The anti-leprosy drug clofazimine reduces polyQ toxicity through activation of PPARγ.

BACKGROUND: PolyQ diseases are autosomal dominant neurodegenerative disorders caused by the expansion of CAG repeats. While of slow progression, these diseases are ultimately fatal and lack effective therapies. METHODS: A high-throughput chemical screen was conducted to identify drugs that lower the toxicity of a protein containing the first exon of Huntington's disease (HD) protein huntingtin (HTT) harbouring 94 glutamines (Htt-Q94). Candidate drugs were tested in a wide range of in vitro and in vivo models of polyQ toxicity. FINDINGS: The chemical screen identified the anti-leprosy drug clofazimine as a hit, which was subsequently validated in several in vitro models. Computational analyses of transcriptional signatures revealed that the effect of clofazimine was due to the stimulation of mitochondrial biogenesis by peroxisome proliferator-activated receptor gamma (PPARγ). In agreement with this, clofazimine rescued mitochondrial dysfunction triggered by Htt-Q94 expression. Importantly, clofazimine also limited polyQ toxicity in developing zebrafish and neuron-specific worm models of polyQ disease. INTERPRETATION: Our results support the potential of repurposing the antimicrobial drug clofazimine for the treatment of polyQ diseases. FUNDING: A full list of funding sources can be found in the acknowledgments section.

Whole blood transcriptomics reveals the enrichment of neutrophil activation pathways during erythema nodosum leprosum reaction.

Introduction: Patients with the multibacillary form of leprosy can develop reactional episodes of acute inflammation, known as erythema nodosum leprosum (ENL), which are characterized by the appearance of painful cutaneous nodules and systemic symptoms. Neutrophils have been recognized to play a role in the pathogenesis of ENL, and recent global transcriptomic analysis revealed neutrophil-related processes as a signature of ENL skin lesions. Methods: In this study, we expanded this analysis to the blood compartment, comparing whole blood transcriptomics of patients with non-reactional lepromatous leprosy at diagnosis (LL, n=7) and patients with ENL before administration of anti-reactional treatment (ENL, n=15). Furthermore, a follow-up study was performed with patients experiencing an ENL episode at the time of diagnosis and after 7 days of thalidomide treatment (THAL, n=10). Validation in an independent cohort (ENL=8; LL=7) was performed by RT-qPCR. Results: An enrichment of neutrophil activation and degranulation-related genes was observed in the ENL group, with the gene for the neutrophil activation marker CD177 being the most enriched gene of ENL episode when compared to its expression in the LL group. A more pro-inflammatory transcriptome was also observed, with increased expression of genes related to innate immunity. Validation in an independent cohort indicated that S100A8 expression could discriminate ENL from LL. Supernatants of blood cells stimulated in vitro with Mycobacterium leprae sonicate showed higher levels of CD177 compared to the level of untreated cells, indicating that the leprosy bacillus can activate neutrophils expressing CD177. Of note, suggestive higher CD177 protein levels were found in the sera of patients with severe/moderate ENL episodes when compared with patients with mild episodes and LL patients, highlighting CD177 as a potential systemic marker of ENL severity that deserves future confirmation. Furthermore, a follow-up study was performed with patients at the time of ENL diagnosis and after 7 days of thalidomide treatment (THAL, n=10). Enrichment of neutrophil pathways was sustained in the transcriptomic profile of patients undergoing treatment; however, important immune targets that might be relevant to the effect of thalidomide at a systemic level, particularly NLRP6 and IL5RA, were revealed. Discussion: In conclusion, our study reinforces the key role played by neutrophils in ENL pathogenesis and shed lights on potential diagnostic candidates and novel therapeutic targets that could benefit patients with leprosy.

Effect of multidrug therapy on the prognosis of Mycobacterium avium complex pulmonary disease.

