. These observations suggest that bergenin is a potent immunomodulatory agent that could be further explored as a potential adjunct to TB therapy.

Impact of bedaquiline and capreomycin on the gene expression patterns of multidrug-resistant Mycobacterium tuberculosis H37Rv strain and understanding the molecular mechanism of antibiotic resistance.

The emergence of multidrug resistance (MDR), extensively drug-resistant, and total drug-resistant Mycobacterium tuberculosis (Mtb) strains have hampered the treatment of tuberculosis (TB). Capreomycin and Bedaquiline are currently used for MDR-TB treatment. To understand the impact of these antibiotics on Mtb genes, we have curated the gene expression data where the Mtb cultures were exposed to the Bedaquiline and Capreomycin. Based on the P value cut off (<0.05) and logFC (<-0.5 and >+0.5) values, we have selected the top differentially expressed genes during the antibiotic exposures. We have observed that the top differentially expressed Mtb genes were related to universal stress genes, two-component regulatory systems, and drug efflux pumps. We have curated the Mtb gene datasets and carried out the functional over-representation analysis using the individual gene expression values. We further, constructed the gene interaction networks of antibiotic resistance genes and virulence genes of Mtb to understand the impact of the antibiotics at the molecular level and thus to understand the antimicrobial resistance and virulence patterns. Our study elucidates the impact of antibiotics on the Mtb genes at the molecular level and the positively enriched pathways, operons, and regulons data are helpful in understanding the resistance patterns in Mtb. The upregulated genes during the exposure of Bedaquiline and Capreomycin can be considered as potent drug targets for the development of new anti-TB drugs.

Recent Advances in Tuberculosis Drug Development

The emergence of drug-resistant tuberculosis is a growing disease worldwide. The lack of safe and effective drugs, together with the frequent development of adverse drug reactions could result in worse condition. Therefore, new drugs able to booster the current tuberculosis treatment regimen are urgently required. Novel drugs that are effective and safe against Mycobacterium tuberculosis are required to reduce the number of drugs and the duration of treatment in both drug-susceptible tuberculosis and multi-drug-resistant tuberculosis. Due to increased number of multidrugresistant and extensively drug-resistant strains and the ineffectiveness of the current treatment against latent tuberculosis are challenges to be overcome in future. The scenario of drug discovery becomes upsetting when it is considered that the number of new drugs does not increase proportionally to the emergence of drug resistance. In this review, we will demonstrate the recent advances in anti-tubercular drug discovery, centre of attention on the research of compounds with potent anti-tuberculosis activity against multidrug-resistant tuberculosis strains. Although, the best treatment regimen for achieving better results and preventing adverse drug reactions remains yet to be determined, with safety concerns regarding cardiac events due to QT prolongation still to be addressed. Therefore a simple and short treatment with higher efficacy, and lesser adverse drug reactions and drug-drug interaction is expected for patients with multidrug-resistant and extensively drug-resistant tuberculosis.

Spinal Tuberculosis: A Literature Review.

* Spinal tuberculosis (STB) is a common form of extrapulmonary tuberculosis (TB), accounting for 3.7% of TB cases in the United States.* The most common presentation is chronic back pain, for which the diagnosis of STB can be easily overlooked, leading to the development of neurological deficits and osseous deformities of the spine.* The risk of TB is increasing as a result of multidrug-resistant TB strains.* The first line of treatment is antitubercular medical therapy, with surgical intervention being indicated for decompression of neurological elements that have been unresponsive to medical therapy, the restoration of spinal stability, and the correction of deformity.* Early diagnosis and treatment improve the prognosis.* This review of the current literature on STB offers an insight into our experience on STB treatment at a western STB specialist hospital.

