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Abstract Treatment of Mycobacterium abscessus (Mab) infections is very challenging due to its intrinsic resistance to most available drugs. Therefore, it is crucial to discover novel anti‐Mab drugs. In this study, we explored an intrinsic resistance mechanism through which Mab resists echinomycin (ECH). ECH showed activity against Mab at a minimum inhibitory concentration (MIC) of 2 µg/ml. A ΔembC strain in which the embC gene was knocked out showed hypersensitivity to ECH (MIC: 0.0078–0.0156 µg/ml). The MICs of ECH‐resistant strains screened with reference to ΔembC ranged from 0.25 to 1 µg/ml. Mutations in EmbB, including D306A, D306N, R350G, V555I, and G581S, increased the Mab's resistance to ECH when overexpressed in ΔembC individually (MIC: 0.25–0.5 µg/ml). These EmbB mutants, edited using the CRISPR/Cpf1 system, showed heightened resistance to ECH (MIC: 0.25–0.5 µg/ml). The permeability of these Mab strains with edited genes and overexpression was reduced, as evidenced by an ethidium bromide accumulation assay, but it remained significantly higher than that of the parent Mab. In summary, our study demonstrates that ECH exerts potent anti‐Mab activity and confirms that EmbB and EmbC are implicated in Mab's sensitivity to ECH. Mutation in EmbB may partially compensate for a loss of EmbC function.

The efficacy of many compounds against Mycobacterium tuberculosis is often limited when administered via conventional oral or injection routes due to suboptimal pharmacokinetic characteristics. Inhalation-based delivery methods have been investigated to achieve high local therapeutic doses in the lungs. However, previous models, typically employing wild-type M. tuberculosis strains, were intricate, time-consuming, labor-intensive, and with poor reproducibility. In this study, we developed an autoluminescence-based inhalation administration model to evaluate drug activity by quantifying relative light units (RLUs) emitted from live mice infected with autoluminescent M. tuberculosis. This novel approach offers several advantages: (1) it eliminates the need for anesthesia in mice during administration and simplifies the instrument manipulation; (2) it is cost-effective by utilizing mice instead of larger animals; (3) it shortens the time from several months to 16 or 17 days for obtaining result; (4) it is non-invasive by directly measuring the live RLUs of mice as a surrogate marker for colony-forming units for in vivo drug activity testing; (5) up to six mice can be administrated daily and simultaneously, even 2–3 times/day; (6) results are relatively objective and reproducible results minimizing human factors. Proof-of-concept experiments demonstrated that inhalable rifampicin, isoniazid, and ethambutol showed anti-M. tuberculosis activity at concentrations as low as 0.5, 0.5, and 0.625 mg/mL, respectively, as evidenced by comparing the live RLUs of mice. Furthermore, consistency between RLUs and colony-forming units of the autoluminescent M. tuberculosis in lungs reaffirms the reliability of RLUs as an indicator of drug efficacy, highlighting the potential of this approach for accurately assessing anti-M. tuberculosis activity in vivo. This autoluminescence-based, non-invasive inhalation model offers a substantial reduction in the time, effort, and cost required for evaluating the efficacy of screening new drugs and repurposing old drugs in vivo via inhalation administration.

ABSTRACT The increasing clinical significance of Mycobacterium abscessus is owed to its innate high-level, broad-spectrum resistance to antibiotics and therefore rapidly evolves as an important human pathogen. This warrants the identification of novel targets for aiding the discovery of new drugs or drug combinations to treat M. abscessus infections. This study is inspired by the drug-hypersensitive profile of a mutant M. abscessus (U14) with transposon insertion in MAB_1915. We validated the role of MAB_1915 in intrinsic drug resistance in M. abscessus by constructing a selectable marker-free in-frame deletion in MAB_1915 and complementing the mutant with the same or extended version of the gene and then followed by drug susceptibility testing. Judging by the putative function of MAB_1915, cell envelope permeability was studied by ethidium bromide accumulation assay and susceptibility testing against dyes and detergents. In this study, we established genetic evidence of the role of MAB_1915 in intrinsic resistance to rifampicin, rifabutin, linezolid, clarithromycin, vancomycin, and bedaquiline. Disruption of MAB_1915 has also been observed to cause a significant increase in cell envelope permeability in M. abscessus. Restoration of resistance is observed to depend on at least 27 base pairs upstream of the coding DNA sequence of MAB_1915. MAB_1915 could therefore be associated with cell envelope permeability, and hence its role in intrinsic resistance to multiple drugs in M. abscessus, which presents it as a novel target for future development of effective antimicrobials to overcome intrinsic drug resistance in M. abscessus.IMPORTANCEThis study reports the role of a putative fadD (MAB_1915) in innate resistance to multiple drugs by M. abscessus, hence identifying MAB_1915 as a valuable target and providing a baseline for further mechanistic studies and development of effective antimicrobials to check the high level of intrinsic resistance in this pathogen.