Multidrug therapy for Mycobacterium avium complex pulmonary disease (MAC-PD) results in negative sputum cultures. However, the prognostic value of this treatment approach remains unclear. This study aimed to clarify whether multidrug therapy reduces the incidence of events related to MAC-PD and improves the mortality rate. Patients who met the diagnostic criteria for MAC-PD at our hospital between 2003 and 2019 were retrospectively evaluated using medical records. Events related to MAC-PD were defined as hospitalisation for haemoptysis or respiratory infection and the development of chronic respiratory failure. There were 90 and 108 patients in the multidrug and observation groups, respectively. The median observation period was 86 months. Intergroup differences in body mass index, proportion of patients with cavities, and erythrocyte sedimentation rate were not significant. However, the observation group was older with a higher mean age (multidrug group: 62 years, observation group: 69 years; P < 0.001) and had a higher proportion of male patients (multidrug group: 13/90 [14.4%], observation group: 35/108 [32.4%]; P < 0.01). Furthermore, intergroup differences in the incidence of events related to MAC-PD (multidrug group: 26.69/1000 person-years, observation group: 25.49/1000 person-years), MAC-PD-associated mortality rate (multidrug group: 12.13/1000 person-years, observation group: 12.74/1000 person-years), and total mortality (multidrug group: 24.26/1000 person-years, observation group: 29.50/1000 person-years) were not significant. Many patients relapse even after multidrug therapy, and our findings suggest that multidrug therapy has no effect in preventing the onset of respiratory events or prolonging life expectancy.

Gastric cancer mesenchymal stem cells promote tumor glycolysis and chemoresistance by regulating B7H3 in gastric cancer cells.

Despite surgical treatment combined with multidrug therapy having made some progress, chemotherapy resistance is the main cause of recurrence and death of gastric cancer (GC). Gastric cancer mesenchymal stem cells (GCMSCs) have been reported to be correlated with the limited efficacy of chemotherapy in GC, but the mechanism of GCMSCs regulating GC resistance needs to be further studied. The gene set enrichment analysis (GSEA) was performed to explore the glycolysis-related pathways heterogeneity across different cell subpopulations. Glucose uptake and lactate production assays were used to evaluate the importance of B7H3 expression in GCMSCs-treated GC cells. The therapeutic efficacy of oxaliplatin (OXA) and paclitaxel (PTX) was determined using CCK-8 and colony formation assays. Signaling pathways altered by GCMSCs-CM were revealed by immunoblotting. The expression of TNF-α in GCMSCs and bone marrow mesenchymal stem cells (BMMSCs) was detected by western blot analysis and qPCR. Our results showed that the OXA and PTX resistance of GC cells were significantly enhanced in the GCMSCs-CM treated GC cells. Acquired OXA and PTX resistance was characterized by increased cell viability for OXA and PTX, the formation of cell colonies, and decreased levels of cell apoptosis, which were accompanied by reduced levels of cleaved caspase-3 and Bax expression, and increased levels of Bcl-2, HK2, MDR1, and B7H3 expression. Blocking TNF-α in GCMSCs-CM, B7H3 knockdown or the use of 2-DG, a key enzyme inhibitor of glycolysis in GC cells suppressed the OXA and PTX resistance of GC cells that had been treated with GCMSCs-CM. This study shows that GCMSCs-CM derived TNF-α could upregulate the expression of B7H3 of GC cells to promote tumor chemoresistance. Our results provide a new basis for the treatment of GC.

Novel mutations found in Mycobacterium leprae DNA repair gene nth from central India.

INTRODUCTION: The importance of DNA repair enzymes in maintaining genomic integrity is highlighted by the hypothesis that DNA damage by reactive oxygen/nitrogen species produced inside the host cell is essential for the mutagenesis process. Endonuclease III (Nth), formamidopyrimide (Fpg) and endonuclease VIII (Nei) DNA glycosylases are essential components of the bacterial base excision repair process. Mycobacterium leprae lost both fpg/nei genes during the reductive evolution event and only has the nth (ML2301) gene. This study aims to characterize the mutations in the nth gene of M. leprae strains and explore its correlation with drug-resistance. METHOD: A total of 91 M. leprae positive DNA samples extracted from skin biopsy samples of newly diagnosed leprosy patients from NSCB Hospital Jabalpur were assessed for the nth gene as well as drug resistance-associated loci of the rpoB, gyrA and folP1 genes through PCR followed by Sanger sequencing. RESULTS: Of these 91 patients, a total of two insertion frameshift mutations, two synonymous and seven nonsynonymous mutations were found in nth in seven samples. Sixteen samples were found to be resistant to ofloxacin and one was found to be dapsone resistant as per the known DRDR mutations. No mutations were found in the rpoB region. Interestingly, none of the nth mutations were identified in the drug-resistant associated samples. CONCLUSION: The in-silico structural analysis of the non-synonymous mutations in the Nth predicted five of them were to be deleterious. Our results suggest that the mutations in the nth gene may be potential markers for phylogenetic and epidemiological studies.