2/3D-QSAR, molecular docking and MD simulation studies of FtsZ protein targeting benzimidazoles derivatives

The development of multi-drug and extensively-drug resistant strains of Mycobacterium tuberculosis (Mtb) have encouraged to develop new anti-TB agents with a unique mechanism of action. FtsZ, an essential protein of bacterial cytokinesis, has emerged as a validated target for antibacterial therapy. This study describes the utility of benzimidazoles (BI) derivatives as potential FtsZ inhibitors. Through 2/3D QSAR (MLR) molecular modeling, new BI-inhibitors with improved activity have been designed. Statistically significant models from 2D-QSAR (r2 = 0.90, q2 = 85 and pred_r2 = 0.60) indicated that the descriptors such as SaaOcount, –ve Potential Surface Area, and SdsCHE-index modulate the activity of a molecule. Similarly, 3D-QSAR (r2 = 0.78, q2 = 0.69 and pred_r2 = 0.59) results indicated both electrostatic and steric descriptors play a pivotal role. These indications prompted us to design 223 new BI-derivatives, out of which three BI-derivatives (D-83, D-116 and D-223) have shown some promising results.

Multidrug-resistant tuberculosis (MDR-TB) strain infection in macaques results in high bacilli burdens in airways, driving broad innate/adaptive immune responses

Tuberculosis (TB) has become the most deadly infectious diseases due to epidemics of HIV/AIDS and multidrug-resistant/extensively drug-resistant TB (MDR-/XDR-TB). Although person-to-person transmission contributes to MDR-TB, it remains unknown whether infection with MDR strains resembles infection with drug-sensitive (DS) TB strains, manipulating limited or broad immune responses. To address these questions, macaques were infected with MDR strain V791 and a drug-sensitive Erdman strain of TB. MDR bacilli burdens in the airway were significantly higher than those of the Erdman control after pulmonary exposure. This productive MDR strain infection upregulated the expression of caspase 3 in macrophages/monocytes and induced appreciable innate-like effector responses of CD3-negative lymphocytes and Ag-specific γδ T-cell subsets. Concurrently, MDR strain infection induced broad immune responses of T-cell subpopulations producing Th1, Th17, Th22, and CTL cytokines. Furthermore, MDR bacilli, like the Erdman strain, were capable of inducing typical TB disease characterized by weight loss, lymphocytopenia, and severe TB lesions. For the first time, our results suggest that MDR-TB infection acts like DS to induce high bacterial burdens in the airway (transmission advantage), innate/adaptive immune responses, and disease processes. Because nonhuman primates are biologically closer to humans than other species, our data may provide useful information for predicting the effects of primary MDR strain infection after person-to-person transmission. The findings also support the hypothesis that a vaccine or host-directed adjunctive modality that is effective for drug-sensitive TB is likely to also impact MDR-TB.

Ciprofloxacin–Isatin Hybrids and Their Antimycobacterial Activities

A series of diethylene glycol tethered ciprofloxacin–isatin hybrids 5a–j were designed, synthesized, and evaluated for their in vitro antimycobacterial activity against both drug‐sensitive and multidrug‐resistant (MDR) Mycobacterium tuberculosis strains in this paper. The preliminary results revealed that all hybrids with greater lipophilicity than the parent ciprofloxacin displayed considerable activity against the tested strains with minimum inhibitory concentration (MIC) in a range of 1.56–64 μg/mL. In particular, hybrid 5f (MIC: 1.56 and 2 μg/mL) with low cytotoxicity in VERO cell line was comparable with the parent ciprofloxacin (MIC: 0.78 and 2 μg/mL) against M. tuberculosis H37Rv and MDR tuberculosis strains and ≥16‐fold more potent than isoniazid and rifampicin (MIC: &gt;128 and 32 μg/mL, respectively) against MDR tuberculosis, suggesting that it may serve as a new and promising candidate for further study.

Evaluation of the GenoType MTBDRplus and MTBDRsl for the detection of drug-resistant Mycobacterium tuberculosis on isolates from Beijing, China.

