Bedquiline Resistance Mutations: Correlations with Drug Exposures and Impact on the Proteome in M. tuberculosis.

Bedaquiline (BDQ) is an effective drug for the treatment of drug-resistant tuberculosis. Mutations in atpE, which encodes the target of BDQ, are associated with large increases in MICs. Mutations in Rv0678 that derepress the transcription of the MmpL5-MmpS5 efflux transporter are associated with smaller increases in MICs. However, Rv0678 mutations are the most common mutations that are associated with BDQ resistance in clinical isolates, and they also confer cross-resistance to clofazimine (CFZ). To investigate the mechanism of BDQ resistance and the correlation between Rv0678 mutations and target-based atpE mutations, M. tuberculosis strains were exposed to different concentrations of BDQ or CFZ to select Rv0678 mutations and atpE mutations. Gene overexpression strains were constructed to illustrate the roles of MmpL5 and MmpS5. A quantitative proteome analysis was performed to compare the BDQ-resistant mutants to the isogenic strain H37Rv. Here, we report that the Rv0678 mutations were more readily selected than were the atpE mutations at low concentrations of BDQ or CFZ. The atpE mutations were selected by high concentrations of BDQ exposure. The overexpression of both mmpL5 and mmpS5 reduced the susceptibility of Mycobacterium tuberculosis to BDQ and CFZ. Secreted immunogenic proteins and proteins involved in the biosynthesis and transport of phthiocerol dimycocerosates were associated with Rv0678 mutations conferring BDQ resistance in the proteome analysis. In conclusion, exposure to different bedaquiline concentrations resulted in the selection of different mutations. The coexpression of MmpL5 and MmpS5 contributed to drug resistance and upregulated pathogenic proteins in M. tuberculosis, suggesting MmpL5-MmpS5 as a new potential target for antituberculosis drug development. These results warrant further surveillance for the evolution of BDQ resistance during clinical usage.

The influence of the doping concentration and reverse intersystem crossing on the efficiency of tricomponent organic light-emitting diodes with the thermally activated delayed fluorescence exciplex emitter.

In this work, we fabricate a series of full-fluorescent organic light-emitting diodes (OLEDs) with the thermally activated delayed fluorescence (TADF) exciplex emitter in order to improve the efficiency through the reverse intersystem crossing (RISC) process. The TADF exciplex emitters are made up of a mixture of P-type materials (DMAC-DPS and mCBP) and n-type material (PO-T2T), among which DMAC-DPS also classes as a TADF material. The change in doping concentration will affect the intermolecular distance and the composition of TADF material and two kinds of exciplexes (DMAC-DPS:PO-T2T and mCBP:PO-T2T) in the luminescent layer (EML). Different materials and concentrations of doping not only add new RISC channels but also alter the original RISC channels, thereby affecting the performance of devices. It is beneficial for improving efficiency by increasing the proportion of independent TADF material and reducing the proportion of exciplex (DMAC-DPS:PO-T2T) in the EML, which can be controlled by doping. When the ratio of DMAC-DPS, PO-T2T and mCBP in the EML is 1 : 1 : 2, we achieve the optimal electro-optic performance in device A3, with maximum current efficiency, power efficiency, and luminance of 41.64 cd A-1, 43.42 lm W-1, and 23 080 cd m-2, respectively.

New generation fluoroquinolone sitafloxacin could potentially overcome the majority levofloxacin and moxifloxacin resistance in multidrug-resistant Mycobacterium tuberculosis.

Introduction. Pre-existing fluoroquinolones (FQs) resistance is a major threat in treating multidrug-resistant (MDR) tuberculosis. Sitafloxacin (Sfx) is a new broad-spectrum FQ.Hypothesis. Sfx is more active against drug-resistant Mycobacterium tuberculosis (Mtb) isolates.Aim. To determine whether there is cross-resistance between Sfx and ofloxacin (Ofx), levofloxacin (Lfx) and moxifloxacin (Mfx) in MDR Mtb.Methods. A total of 106 clinical Mtb isolates, including 23 pan-susceptible and 83 MDR strains, were analysed for Sfx, Lfx and Mfx resistance using MIC assay. The isolates were also subjected to whole-genome sequencing to analyse drug-resistant genes.Results. Sfx exhibited the most robust inhibition activity against Mtb clinical isolates, with a MIC50 of 0.0313 µg ml-1 and MIC90 of 0.125 µg ml-1, which was lower than that of Mfx (MIC50 = 0.0625 µg ml-1, MIC90 = 1 µg ml-1) and Lfx (MIC50 = 0.125 µg ml-1, MIC90 = 2 µg ml-1). We determined the tentative epidemiological cut-off values as 0.5 µg ml-1 for Sfx. Also, 8.43% (7/83), 43.37% (36/83), 42.17% (35/83) and 51.81% (43/83) MDR strains were resistant to Sfx, Mfx, Lfx and Ofx, respectively. Cross-resistance between Ofx, Lfx and Mfx was 80.43% (37/46). Only 15.22% (7/46) of the pre-existing FQs resistance isolates were resistant to Sfx. Among the 30 isolates with mutations in gyrA or gyrB, 5 (16.67%) were Sfx resistant. The combination of Sfx and rifampicin could exert partial synergistic effects, and no antagonism between Sfx and six clinically important anti-Mtb antibiotics was evident.Conclusion. Sfx exhibited superior activity against MDR isolates comparing to Lfx and Mfx, and could potentially overcome the majority pre-existing FQs resistance in Mtb strains.