High frequency of ofloxacin resistance patterns of Mycobacterium leprae from India: An indication to revisit second line anti-leprosy treatment regimen.

OBJECTIVES: Drug resistance in leprosy is an emerging concern, leading to treatment failures, recurrences, and potential spread of resistant Mycobacterium leprae in the community. In this study, we aimed to assess drug resistance prevalence and patterns amongst leprosy patients at a tertiary care referral hospital in India. METHODS: Mutations in drug resistance determining regions for dapsone, rifampicin, and ofloxacin of the M. leprae genome in DNA extracted from skin biopsies of 136 leprosy patients (treatment-naive = 67, with persistent skin lesions = 35, with recurrence = 34) were analysed by polymerase chain reaction followed by Sanger sequencing. Wild-type strain (Thai-53) was used as a reference strain. RESULTS: Resistance mutations were identified in a total of 23 patients, constituting 16.9% of the cohort. Within this subset of 23 cases, resistance to ofloxacin was observed in 17 individuals (12.5%), while resistance to both dapsone and rifampicin was detected in three patients each (2.2% for both). The occurrence of ofloxacin resistance showed minimal disparity between recurrent and treatment-naive cases, at 17.6% and 16.4%, respectively. Dapsone resistance emerged in two treatment-naive cases and one case with persistent skin lesions. Notably, none of the treatment-naive cases or those with recurrence/relapse exhibited rifampicin resistance. Subsequently, no statistically significant correlation was identified between other clinical variables and the presence of antimicrobial resistance. CONCLUSIONS: The occurrence of resistance to the current multidrug therapy regimen (specifically dapsone and rifampicin) and to ofloxacin, a secondary antileprosy medication in M. leprae, represents a concerning scenario. This calls for an expansion towards bactericidal drug options and the establishment of robust surveillance for drug resistance in countries burdened with high leprosy rates. Moreover, the introduction of stringent antimicrobial stewardship initiatives is imperative. As a single centre study, it represents a limited, cross-sectional view of the real situation in the field.

Cocrystallizing and Codelivering Complementary Drugs to Multidrugresistant Tuberculosis Bacteria in Perfecting Multidrug Therapy.

Bacteria cells exhibit multidrug resistance in one of two ways: by raising the genetic expression of multidrug efflux pumps or by accumulating several drug-resistant components in many genes. Multidrug-resistive tuberculosis bacteria are treated by multidrug therapy, where a few certain antibacterial drugs are administered together to kill a bacterium jointly. A major drawback of conventional multidrug therapy is that the administration never ensures the reaching of different drug molecules to a particular bacterium cell at the same time, which promotes growing drug resistivity step-wise. As a result, it enhances the treatment time. With additional tabletability and plasticity, the formation of a cocrystal of multidrug can ensure administrating the multidrug chemically together to a target bacterium cell. With properly maintaining the basic philosophy of multidrug therapy here, the synergistic effects of drug molecules can ensure killing the bacteria, even before getting the option to raise the drug resistance against them. This can minimize the treatment span, expenditure and drug resistance. A potential threat of epidemic from tuberculosis has appeared after the Covid-19 outbreak. An unwanted loop of finding molecules with the potential to kill tuberculosis, getting their corresponding drug approvals, and abandoning the drug after facing drug resistance can be suppressed here. This perspective aims to develop the universal drug regimen by postulating the principles of drug molecule selection, cocrystallization, and subsequent harmonisation within a short period to address multidrug-resistant bacteria.