BackgroundThe incidence of tuberculosis (TB), especially multidrug-resistant TB (MDR-TB) and extensively drug-resistant TB (XDR-TB), continues to increase alarmingly worldwide. Molecular line probe assays (LPAs) are endorsed by the World Health Organization for the fast detection of MDR-TB and XDR-TB. The aim of this study was to evaluate the performance of LPAs in China.MethodsWe analyzed MDR-TB and XDR-TB in 96 isolates from Beijing by using culture-based drug susceptibility testing (DST) and LPAs to compare the detection rate of the two methods.ResultsCompared to phenotypic DST, the GenoType® MTBDRplus and MTBDRsl, respectively, showed a sensitivity of 98.7% and a specificity of 88.9% for detection of rifampicin resistance, 82.1% and 94.4% for isoniazid, 89.7% and 94.4% for levofloxacin, 60.0% and 98.7% for amikacin/capreomycin, and 57.5% and 98.2% for ethambutol. The sensitivity and specificity of LPAs, respectively, were 80.8% and 100% for MDR-TB and 50.0% and 97.6% for XDR-TB. Mutations in codon S531L of the rpoB gene and S315T1 of the KatG gene were dominated in MDR-TB strains. The most frequently observed mutations were in codon A90V of the gyrA gene, A1401G of the rrs gene, and M306V of the embB gene, according to the MTBDRsl results.ConclusionOur study showed that, in combination with phenotypic DST, application of the LPAs might be an efficient and reliable supplementary DST assay for rapid susceptibility screening of MDR-TB and XDR-TB. Using LPAs in countries with high MDR/XDR burden allows for appropriate and timely treatment, which will reduce transmission rates and morbidity, and improve treatment outcomes in patients.

Drug Susceptibility Profile of Mycobacterium tuberculosis Isolated from Patients Visiting National Tuberculosis Centre, Nepal

Objectives: The objective of this study was to assess drug susceptibility pattern of Mycobacterium tuberculosis (MTB).&#x0D; Methods: This cross-sectional study was carried out among 145 clinically suspected and previously treated pulmonary tuberculosis patients visiting National Tuberculosis Centre, Bhaktapur, Nepal. After obtaining written informed consent, questionnaire was administered and sputum samples were collected from each patient. Each sample was subjected to Ziehl-Neelsen (ZN) staining and cultured on Lowenstein Jensen (LJ) medium at 37ºC for 8 weeks. MTB isolates were identified by growth rate and colony morphology, confirmed by biochemical tests and drug susceptibility testing (DST) of identified isolates was performed by proportion method.&#x0D; Results: A total of 49.7% (n=72) sputum samples were positive for MTB by culture and 46.9% (n=68) were positive by ZN staining. Among culture positive isolates of MTB (n= 72), 25% (n=18) were resistant to at least one drug. The prevalence of multi drug resistant tuberculosis (MDR-TB) was 15.3% (n=11) of which 5.56% (n=4) were resistant to rifampicin (RIF) only, 1.39% (n= 1) were resistant to isoniazid (INH) only. Out of 18 resistant isolates, 61.1% (n=11) were resistant to both RIF and INH, 21.43% (n=3) resistant to INH were susceptible to RIF and 26.67% (n=4) resistant to RIF were susceptible to INH. Smoking (P=0.001) and coughing (P=0.009) were statistically significant with isolation of MTB.&#x0D; Conclusion: Since the prevalence of MDR-TB was high, MDR-TB strains should be identified in order to initiate second line treatment.

Structure-Based Design of MptpB Inhibitors That Reduce Multidrug-Resistant Mycobacterium tuberculosis Survival and Infection Burden in Vivo.

Mycobacterium tuberculosis protein-tyrosine-phosphatase B (MptpB) is a secreted virulence factor that subverts antimicrobial activity in the host. We report here the structure-based design of selective MptpB inhibitors that reduce survival of multidrug-resistant tuberculosis strains in macrophages and enhance killing efficacy by first-line antibiotics. Monotherapy with an orally bioavailable MptpB inhibitor reduces infection burden in acute and chronic guinea pig models and improves the overall pathology. Our findings provide a new paradigm for tuberculosis treatment.

Relapse Versus Reinfection of Recurrent Tuberculosis Patients in a National Tuberculosis Specialized Hospital in Beijing, China.

