Evaluating the potential for resistance development in Gram-negative bacteria to antimicrobial blue light (at 405 nm): in vitro and in vivo studies

ABSTRACT DW-224a showed the most potent in vitro activity among the quinolone compounds tested against clinical isolates of gram-positive bacteria. Against gram-negative bacteria, DW-224a was slightly less active than the other fluoroquinolones. The in vivo activities of DW-224a against gram-positive bacteria were more potent than those of other quinolones.

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Structural insights into a novel family of integral membrane siderophore reductases

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2101952118 ◽

2021 ◽

Vol 118 (34) ◽

pp. e2101952118

Author(s):

Inokentijs Josts ◽

Katharina Veith ◽

Vincent Normant ◽

Isabelle J. Schalk ◽

Henning Tidow

Keyword(s):

Iron Uptake ◽

Bacterial Species ◽

Gram Negative Bacteria ◽

Inner Membrane ◽

Gram Negative ◽

Inner Membrane Protein ◽

Uptake Studies ◽

Structural Insights

Gram-negative bacteria take up the essential ion Fe3+ as ferric-siderophore complexes through their outer membrane using TonB-dependent transporters. However, the subsequent route through the inner membrane differs across many bacterial species and siderophore chemistries and is not understood in detail. Here, we report the crystal structure of the inner membrane protein FoxB (from Pseudomonas aeruginosa) that is involved in Fe-siderophore uptake. The structure revealed a fold with two tightly bound heme molecules. In combination with in vitro reduction assays and in vivo iron uptake studies, these results establish FoxB as an inner membrane reductase involved in the release of iron from ferrioxamine during Fe-siderophore uptake.

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Synergy and remarkable specificity of antimicrobial peptides in vivo using a systematic knockout approach

eLife ◽

10.7554/elife.44341 ◽

2019 ◽

Vol 8 ◽

Cited By ~ 29

Author(s):

Mark Austin Hanson ◽

Anna Dostálová ◽

Camilla Ceroni ◽

Mickael Poidevin ◽

Shu Kondo ◽

...

Keyword(s):

Antimicrobial Peptides ◽

Fungal Pathogens ◽

Gene Editing ◽

Cationic Peptides ◽

Gram Negative Bacteria ◽

Biological Processes ◽

Gram Negative ◽

Bacteria And Fungi

Antimicrobial peptides (AMPs) are host-encoded antibiotics that combat invading microorganisms. These short, cationic peptides have been implicated in many biological processes, primarily involving innate immunity. In vitro studies have shown AMPs kill bacteria and fungi at physiological concentrations, but little validation has been done in vivo. We utilized CRISPR gene editing to delete most known immune-inducible AMPs of Drosophila, namely: 4 Attacins, 2 Diptericins, Drosocin, Drosomycin, Metchnikowin and Defensin. Using individual and multiple knockouts, including flies lacking these ten AMP genes, we characterize the in vivo function of individual and groups of AMPs against diverse bacterial and fungal pathogens. We found that Drosophila AMPs act primarily against Gram-negative bacteria and fungi, contributing either additively or synergistically. We also describe remarkable specificity wherein certain AMPs contribute the bulk of microbicidal activity against specific pathogens, providing functional demonstrations of highly specific AMP-pathogen interactions in an in vivo setting.

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Visualizing the Potential Impairment of Polymyxin B to Central Nervous System Through MR Susceptibility-Weighted Imaging

Frontiers in Pharmacology ◽

10.3389/fphar.2021.784864 ◽

2021 ◽

Vol 12 ◽

Author(s):

Ni Zhang ◽

Lichong Zhu ◽

Qiuhong Ouyang ◽

Saisai Yue ◽

Yichun Huang ◽

...