Inhibitory effect of natural compounds on Dihydropteroate synthase of Mycobacterium leprae: Molecular dynamic study.

Leprosy is a chronic infectious disease caused by a bacillus, Mycobacterium leprae. According to official data from 139 countries in the 6 WHO Regions, there were 127558 new leprosy cases worldwide in 2020. Leprosy mainly affects the skin, the peripheral nerves, mucosa of the upper respiratory tract, and the eyes. If this disease is left untreated, can harm the skin, nerves, limbs, eyes, and skin permanently. The disease is curable with multidrug therapy. Over a period of time Mycobacterium leprae has become resistant to these drugs. Therefore, new therapeutic molecules are warranted. This study was aimed to carry out the in-silico analysis to determine the inhibitory effect of natural compounds on Dihydropteroate synthase (DHPS) of Mycobacterium leprae. The DHPS is a key enzyme in the folate biosynthesis pathway in M. leprae and acts as a competitive inhibitor of PABA. The 3D structure of DHPS protein was modeled using homology modeling and was validated. Molecular docking and simulation along with other in-silico methods were employed to determine the inhibitory effect of ligand molecules towards DHPS target protein. Results revealed ZINC03830554 molecule as a potential inhibitor of DHPS. Binding experiments and bioassays utilizing this strong inhibitor molecule against purified DHPS protein are necessary to validate these early findings.Communicated by Ramaswamy H. Sarma.

Critical observation of WHO recommended multidrug therapy on the disease leprosy through mathematical study.

Leprosy is a skin disease and it is characterized by a disorder of the peripheral nervous system which occurs due to the infection of Schwann cells. In this research article, we have formulated a four-dimensional ODE-based mathematical model which consists of the densities of healthy Schwann cells, infected Schwann cells, M. leprae bacteria, and the concentration of multidrug therapy (MDT). This work primarily aims on exploring the dynamical changes and interrelations of the system cell populations during the disease progression. Also, evaluating a critical value of the drug efficacy rate of MDT remains our key focus in this article so that a safe drug dose regimen for leprosy can be framed more effectively and realistically. We have examined the stability scenario of different equilibria and the occurrence of Hopf-bifurcation for the densities of our system cell populations with respect to the drug efficacy rate of MDT to gain insight on the precise impact of the efficiency rate on both the infected Schwann cell and the bacterial populations. Also, a necessary transversality condition for the occurrence of the bifurcation has been established. Our analytical and numerical investigations in this research work precisely explores that the process of demyelination, nerve regeneration, and infection of the healthy Schwann cells are the three most crucial factors in the leprosy pathogenesis and to control the M. leprae-induced infection of Schwann cells successfully, a more flexible version of MDT regime with efficacy rate varying in the range η∈(0.025,0.059) for 100-120 days in PB cases and 300 days in MB cases obtained in this research article should be applied. All of our analytical outcomes have been verified through numerical simulations and compared with some existing clinical findings.

An Overview of Treatment Guidelines and Methods of Synthesis of Drugs Used in Leprosy Chemotherapy.

Leprosy is a Neglected Tropical Disease (NTDs) caused by Mycobacterium leprae (M. leprae). The treatment is considered effective, however, the high dose Multidrug Therapy (MDT) for a long period and its adverse effects result in the abandonment of the treatment by patients. Indeed, antimicrobial resistance is still an obstacle that must be overcome in the treatment of leprosy. In the present article, we reviewed the WHO guidelines for the chemotherapy of leprosy and the methods of synthesis of these drugs.

Drug Resistance (Dapsone, Rifampicin, Ofloxacin) and Resistance-Related Gene Mutation Features in Leprosy Patients: A Systematic Review and Meta-Analysis.