Tuberculosis (TB) recurrence can result from either relapse of an original infection or exogenous reinfection with a new strain of Mycobacterium tuberculosis (MTB). The aim of this study was to assess the roles of relapse and reinfection among recurrent TB cases characterized by a high prevalence rate of drug-resistant TB within a hospital setting. After 58 paired recurrent TB cases were genotyped to distinguish relapse from reinfection, 37 (63.8%) were demonstrated to be relapse cases, while the remaining 21 were classified as reinfection cases. Statistical analysis revealed that male gender was a risk factor for TB reinfection, odds ratios and 95% confidence interval (OR [95% CI]: 4.188[1.012–17.392], P = 0.049). Of MTB isolates obtained from the 37 relapse cases, 11 exhibited conversion from susceptible to resistance to at least one antibiotic, with the most frequent emergence of drug resistance observed to be levofloxacin. For reinfection cases, reemergence of rifampicin-resistant isolates harboring double gene mutations, of codon 531 of rpoB and codon 306 of embB, were observed. In conclusion, our data demonstrate that relapse is a major mechanism leading to TB recurrence in Beijing Chest Hospital, a national hospital specialized in TB treatment. Moreover, male patients are at higher risk for reinfection. The extremely high rate of multidrug-resistant tuberculosis (MDR-TB) among reinfection cases reflects more successful transmission of MDR-TB strains versus non-resistant strains overall.

Investigating spillover of multidrug-resistant tuberculosis from a prison: a spatial and molecular epidemiological analysis

BackgroundCongregate settings may serve as institutional amplifiers of tuberculosis (TB) and multidrug-resistant tuberculosis (MDR-TB). We analyze spatial, epidemiological, and pathogen genetic data prospectively collected from neighborhoods surrounding a prison in Lima, Peru, where inmates experience a high risk of MDR-TB, to investigate the risk of spillover into the surrounding community.MethodsUsing hierarchical Bayesian statistical modeling, we address three questions regarding the MDR-TB risk: (i) Does the excess risk observed among prisoners also extend outside the prison? (ii) If so, what is the magnitude, shape, and spatial range of this spillover effect? (iii) Is there evidence of additional transmission across the region?ResultsThe region of spillover risk extends for 5.47 km outside of the prison (95% credible interval: 1.38, 9.63 km). Within this spillover region, we find that nine of the 467 non-inmate patients (35 with MDR-TB) have MDR-TB strains that are genetic matches to strains collected from current inmates with MDR-TB, compared to seven out of 1080 patients (89 with MDR-TB) outside the spillover region (p values: 0.022 and 0.008). We also identify eight spatially aggregated genetic clusters of MDR-TB, four within the spillover region, consistent with local transmission among individuals living close to the prison.ConclusionsWe demonstrate a clear prison spillover effect in this population, which suggests that interventions in the prison may have benefits that extend to the surrounding community.

In vitro bactericidal activity of 3-Cinnamoyl-4-hydroxy-6-methyl-2H-pyran-2-ones (CHPs) against drug susceptible and multidrug resistant strains of Mycobacterium tuberculosis

In vitro bactericidal activity of 3-Cinnamoyl-4-hydroxy-6-methyl-2H-pyran-2-ones (CHPs) against drug susceptible and multidrug resistant strains of Mycobacterium tuberculosis

Have compensatory mutations facilitated the current epidemic of multidrug-resistant tuberculosis?

Compensatory mutations have been suggested to promote multidrug-resistant tuberculosis (MDR-TB) transmission, but their role in facilitating the recent transmission of MDR-TB is unclear. To investigate the epidemiological significance of compensatory mutations, we analyzed a four-year population-based collection of MDR-TB strains from Shanghai (the most populous city in China) and 1346 published global MDR-TB strains. We report that MDR-TB strains with compensatory mutations in the rpoA, rpoB, or rpoC genes were neither more frequently clustered nor found in larger clusters than those without compensatory mutations. Our results suggest that compensatory mutations are not a major contributor to the current epidemic of MDR-TB.

Management of Multidrug-Resistant Tuberculosis.

