Summary
Colistin is a last‐line antibiotic against Gram‐negative multidrug‐resistant bacteria, but the increased resistance poses a huge challenge to this drug. However, the mechanisms underlying ...such resistance are largely unexplored. The present study first identified the mutations of two genes encoding AceF subunit of pyruvate dehydrogenase (PDH) and TetR family transcriptional regulator in colistin‐resistant Vibrio alginolyticus (VA‐RCT) through genome sequencing. Then, gas chromatography‐mass spectroscopy‐based metabolomics was adopted to investigate metabolic responses since PDH plays a role in central carbon metabolism. Colistin resistance was associated with the reduction of the central carbon metabolism and energy metabolism, featuring the alteration of the pyruvate cycle, a recently characterized energy‐producing cycle. Metabolites in the pyruvate cycle reprogramed colistin‐resistant metabolome to colistin‐sensitive metabolome, resulting in increased gene expression, enzyme activity or protein abundance of the cycle and sodium‐translocating nicotinamide adenine dinucleotide‐ubiquinone oxidoreductase. This reprogramming promoted the production of the proton motive force that enhances the binding between colistin and lipid A in lipopolysaccharide. Moreover, this metabolic approach was effective against VA‐RCT in vitro and in vivo as well as other clinical isolates. These findings reveal a previously unknown mechanism of colistin resistance and develop a metabolome‐reprogramming approach to promote colistin efficiency to combat with colistin‐resistant bacteria.
Summary
Strategy of managing antibiotic‐resistant Vibrio alginolyticus, a bacterial pathogen that threatens human health and animal farming, is not available due to the lack of knowledge about the ...underlying mechanism of antibiotic resistance. Here, we showed that gentamicin‐resistant V. alginolyticus (VA‐RGEN) has four mutations on metabolism and one mutation on a two‐component system by whole‐genome and PCR‐based sequencing, indicating the metabolic shift in VA‐RGEN. Thus, metabolic profile was investigated by GC–MS based metabolomics. Glucose was identified as a crucial biomarker, whose abundance was decreased in VA‐RGEN. Further analysis with iPath, and gene expression and enzyme activity of the pyruvate cycle (the P cycle) demonstrated a global depressed metabolic pathway network in VA‐RGEN. Consistently, NADH, sodium‐pumping NADH:ubiquinone oxidoreductase (Na(+)‐NQR) system, membrane potential and intracellular gentamicin were decreased in VA‐RGEN. These findings indicate that the reduced redox state contributes to antibiotic resistance. Interestingly, exogenous glucose potentiated gentamicin to efficiently kill VA‐RGEN through the promotion of the P cycle, NADH, membrane potential and intracellular gentamicin. The potentiation was further confirmed in a zebrafish model. These results indicate that the gentamicin resistance reduces the P cycle and Na(+)‐NQR system and thereby decreases redox state, membrane potential and gentamicin uptake, which can be reversed by exogenous glucose.
Summary
Antibiotic‐resistant Vibrio alginolyticus poses a big challenge to human health and food safety. It is urgently needed to understand the mechanisms underlying antibiotic resistance to develop ...effective approaches for the control. Here we explored the metabolic difference between gentamicin‐resistant V. alginolyticus (VA‐RGEN) and gentamicin‐sensitive V. alginolyticus (VA‐S), and found that the reactive oxygen species (ROS) generation was altered. Compared with VA‐S, the ROS content in VA‐RGEN was reduced due to the decreased generation and increased breakdown of ROS. The decreased production of ROS was attributed to the decreased central carbon metabolism, which is associated with the resistance to gentamicin. As such a mechanism, we exogenously administrated VA‐RGEN with the glucose that activated the central carbon metabolism and promoted the generation of ROS, but decreased the breakdown of ROS in VA‐RGEN. The gentamicin‐mediated killing was increased with the elevation of the ROS level by a synergistic effect between gentamicin and exogenous glucose. The synergistic effect was inhibited by thiourea, a scavenger of ROS. These results reveal a reduced ROS‐mediated antibiotic resistance mechanism and its reversal by exogenous glucose.