Dapsone (DDS), Rifampicin (RIF) and Ofloxacin (OFL) are drugs recommended by the World Health Organization (WHO) for the treatment of leprosy. In the context of leprosy, resistance to these drugs occurs mainly due to mutations in the target genes (Folp1, RpoB and GyrA). It is important to monitor antimicrobial resistance in patients with leprosy. Therefore, we performed a meta-analysis of drug resistance in Mycobacterium leprae and the mutational profile of the target genes. In this paper, we limited the study period to May 2022 and searched PubMed, Web of Science (WOS), Scopus, and Embase databases for identified studies. Two independent reviewers extracted the study data. Mutation and drug-resistance rates were estimated in Stata 16.0. The results demonstrated that the drug-resistance rate was 10.18% (95% CI: 7.85-12.51). Subgroup analysis showed the highest resistance rate was in the Western Pacific region (17.05%, 95% CI:1.80 to 13.78), and it was higher after 2009 than before [(11.39%, 7.46-15.33) vs. 6.59% (3.66-9.53)]. We can conclude that the rate among new cases (7.25%, 95% CI: 4.65-9.84) was lower than the relapsed (14.26%, 95 CI%: 9.82-18.71). Mutation rates of Folp1, RpoB and GyrA were 4.40% (95% CI: 3.02-5.77), 3.66% (95% CI: 2.41-4.90) and 1.28% (95% CI: 0.87-1.71) respectively, while the rate for polygenes mutation was 1.73% (0.83-2.63). For further analysis, we used 368 drug-resistant strains as research subjects and found that codons (Ser, Pro, Ala) on RpoB, Folp1 and GyrA are the most common mutation sites in the determining region (DRDR). In addition, the most common substitution patterns of Folp1, RpoB, and GyrA are Pro→Leu, Ser→Leu, and Ala→Val. This study found that a higher proportion of patients has developed resistance to these drugs, and the rate has increased since 2009, which continue to pose a challenge to clinicians. In addition, the amino acid alterations in the sequence of the DRDR regions and the substitution patterns mentioned in the study also provide new ideas for clinical treatment options.

Global prevalence of resistance to rifampicin in Mycobacterium leprae: A meta-analysis.

OBJECTIVES: As the only bactericidal drug in multidrug therapy is rifampicin, monitoring of antimicrobial resistance is important in leprosy patients. Therefore, we conducted a meta-analysis on the resistance of Mycobacterium leprae (M. leprae) to rifampicin and estimated drug resistance in different therapeutic states and regions. METHODS: Embase, Medline, PubMed, and Web of Science were searched to identify studies between 1 January 1993 and 1 January 2022. Two independent reviewers extracted study data. Pooled cumulative incidences were computed using random-effects meta-analyses. RESULTS: We included 32 papers describing the resistance of M. leprae to rifampicin (pooled cumulative incidences, 11% [95% confidence interval {CI}, 7% to 15%]). Therapeutic states and regional distribution were obtained for subgroup analyses. A total of 51 of 1135 new cases (pooled incidence, 10% [95% CI, 5% to 16%]) and 81 of 733 relapsed cases (pooled incidence, 20% [95% CI, 13% to 27%]) had rifampicin resistance. A total of 139 participants, including 11 patients with rifampicin resistance (pooled incidence, 42% [95% CI, -21% to 105%]), were nonresponsive and intractable cases. The incidence of rifampicin resistance was highest in the Western Pacific (pooled incidence, 21% [95% CI, 13% to 29%]) and lowest in the Americas (pooled incidence, 4% [95% CI, 1% to 7%]). CONCLUSIONS: Drug resistance testing and a robust and rigorous surveillance system are recommended to detect the prevalence of drug resistance in leprosy.

Gene expression patterns associated with multidrug therapy in multibacillary leprosy.