Bibliometric analysis of tuberculosis molecular epidemiology based on CiteSpace.

Background: Tuberculosis is a communicable disease that is a major cause of ill health. Bibliometrics is an important statistical methodology used to analyze articles and other publications in the literature study. In this study, publications on molecular epidemiology were analyzed using bibliometric analysis. The statistical analysis of influential publications, journals, countries and authors was first conducted. Methods: The Web of Science database was searched for publications on the molecular epidemiology of tuberculosis with the keywords "tuberculosis" and "molecular epidemiology" in the title. The number of publications, citation analysis, co-authorship of the author, institution and country, keyword co-occurrence, and reference co-citations were analyzed. Results: A total of 225 journal articles were retrieved. The mean citation was 37.72 per article and 292.69 per year. The annual publications on molecular epidemiology fluctuated within a certain range in the past. Journal of Clinical Microbiology is the most published journal with 33 articles. RASTOGI N is the most prolific author with 11 articles. The top 1 research institution is Inst Pasteur Guadeloupe. Stratified by the number of publications, the USA was the most prolific country. It also cooperates closely with other countries. Burstness analysis of references and keywords showed that the developing research trends in this field mainly focused on "genetic diversity" and "lineage" during the past decade. Conclusion: The annual publications on tuberculosis molecular epidemiology fluctuated within a specific range in the past decade. The USA continues to dominate research output and funding. The exchange of expertise, ideas, and technology is of paramount importance in this field. More frequent and deeper cooperation among countries or institutions will be essential in the future.

Interactions of linezolid and second-line anti-tuberculosis agents against multidrug-resistant Mycobacterium tuberculosis in vitro and in vivo.

OBJECTIVES: The objectives of this study were to evaluate the interactions between linezolid (LZD) and second-line anti-tuberculosis (TB) agents in susceptible and multidrug-resistant (MDR) TB in vitro, and to validate the in vitro results in a murine TB model. METHODS: The minimum inhibitory concentrations of LZD and seven second-line anti-TB drugs against H37Rv and three multidrug-resistant clinical isolates were determined by Alamar Blue assay, and the interaction patterns of LZD and the seven second-line anti-TB agents against the four isolates were studied using a dynamic checkerboard method. The activities of these combinations against Mycobacterium tuberculosis were evaluated in a murine model of TB. RESULTS: The combination of LZD + capreomycin exhibited partial synergism for three of four isolates, LZD + para-aminosalicylic acid exhibited partial synergism for two of four isolates, and LZD + levofloxacin and LZD + amikacin exhibited partial synergism for one of four isolates; all other combinations showed indifference or an additive effect in vitro. The activities of six combinations and the standard regimen rifampicin + isoniazid + pyrazinamide were investigated in a murine model of TB (infection with H37Rv). Significant reductions in colony-forming units (CFU) were found in LZD + capreomycin and LZD + clofazimine groups when the CFU in the lungs on day 0 (the day of beginning treatment) was compared with the CFU in the lungs after 2 months of treatment. CONCLUSIONS: These combinations of LZD and second-line anti-TB drugs were all active against MDR-TB with indifference or an additive effect, except LZD + capreomycin, which showed partial synergy.

Activity of linezolid-containing regimens against multidrug-resistant tuberculosis in mice.

The objective of the present study was to compare the activities of regimens containing linezolid (LZD) with those not containing LZD against Mycobacterium tuberculosis infection in mice. The three regimens excluding LZD selected in this study are often used in practice against multidrug-resistant tuberculosis (MDR-TB). When LZD was added to these MDR-TB regimens, the combinations were significantly more active after 2 months of therapy with regard to lung CFU reductions. The activity of LZD-containing regimens was greater than the World Health Organization's standard first-line regimen of rifampicin+isoniazid+pyrazinamide. In particular, when LZD was included in the combination levofloxacin+amikacin+para-aminosalicylic acid+pyrazinamide+clofazimine, culture negativity of the lungs was reached after 2 months of treatment in every case. In addition, the serum levels of interleukin-10 and interferon-γ of mice were determined and were found not to be surrogate markers of bacterial clearance.