Metabolomics is emerging as a powerful tool for studying metabolic processes, identifying crucial biomarkers responsible for metabolic characteristics and revealing metabolic mechanisms, which ...construct the content of discovery metabolomics. The crucial biomarkers can be used to reprogram a metabolome, leading to an aimed metabolic strategy to cope with alteration of internal and external environments, naming reprogramming metabolomics here. The striking feature on the similarity of the basic metabolic pathways and components among vastly differentspeciesmakesthe reprogrammingmetabolomics possible when the engineered metabolites play biological roles in cellular activity as a substrate of enzymes and a regulator to other molecules including proteins. The reprogramming metabolomics approach can be used to clarify metabolic mechanisms of responding to changed internal and external environmental factors and to establish a framework to develop targeted tools for dealing with the changes such as controlling and/or preventing infection with pathogens and enhancing host immunity against pathogens. This review introduces the current state and trends of discovery metabolomics and reprogramming metabolomics and highlights the importance of reprogramming metabolomics.
•Next-generation antibacterial agents are urgently needed to combat multidrug-resistant, pandrug-resistant gram-negative bacteria and superbugs.•Next generation antibacterial agents are developed by ...promoting the killing efficacy of first- and second-generation antibacterial agents.•Improved influx of antibacterial agents and delayed development of antibacterial resistance are two key features of next-generation antibacterial agents.•We propose the combination of metabolites with first- or/and second-generation antibacterial agents as a strategy for the development of next-generation antibacterial agents.
Existing antibacterial agents can be categorized into two generations, but bacterial insensitivity towards both of these generations poses a serious public health challenge worldwide. Thus, novel approaches and/or novel antibacterials are urgently needed to maintain a concentration of antibacterials that is lethal to bacteria that are resistant to existing antibiotic treatments. Metabolite(s)-based adjuvants that promote antibiotic uptake and enhance antibiotic efficacy are an effective strategy that is unlikely to develop resistance. Thus, we propose a metabolite(s)-based approach, in which metabolites and antibacterials are combined, as a promising strategy for the development of next-generation agents to combat a variety of antibiotic-resistant pathogens.
Multidrug‐resistant bacteria present a major threat to public health that urgently requires new drugs or treatment approaches. Here, we conduct integrated proteomic and metabolomics analyses to ...screen for molecular candidates improving survival of mice infected with Vibrio parahaemolyticus, which indicate that L‐Alanine metabolism and phagocytosis are strongly correlated with mouse survival. We also assess the role of L‐Alanine in improving mouse survival by in vivo bacterial challenge experiments using various bacteria species, including V. parahaemolyticus, Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae. Functional studies demonstrate that exogenous L‐Alanine promotes phagocytosis of these multidrug‐resistant pathogen species. We reveal that the underlying mechanism involves two events boosted by L‐Alanine: TLR4 expression and L‐Alanine‐enhanced TLR4 signaling via increased biosynthesis and secretion of fatty acids, including palmitate. Palmitate enhances binding of lipopolysaccharide to TLR4, thereby promoting TLR4 dimer formation and endocytosis for subsequent activation of the PI3K/Akt and NF‐κB pathways and bacteria phagocytosis. Our data suggest that modulation of the metabolic environment is a plausible approach for combating multidrug‐resistant bacteria infection.
Synopsis
L‐Alanine administration prophylactically and therapeutically protects hosts from infection by multidrug‐resistant bacteria. L‐Alanine enhances the phagocytosis of macrophages by boosting TLR4‐PI3K/AKT‐NFκB signaling and toll‐like receptor 4 expression.
L‐Alanine can be used as prophylactic and therapeutic reagents against infection by multidrug‐resistant bacteria.
L‐Alanine promotes macrophage phagocytosis of multidrug‐resistant bacteria by increasing the production of fatty acids.
Fatty acids enhance LPS‐induced TLR4 dimerization and endocytosis to activate PI3K/AKT and NF‐κB signaling.
L‐Alanine upregulates TLR4 expression in macrophages.
L‐Alanine administration prophylactically and therapeutically protects hosts from infection by multidrug‐resistant bacteria. L‐Alanine enhances the phagocytosis of macrophages by boosting TLR4‐PI3K/AKT‐NFκB signaling and toll‐like receptor 4 expression.
Multidrug-resistant bacteria are an increasingly serious threat to human and animal health. However, novel drugs that can manage infections by multidrug-resistant bacteria have proved elusive. Here ...we show that glucose and alanine abundances are greatly suppressed in kanamycin-resistant Edwardsiella tarda by GC-MS-based metabolomics. Exogenous alanine or glucose restores susceptibility of multidrug-resistant E. tarda to killing by kanamycin, demonstrating an approach to killing multidrug-resistant bacteria. The mechanism underlying this approach is that exogenous glucose or alanine promotes the TCA cycle by substrate activation, which in turn increases production of NADH and proton motive force and stimulates uptake of antibiotic. Similar results are obtained with other Gram-negative bacteria (Vibrio parahaemolyticus, Klebsiella pneumoniae, Pseudomonas aeruginosa) and Gram-positive bacterium (Staphylococcus aureus), and the results are also reproduced in a mouse model for urinary tract infection. This study establishes a functional metabolomics-based strategy to manage infection by antibiotic-resistant bacteria.