Multidrug therapy (MDT) has been successfully used in the treatment of leprosy. However, although patients are cured after the completion of MDT, leprosy reactions, permanent disability, and occasional relapse/reinfection are frequently observed in patients. The immune system of multibacillary patients (MB) is not able to mount an effective cellular immune response against M. leprae. Consequently, clearance of bacilli from the body is a slow process and after 12 doses of MDT not all MB patients reduce bacillary index (BI). In this context, we recruited MB patients at the uptake and after 12-month of MDT. Patients were stratified according to the level of reduction of the BI after 12 doses MDT. A reduction of at least one log in BI was necessary to be considered a responder patient. We evaluated the pattern of host gene expression in skin samples with RNA sequencing before and after MDT and between samples from patients with or without one log reduction in BI. Our results demonstrated that after 12 doses of MDT there was a reduction in genes associated with lipid metabolism, inflammatory response, and cellular immune response among responders (APOBEC3A, LGALS17A, CXCL13, CXCL9, CALHM6, and IFNG). Also, by comparing MB patients with lower BI reduction versus responder patients, we identified high expression of CDH19, TMPRSS4, PAX3, FA2H, HLA-V, FABP7, and SERPINA11 before MDT. From the most differentially expressed genes, we observed that MDT modulates pathways related to immune response and lipid metabolism in skin cells from MB patients after MDT, with higher expression of genes like CYP11A1, that are associated with cholesterol metabolism in the group with the worst response to treatment. Altogether, the data presented contribute to elucidate gene signatures and identify differentially expressed genes associated with MDT outcomes in MB patients.

Investigating drug resistance of Mycobacterium leprae in the Comoros: an observational deep-sequencing study.

BACKGROUND: Despite strong leprosy control measures, including effective treatment, leprosy persists in the Comoros. As of May, 2022, no resistance to anti-leprosy drugs had been reported, but there are no nationally representative data. Post-exposure prophylaxis (PEP) with rifampicin is offered to contacts of patients with leprosy. We aimed to conduct a countrywide drug resistance survey and investigate whether PEP led to the emergence of drug resistance in patients with leprosy. METHODS: In this observational, deep-sequencing analysis we assessed Mycobacterium leprae genomes from skin biopsies of patients in Anjouan and Mohéli, Comoros, collected as part of the ComLep (NCT03526718) and PEOPLE (NCT03662022) studies. Skin biopsies that had sufficient M leprae DNA (>2000 bacilli in 2 µl of DNA extract) were assessed for the presence of seven drug resistance-associated genes (ie, rpoB, ctpC, ctpI, folP1, gyrA, gyrB, and nth) using Deeplex Myc-Lep (targeted next generation deep sequencing), with a limit of detection of 10% for minority M leprae bacterial populations bearing a polymorphism in these genes. All newly registered patients with leprosy for whom written informed consent was obtained were eligible for inclusion in the survey. Patients younger than 2 years or with a single lesion on the face did not have biopsies taken. The primary outcome of our study was the proportion of patients with leprosy (ie, new cases, patients with relapses or reinfections, patients who received single (double) dose rifampicin-PEP, or patients who lived in villages where PEP was distributed) who were infected with M leprae with a drug-resistant mutation for rifampicin, fluoroquinolone, or dapsone in the Comoros. FINDINGS: Between July 1, 2017, and Dec 31, 2020, 1199 patients with leprosy were identified on the basis of clinical criteria, of whom 1030 provided a skin biopsy. Of these 1030 patients, 755 (73·3%) tested positive for the M leprae-specific repetitive element-quantitative PCR (qPCR) assay. Of these 755 patients, 260 (34·4%) were eligible to be analysed using Deeplex Myc-Lep. 251 (96·5%) were newly diagnosed with leprosy, whereas nine (3·4%) patients had previously received multidrug therapy. 45 (17·3%) patients resided in villages where PEP had been administered in 2015 or 2019, two (4·4%) of whom received PEP. All seven drug resistance-associated targets were successfully sequenced in 216 samples, 39 samples had incomplete results, and five had no results. No mutations were detected in any of the seven drug resistance-related genes for any patient with successfully sequenced results. INTERPRETATION: This drug resistance survey provides evidence to show that M leprae is fully susceptible to rifampicin, fluoroquinolones, and dapsone in the Comoros. Our results also show, for the first time, the applicability of targeted sequencing directly on skin biopsies from patients with either paucibacillary or multibacillary leprosy. These data suggest that PEP had not selected rifampicin-resistant strains, although further support for this finding should be confirmed with a larger sample size. FUNDING: Effect:Hope, The Mission To End Leprosy, the Fonds Wetenschappelijk Onderzoek, the EU.

Sensitivity of different DNA extraction methods and PCR to detect resistance in patients with leprosy stratified by the bacilloscopic index.