Keyword(s):

Central Nervous System ◽

Nervous System ◽

Polymyxin B ◽

Susceptibility Weighted Imaging ◽

Gram Negative Bacteria ◽

Severe Toxicity ◽

Gram Negative ◽

The Impact

Polymyxin B (PMB) exert bactericidal effects on the cell wall of Gram-negative bacteria, leading to changes in the permeability of the cytoplasmic membrane and resulting in cell death, which is sensitive to the multi-resistant Gram-negative bacteria. However, the severe toxicity and adverse side effects largely hamper the clinical application of PMB. Although the molecular pathology of PMB neurotoxicity has been adequately studied at the cellular and molecular level. However, the impact of PMB on the physiological states of central nervous system in vivo may be quite different from that in vitro, which need to be further studied. Therefore, in the current study, the biocompatible ultra-uniform Fe3O4 nanoparticles were employed for noninvasively in vivo visualizing the potential impairment of PMB to the central nervous system. Systematic studies clearly reveal that the prepared Fe3O4 nanoparticles can serve as an appropriate magnetic resonance contrast agent with high transverse relaxivity and outstanding biosafety, which thus enables the following in vivo susceptibility-weighted imaging (SWI) studies on the PMB-treated mice models. As a result, it is first found that the blood-brain barrier (BBB) of mice may be impaired by successive PMB administration, displaying by the discrete punctate SWI signals distributed asymmetrically across brain regions in brain parenchyma. This result may pave a noninvasive approach for in-depth studies of PMB medication strategy, monitoring the BBB changes during PMB treatment, and even assessing the risk after PMB successive medication in multidrug-resistant Gram-negative bacterial infected patients from the perspective of medical imaging.

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Synergistic effect of antimicrobial blue light (at 405 nm) and quinine against multidrug-resistant infections: in vitro and in vivo studies

Photonic Diagnosis and Treatment of Infections and Inflammatory Diseases II ◽

10.1117/12.2506033 ◽

2019 ◽

Author(s):

Leon G. Leanse ◽

Pu-Ting Dong ◽

Sharon X. Goh ◽

Ying Wang ◽

Min Lu ◽

...

Keyword(s):

Synergistic Effect ◽

Blue Light ◽

Multidrug Resistant ◽

In Vivo Studies

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Elimination of Extracellular Adenosine Triphosphate for the Rapid Prediction of Quantitative Plate Counts in 24 h Time-Kill Studies against Carbapenem-Resistant Gram-Negative Bacteria

Microorganisms ◽

10.3390/microorganisms8101489 ◽

2020 ◽

Vol 8 (10) ◽

pp. 1489

Author(s):

Yiying Cai ◽

Jonathan J. Ng ◽

Hui Leck ◽

Jocelyn Q. Teo ◽

Jia-Xuan Goh ◽

...

Keyword(s):

Gram Negative Bacteria ◽

Gram Negative ◽

Carbapenem Resistant ◽

Infection Models ◽

Rapid Prediction ◽

Atp Bioluminescence ◽

Plate Counts ◽

Time Kill

Traditional in vitro time-kill studies (TKSs) require viable plating, which is tedious and time-consuming. We used ATP bioluminescence, with the removal of extracellular ATP (EC-ATP), as a surrogate for viable plating in TKSs against carbapenem-resistant Gram-negative bacteria (CR-GNB). Twenty-four-hour TKSs were conducted using eight clinical CR-GNB (two Escherichia coli, two Klebsiella spp., two Acinetobacter baumannii, two Pseudomonas aeruginosa) with multiple single and two-antibiotic combinations. ATP bioluminescence and viable counts were determined at each timepoint (0, 2, 4, 8, 24 h), with and without apyrase treatment. Correlation between ATP bioluminescence and viable counts was determined for apyrase-treated and non-apyrase-treated samples. Receiver operator characteristic curves were plotted to determine the optimal luminescence threshold to discriminate between inhibitory/non-inhibitory and bactericidal/non-bactericidal combinations, compared to viable counts. After treatment of bacteria with 2 U/mL apyrase for 15 min at 37 °C, correlation to viable counts was significantly higher compared to untreated samples (p < 0.01). Predictive accuracies of ATP bioluminescence were also significantly higher for apyrase-treated samples in distinguishing inhibitory (p < 0.01) and bactericidal (p = 0.03) combinations against CR-GNB compared to untreated samples, when all species were collectively analyzed. We found that ATP bioluminescence can potentially replace viable plating in TKS. Our assay also has applications in in vitro and in vivo infection models.

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