Clofazimine (CFZ) and bedaquiline (BDQ) are currently used for the treatment of multidrug-resistant (MDR) Mycobacterium tuberculosis (Mtb) strains. In recent years, adding CFZ and BDQ to tuberculosis (TB) drug regimens against MDR Mtb strains has significantly improved treatment results, but these improvements are threatened by the emergence of MDR and extensively drug-resistant (XDR) Mtb strains. Recently, CFZ and BDQ have attracted much attention for their strong clinical efficacy, although very little is known about the mechanisms of action, drug susceptibility test (DST), resistance mechanisms, cross-resistance, and pharmacokinetics of these two drugs. In this current review, we provide recent updates on the mechanisms of action, DST, associated mutations with individual resistance and cross-resistance, clinical efficacy, and pharmacokinetics of CFZ and BDQ against Mtb strains. Presently, known mechanisms of resistance for CFZ and/or BDQ include mutations within the Rv0678, pepQ, Rv1979c, and atpE genes. The cross-resistance between CFZ and BDQ may reduce available MDR-/XDR-TB treatment options. The use of CFZ and BDQ for treatment in the setting of limited DST could allow further spread of drug resistance. The DST and resistance knowledge are urgently needed where CFZ and BDQ resistance do emerge. Therefore, an in-depth understanding of clinical efficacy, DST, cross-resistance, and pharmacokinetics for CFZ and BDQ against Mtb can provide new ideas for improving treatment outcomes, reducing mortality, preventing drug resistance, and TB transmission. Along with this, it will also help to develop rapid molecular diagnostic tools as well as novel therapeutic drugs for TB.

ABSTRACT The polymorphism at amino acid 17 of quinolone resistance-determining region of GyrA has been stated with a potential role in fluoroquinolone susceptibility in different mycobacterial species. However, no study has provided dependable evidence so far. Here, we verified that gene-edited Mycobacterium abscessus mutants bearing Ser/Gly at this position were more susceptible to fluoroquinolones than their parent strain and the revertant that supports mycobacteria containing Ser/Gly at this position were more susceptible to fluoroquinolones than those containing Ala. IMPORTANCE Fluoroquinolones (FQs) play a key role in the treatment regimens against tuberculosis and non-tuberculous mycobacterial infections. However, there are significant differences in the sensitivities of different mycobacteria to FQs. In this study, we proved that this is associated with the polymorphism at amino acid 17 of quinolone resistance-determining region of Gyrase A by gene editing. This is the first study using CRISPR-associated recombination for gene editing in Mycobacterium abscessus to underscore the contribution of the amino acid substitutions in GyrA to FQ susceptibilities in mycobacteria.

Photovoltaic (PV) system reliability and durability investigations are essential for industrial maturity and economic success. Recently, PV systems received much interest in Iraq due to many reasons—for instance, power shortage, global warming and pollution. Despite this interest, the precise economic implications of PV system reliability in harsh climates like Iraq remain uncertain. This work assesses the economic implications of PV system component reliability and soiling in Iraq using field experience and historical data. This study identifies the most common failure modes of PV systems installed in Iraq and similar climatic regions, and also ranks their severity. Simulations explore scenarios of PV module degradation rates, inverter lifetimes, soiling rates, and cleaning intervals, revealing that soiling has the most detrimental effect, with cleaning frequency leading to Levelized Cost of Electricity (LCOE) losses of over 30%, depending on the location. Inverter lifetime contributes to LCOE losses between 4 and 6%, depending on the PV system’s location. This study also evaluates the impact of tilt angle as a mitigation strategy for reducing soiling loss and its economic implications, finding that installing PV modules at higher tilt angles could reduce the economic impact of soiling by approximately 4.4%. Additionally, the optimal cleaning strategy identified is fully automated dry cleaning with robots, outperforming other strategies economically. Overall, the findings highlight that the LCOE in Iraq is relatively high compared to the global weighted average for utility-scale PV systems, primarily due to high soiling and degradation rates. The LCOE varies within the country, influenced by different degradation rates. This study aims to assist PV stakeholders in Iraq and the Middle East and North Africa (MENA) region in accurately estimating solar bankability; moreover, increasing reliability by minimizing the technical and financial risks by considering key parameters specific to these regions.