INTRODUCTION: Antimicrobial resistance in leprosy is an emerging problem, and the quantitative impact of low bacilloscopic indexes (BIs) on the sensitivity of molecular tests is unknown. We aimed to evaluate the sensitivity of gene sequencing for the detection of mutations related to antimicrobial resistance in Mycobacterium leprae in patients with low BIs using an analytical model. METHODS: Patients with leprosy were included and divided into two groups depending on their BIs (≥ 2+ and < 2+). The sensitivities of the two DNA extraction methods were compared after amplifying and sequencing the repetitive element (RLEP), folP1, rpoB and gyrA in M. leprae. RESULTS: We included 56 patients with leprosy: 35 had BIs less than 2+ (22 had negative slit-skin smear [SSS] results) and 21 patients had BIs greater than or equal to 2+. The sensitivity of the amplification of the RLEP target and the gene sequencing of folP1, rpoB and gyrA was 50 to 70% lower in patients with a BI less than 2+ and was significantly reduced in patients with lower BIs for all targets (p < 0.001). One patient had a mutation in the folP1 gene, and 14 patients had mutations in the gyrA gene, but no mutations related to antimicrobial resistance were found. CONCLUSIONS: We can conclude that the sensitivity of molecular tests is directly related to the BI, but these tests can still detect up to 20% of the targets in patients with BIs < 2+. New strategies to improve the sensitivity for detecting antimicrobial resistance in leprosy patients and reasonable clinical criteria for follow-up and the introduction of alternative treatments must be developed.

Ofloxacin resistance in multibacillary new leprosy cases from Purulia, West Bengal: a threat to effective secondary line treatment for rifampicin-resistant leprosy cases.

OBJECTIVES: Purulia is one of the high-endemic districts for leprosy in West Bengal (the eastern part of India). The annual new case detection rate (ANCDR) of leprosy in West Bengal is 6.04/100000 (DGHS 2019-20). Our earlier report provided evidence of secondary drug resistance in relapse cases of leprosy. The aim of the current study was to observe primary drug resistance patterns for dapsone, rifampicin, and ofloxacin amongst new leprosy patients from Purulia, West Bengal in order to better understand the emergence of primary resistance to these drugs. METHODS: In the present study, slit-skin smear samples were collected from 145 newly diagnosed leprosy cases from The Leprosy Mission (TLM) Purulia hospital between 2017 and 2018. DNA was extracted from these samples and the Mycobacterium leprae genome was analyzed for genes associated with drug resistance by polymerase chain reaction (PCR), followed by Sanger sequencing. Wild-type strain (Thai-53) and mouse footpad-derived drug-resistant strain (Z-4) were used as reference strains. RESULTS: Of 145 cases, 25 cases showed mutations in genes associated with resistance to rifampicin, dapsone, and ofloxacin (as described by the World Health Organization, rpoB, folP, and gyrA, respectively) through Sanger sequencing. Of these 25 cases, 16 cases showed mutations in ofloxacin, two cases showed mutations in combinations of ofloxacin and rifampicin, four cases showed a mutation only in rifampicin, one case showed mutations in combinations of rifampicin and dapsone, and two cases showed mutations only in dapsone. CONCLUSION: Results from this study indicated the emergence of resistance to antileprosy drugs in new cases of leprosy. As ofloxacin is the alternate drug for the treatment of rifampicin-resistant cases, the emergence of new cases with resistance to ofloxacin indicates that ofloxacin-resistant M. leprae strains are actively circulating in this endemic region (i.e., Purulia, West Bengal), posing challenges for the effective treatment of rifampicin-resistant cases.

Novel therapeutics and drug-delivery approaches in the modulation of glioblastoma stem cell resistance.

Glioblastoma (GBM) is a deadly malignancy with a poor prognosis. An important factor contributing to GBM recurrence is high resistance of GBM cancer stem cells (GSCs). While temozolomide (TMZ), has been shown to consistently extend survival, GSCs grow resistant to TMZ through upregulation of DNA damage repair mechanisms and avoidance of apoptosis. Since a single-drug approach has failed to significantly alter prognosis in the past 15 years, unique approaches such as multidrug combination therapy together with distinctive targeted drug-delivery approaches against cancer stem cells are needed. In this review, a rationale for multidrug therapy using a targeted nanotechnology approach that preferentially target GSCs is proposed with discussion and examples of drugs, nanomedicine delivery systems, and targeting moieties.