Drug-resistant strains of Mycobacterium tuberculosis pose a major threat to global tuberculosis control. Despite the availability of curative antituberculosis therapy for nearly half a century, inappropriate and inadequate treatment of tuberculosis, as well as unchecked transmission of M. tuberculosis, has resulted in alarming levels of drug-resistant tuberculosis. The World Health Organization (WHO) estimates that there were 600,000 cases of multidrug-resistant tuberculosis (MDR-TB)/rifampin-resistant (RR) tuberculosis in 2016, defined as strains that are resistant to at least isoniazid and rifampicin. Globally, WHO estimates that 4.1% of new tuberculosis cases and 19% of retreatment cases have MDR-TB. By the end of 2016, 123 countries had reported at least one case of extensively drug-resistant strains, which are MDR-TB strains that have acquired additional resistance to fluoroquinolones and at least one second-line injectable. It is estimated that only 22% of all MDR-TB cases are currently receiving therapy. This article reviews the management of MDR/RR-TB and updates recommendations regarding the use of shorter course regimens and new drugs.

The Potential of Ganoderma Lucidum as Antimicrobial Agent for Multidrug- Resistant Mycobacterium Tuberculosis

Background: The problem of bacterial resistance of Mycobacterium tuberculosis should be solved by seeking for alternative substances that potentially inhibit the growth or kill the bacteria. Ganoderma lucidum is one type of fungus which is potential to be an antimicrobial agent. This study aimed to determine the potential of G. lucidum on inhibiting the growth of multidrug-resistant bacteria of M. tuberculosis in vitro. Methods: This study used a solid dilution method to test the extract of G. lucidum as an antibacterial agent. Results and Conclusion: Results showed that all strains of multidrug-resistant tuberculosis (MDR-Tb) gave similar responses to G. lucidum extract at various concentrations. The bacteria did not grow on the medium containing G. lucidum extract at the smallest concentration of 12.5%, as well as concentrations of 25% and 50%. Ganoderma lucidum can be used as one of the alternatives for MDR-Tb drugs in the future.

Genetic diversity of drug and multidrug-resistant Mycobacterium tuberculosis circulating in Veracruz, Mexico.

BackgroundMexico is one of the most important contributors of drug and multidrug-resistant tuberculosis in Latin America; however, knowledge of the genetic diversity of drug-resistant tuberculosis isolates is limited.MethodsIn this study, the genetic structure of 112 Mycobacterium tuberculosis strains from the southeastern Mexico was determined by spoligotyping and 24-loci MIRU-VNTRs.FindingsThe results show eight major lineages, the most of which was T1 (24%), followed by LAM (16%) and H (15%). A total of 29 (25%) isolates were identified as orphan. The most abundant SITs were SIT53/T1 and SIT42/LAM9 with 10 isolates each and SIT50/H3 with eight isolates. Fifty-two spoligotype patterns, twenty-seven clusters and ten clonal complexes were observed, demonstrating an important genetic diversity of drug and multidrug-resistant tuberculosis isolates in circulation and transmission level of these aggravated forms of tuberculosis. Being defined as orphan or as part of an orphan cluster, was a risk factor for multidrug resistant-tuberculosis (OR 2.5, IC 1.05–5.86 and OR 3.3, IC 1–11.03, respectively). Multiple correspondence analyses showed association of some clusters and SITs with specific geographical locations.ConclusionsOur study provides one of the most detailed description of the genetic structure of drug and multidrug-resistant tuberculosis strains in southeast Mexico, establishing for the first time a baseline of the genotypes observed in resistant isolates circulating, however further studies are required to better elucidate the genetic structure of tuberculosis in region and the factors that could be participating in their dispersion.

New hydrazides derivatives of isoniazid against Mycobacterium tuberculosis: Higher potency and lower hepatocytotoxicity

Tuberculosis (TB) is one of the leading causes of death worldwide. The emergence of multi-drug resistant strains of Mycobacterium tuberculosis (Mtb) and TB-HIV co-infection are major public health challenges. The anti-TB drugs of first choice were developed more than 4 decades ago and present several adverse effects, making the treatment of TB even more complicated and the development of new chemotherapeutics for this disease imperative. In this work, we synthesized two series of new acylhydrazides and evaluated their activity against different strains of Mtb. Derivatives of isoniazid (INH) showed important anti-Mtb activity, some being more potent than all anti-TB drugs of first choice. Moreover, three compounds proved to be more potent than INH against resistant Mtb. The Ames test showed favorable results for two of these substances compared to INH, one of which presented expressly lower toxicity to HepG2 cells than that of INH. This result shows that this compound has the potential to overcome one of the main adverse effects of this drug.