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•Glucose and alanine abundances are suppressed in kanamycin-resistant E. tarda•Alanine or glucose, via the TCA cycle, restores bacterial susceptibility to antibiotics•NADH and proton motive force increases, which stimulates uptake of antibiotic•A functional metabolomics-based strategy to kill bacteria is developed
Peng et al. show that exogenous alanine and/or glucose restores susceptibility to antibiotics in antibiotic-resistant bacteria by increasing TCA flux, NADH production, and proton motive force to enhance kanamycin uptake, both in vitro and in a mouse model for urinary tract infection.
This study comprised a review and compilation of literature to gain an in-depth understanding of the impact of rotating shift work on gastrointestinal health. PubMed, CINAHL, and the Cochrane Library ...were searched for studies published between January 1, 1985, and June 30, 2020. Fixed day shifts were defined as work shifts that began between 7:00 and 9:00 in the morning. Shifts beginning at any other time were classified as rotating shifts. A meta-analysis was performed using Comprehensive Meta-Analysis Software (CMA) version 3. In the end, 16 studies were included in the meta-analysis. An odds ratio (OR) of 1.56 (95% confidence interval (CI): 1.24–1.95), indicating that gastrointestinal problems are more common in rotating shift workers than in fixed day shift workers. Four gastrointestinal problems, namely, irritable bowel syndrome, constipation, indigestion, and peptic ulcers, were then analyzed separately. Significant differences between rotating shift workers and fixed day shift workers were found only for indigestion and peptic ulcers. For indigestion, the OR was 1.72 (95% CI: 1.28–2.30). For peptic ulcers, the OR was 1.66 (95% CI: 1.19–2.30). Thus, research indicates that rotating shift work may increase the risk of gastrointestinal problems, particularly indigestion and peptic ulcers.
Serum resistance is a poorly understood but common trait of some difficult-to-treat pathogenic strains of bacteria. Here, we report that glycine, serine and threonine catabolic pathway is ...down-regulated in serum-resistant Escherichia coli, whereas exogenous glycine reverts the serum resistance and effectively potentiates serum to eliminate clinically-relevant bacterial pathogens in vitro and in vivo. We find that exogenous glycine increases the formation of membrane attack complex on bacterial membrane through two previously unrecognized regulations: 1) glycine negatively and positively regulates metabolic flux to purine biosynthesis and Krebs cycle, respectively. 2) α-Ketoglutarate inhibits adenosine triphosphate synthase, which in together promote the formation of cAMP/CRP regulon to increase the expression of complement-binding proteins HtrE, NfrA, and YhcD. The results could lead to effective strategies for managing the infection with serum-resistant bacteria, an especially valuable approach for treating individuals with weak acquired immunity but a normal complement system.
Objectives
This study was to conduct a meta‐analysis of studies that used actigraphs to compare the influence of day and night shifts on the sleep quality of workers as well as examine the moderating ...effect of age.
Methods
Databases including PubMed, CINAHL, the Cochrane Library, MEDLINE, and EBSCOhost were searched for relevant studies published in English between January 1st, 2000 and April 30st, 2021. Our main targets were studies that used actigraphs to assess the sleep quality of night shift workers. This meta‐analysis included 12 papers and was performed using Comprehensive Meta‐Analysis (CMA) Version 3.0. Effect sizes were displayed in a forest plot using standardized mean difference (SMD) and 95% confidence intervals (CI).
Results
Among the sleep quality indices of the day and night shift workers, no significant difference existed in terms of sleep efficiency (SE) (SMD = 0.27, 95% CI: −0.03‐0.57), whereas night shift workers presented longer sleep‐onset latency (SOL) (SMD = 0.62, 95% CI: 0.15‐1.08), greater wake after sleep onset (WASO) (SMD = 0.41, 95% CI: 0.12‐0.70), and longer total sleep time (TST) (SMD = 0.85, 95% CI: 0.32‐1.39) than did day shift workers. The differences between the day and night shift workers in SOL, WASO, and TST did not vary with age.
Conclusions
Among the sleep quality indices, night shift workers presented longer SOL and greater WASO than did day shift workers. However, night shift workers could regulate their rest time and had adequate TST; thus, their SE was not different from that of day shift workers.
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