Antimicrobial Resistance among Leprosy Patients in Brazil: Real-World Data Based on the National Surveillance Plan.

Brazil ranks second among countries for new cases and first for relapse cases of leprosy worldwide. The Mycobacterium leprae Resistance Surveillance Plan was established. We aimed to present the results of a 2-year follow-up of the National Surveillance Plan in Brazil. A cross-sectional study of leprosy cases was performed to investigate antimicrobial resistance (AMR) in Brazil from October 2018 to September 2020. Molecular screening targeting genes related to dapsone (folP1), rifampin (rpoB), and ofloxacin resistance (gyrA) was performed. During the referral period, 63,520 active leprosy patients were registered in Brazil, and 1,183 fulfilled the inclusion criteria for molecular AMR investigation. In total, only 16 (1.4%) patients had genetic polymorphisms associated with AMR. Of these, 8 (50%) had cases of leprosy relapse, 7 (43.8%) had cases of suspected therapeutic failure with standard treatment, and 1 (6.2%) was a case of new leprosy presentation. M. leprae strains with AMR-associated mutations were found for all three genes screened. Isolates from two patients showed simultaneous resistance to dapsone and rifampin, indicating multidrug resistance (MDR). No significant relationship between clinical variables and the presence of AMR was identified. Our study revealed a low frequency of AMR in Brazil. Isolates were resistant mainly to dapsone, and a very low number of isolates were resistant to rifampin, the main bactericidal agent for leprosy, or presented MDR, reinforcing the importance of the standard World Health Organization multidrug therapy. The greater frequency of AMR among relapsed patients supports the need to constantly monitor this group.

Drug resistance in leprosy: An update following 70years of chemotherapy.

Leprosy is one of the oldest infectious diseases, reported for more than 2000years. Leprosy elimination goal as a public health problem set by the World Health Organization, aiming for a global prevalence rate<1 patient in a population of 10,000, was achieved in 2000 mainly thanks to the worldwide use of leprosy drugs starting in the 1980s and their access at no cost for patients since 1995. However, around 200,000 new cases are still reported each year, particularly in India, Brazil, and Indonesia. As with other bacteria of medical interest, antimicrobial resistance is observed in Mycobacterium leprae strains in several parts of the world, despite multidrug therapy being the recommended standard leprosy treatment to avoid resistance selection since 1982. Therefore, identifying and monitoring resistance is necessary. We provide an overview of the historical facts that led to the current drug resistance situation, the antibiotics effective against M. leprae, their mechanisms of action and resistance, and resistance detection methods. We also discuss therapeutic management of the resistant cases, new genes with potential roles in drug resistance and bacterial adaptation, new drugs under investigation, and the risk for resistance selection with the chemoprophylaxis measures.

Tools to develop antibiotic combinations that target drug tolerance in Mycobacterium tuberculosis.

Combination therapy is necessary to treat tuberculosis to decrease the rate of disease relapse and prevent the acquisition of drug resistance, and shorter regimens are urgently needed. The adaptation of Mycobacterium tuberculosis to various lesion microenvironments in infection induces various states of slow replication and non-replication and subsequent antibiotic tolerance. This non-heritable tolerance to treatment necessitates lengthy combination therapy. Therefore, it is critical to develop combination therapies that specifically target the different types of drug-tolerant cells in infection. As new tools to study drug combinations earlier in the drug development pipeline are being actively developed, we must consider how to best model the drug-tolerant cells to use these tools to design the best antibiotic combinations that target those cells and shorten tuberculosis therapy. In this review, we discuss the factors underlying types of drug tolerance, how combination therapy targets these populations of bacteria, and how drug tolerance is currently modeled for the development of tuberculosis multidrug therapy. We highlight areas for future studies to develop new tools that better model drug tolerance in tuberculosis infection specifically for combination therapy testing to bring the best drug regimens forward to the clinic.