IntroductionInfections caused by non-tuberculosis mycobacteria are significantly worsening across the globe. M. fortuitum complex is a rapidly growing pathogenic species that is of clinical relevance to both humans and animals. This pathogen has the potential to create adverse effects on human healthcare.MethodsThe MF GZ001 clinical strain was collected from the sputum of a 45-year-old male patient with a pulmonary infection. The morphological studies, comparative genomic analysis, and drug resistance profiles along with variants detection were performed in this study. In addition, comparative analysis of virulence genes led us to understand the pathogenicity of this organism.ResultsBacterial growth kinetics and morphology confirmed that MF GZ001 is a rapidly growing species with a rough morphotype. The MF GZ001 contains 6413573 bp genome size with 66.18 % high G+C content. MF GZ001 possesses a larger genome than other related mycobacteria and included 6156 protein-coding genes. Molecular phylogenetic tree, collinearity, and comparative genomic analysis suggested that MF GZ001 is a novel member of the M. fortuitum complex. We carried out the drug resistance profile analysis and found single nucleotide polymorphism (SNP) mutations in key drug resistance genes such as rpoB, katG, AAC(2')-Ib, gyrA, gyrB, embB, pncA, blaF, thyA, embC, embR, and iniA. In addition, the MF GZ001strain contains mutations in iniA, iniC, pncA, and ribD which conferred resistance to isoniazid, ethambutol, pyrazinamide, and para-aminosalicylic acid respectively, which are not frequently observed in rapidly growing mycobacteria. A wide variety of predicted putative potential virulence genes were found in MF GZ001, most of which are shared with well-recognized mycobacterial species with high pathogenic profiles such as M. tuberculosis and M. abscessus.DiscussionOur identified novel features of a pathogenic member of the M. fortuitum complex will provide the foundation for further investigation of mycobacterial pathogenicity and effective treatment.

Tuberculosis (TB), an infectious disease, has been a leading cause of morbidity and mortality for decades. The causative agent of TB is the Mycobacterium tuberculosis (Mtb) which can infects various parts of the body, mainly the lungs in pulmonary TB cases. Mycobacterium bovis Bacillus Calmette–Guerin (BCG) is the only approved vaccine for TB, but its efficiency to combat pulmonary TB is limited. Multidrug-resistant (MDR) TB and extensive drug-resistant (XDR) TB requires the evolution of more potent vaccines. Therefore, this research aims to generate a universal TB subunit vaccine using advanced immunoinformatics techniques. In generating a novel multiepitope subunit vaccine, we selected the conserved and experimentally confirmed antigens Rv0058, Rv0101, and Rv3343. After a rigorous evaluation, the top candidates from predicted Helper T-lymphocytes (HTL), Cytotoxic T-lymphocytes (CTL), and B-cell epitopes were considered potential vaccine candidates. Immunogenicity was enhanced by the addition of an adjuvant to the ultimate construct of the vaccine. B-cell epitopes predictions guaranteed the eventual induction of a humoral response. Thereafter, dynamics simulations and molecular docking validated the vaccine-receptor complex’s stability and high affinity for the immune receptor TLR-3. Also, immune simulations revealed the significantly elevated levels of immunoglobulins such as IgM, cytokines such as interleukin-2, helper T (Th) cells, and cytotoxic T-cell populations. These results agreed with the actual inflammatory response and showed rapid antigen clearance after manifold exposure. Finally, the E. coli K12 strain was confirmed via in-silico cloning for quality expression. Nevertheless, in vivo experiments should be performed to validate the safety of the proposed vaccine and its inherent ability to prevent TB infection.