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1. ANTIMICROBIAL WOUND DRESSINGS FOR FULL-THICKNESS INFECTED BURN WOUNDS

   https://doi.org/10.1097/SHK.0000000000002426  

   Dhyani, Abhishek; Repetto, Taylor; VanAken, Shannon; Nemzek, Jean; VanEpps, J Scott; Mehta, Geeta; Tuteja, Anish (January 2024, Shock)

   Remick, Daniel (Ed.)

   ABSTRACT Infection of wounds delays healing, increases treatment costs, and leads to major complications. Current methods to manage such infections include antibiotic ointments and antimicrobial wound dressings, both of which have significant drawbacks, including frequent reapplication and contribution to antimicrobial resistance. In this work, we developed wound dressings fabricated with a medical-grade polyurethane coating composed of natural plant secondary metabolites, cinnamaldehyde, and alpha-terpineol. Our wound dressings are easy to change and do not adhere to the wound bed. They kill gram-positive and -negative microbes in infected wounds due to the Food and Drug Administration–approved for human consumption components. The wound dressings were fabricated by dip coating. Antimicrobial efficacy was determined by quantifying the bacteria colonies after a 24 h of immersion. Wound healing and bacterial reduction were assessed in anin vivofull-thickness porcine burn model. Our antimicrobial wound dressings showed a > 5-log reduction (99.999%) of different gram-positive and gram-negative bacteria, while maintaining absorbency. In thein vivoporcine burn model, our wound dressings were superior to bacitracin in decreasing bacterial burden during daily changes, without interfering with wound healing. Additionally, the dressings had a significantly lower adhesion to the wound bed. Our antimicrobial wound dressings reduced the burden of clinically relevant bacteria more than commercial antimicrobial wound dressings. In anin vivoinfected burn wound model, our coatings performed as well or better than bacitracin. We anticipate that our wound dressings would be useful for the treatment of various types of acute and chronic wounds. 

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2. Trapping of Antibacterial Agents within Hydrophobic Films of Polyphosphazene Polyelectrolytes

   Albright, V.; Hlushko, H.; Co, C.; Armbrister, Sh.; Hernandez, S.; Andreo, M.; Jayaraman, A.; Marin, A.; Andrianov, A.; Sukhishvili, S. (August 2018, Abstracts of papers - American Chemical Society)

   Direct layer-by-layer (LbL) assembly of cationic, small-molecule antibacterial bioactives with water-soluble, ionic polyphosphazenes (PPzs) containing trifluoroethoxy and carboxy substitients is reported. First, influence of PPzs hydrophobicity and antibiotic charge density on LbL assembly was studied via evolution of dry film thickness. We found that the use of fluorinated PPz polyelectrolytes enhanced ionic pairing within LbL coatings, and that increasing charge density of small molecules increased antibiotic uptake. This strategy was successful even in the case of gentamicin, a hydrophilic, small antibiotic with only 3 to 4 positive charges at pH 7.5. Confirmation of antibiotic presence in films was demonstrated via x-ray photoelectron spectroscopy. Importantly, LbL films of fluorinated PPz polyelectrolytes retained antibiotics in physiological conditions due to the enhanced hydrophobic interactions. In contrast, LbL films of non-fluorinated PPzs released antibiotics at low pH and in the presence of salt following the charge renormalization argument. The potential of these coatings with a biomedically relevant bacterial strain, Staphylococcus aureus, is discussed. 

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3. Soil type and moisture content alter soil microbial responses to manure from cattle administered antibiotics

   https://doi.org/10.1007/s11356-024-32903-z  

   Shawver, Sarah; Ishii, Satoshi; Strickland, Michael S.; Badgley, Brian (March 2024, Environmental Science and Pollution Research)

   Abstract Growing concerns about the global antimicrobial resistance crisis require a better understanding of how antibiotic resistance persists in soil and how antibiotic exposure impacts soil microbial communities. In agroecosystems, these responses are complex because environmental factors may influence how soil microbial communities respond to manure and antibiotic exposure. The study aimed to determine how soil type and moisture alter responses of microbial communities to additions of manure from cattle treated with antibiotics. Soil microcosms were constructed using two soil types at 15, 30, or 45% moisture. Microcosms received biweekly additions of manure from cattle given cephapirin or pirlimycin, antibiotic-free manure, or no manure. While soil type and moisture had the largest effects on microbiome structure, impacts of manure treatments on community structure and individual ARG abundances were observed across varying soil conditions. Activity was also affected, as respiration increased in the cephapirin treatment but decreased with pirlimycin. Manure from cattle antibiotics also increased NH₄⁺and decreased NO₃⁻availability in some scenarios, but the effects were heavily influenced by soil type and moisture. Overall, this work demonstrates that environmental conditions can alter how manure from cattle administered antibiotics impact the soil microbiome. A nuanced approach that considers environmental variability may benefit the long-term management of antibiotic resistance in soil systems. 

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4. PAPER-BASED WEARABLE MOIST-ELECTRIC GENERATORS WITH EFFICIENT ATMOSPHERIC WATER CAPTURE

   Gao, Yang; Elhadad, Anwar; Choi, Seokheun (June 2024, Technical digest SolidState Sensor Actuator and Microsystems Workshop)

   This study unveils a pioneering yet straightforward approach to creating a moist-electric generator, using paper as the primary substrate and integrating bacterial endospores within it. The distribution of these endospores is meticulously regulated by the paper's inherent capillary action. The functional groups present on the endospores enhance moisture absorption and facilitate ion dissociation, resulting in a pronounced potential gradient driven by the variation in water content and endospore concentration. To augment water capture efficiency, a paper-based Janus layer combining hydrophobic and hydrophilic properties is applied atop the paper-based moist-electric generator. This dual-sided membrane excels in moisture condensation from the atmosphere and ensures unidirectional water transport to the generator, thus ensuring substantial electrical output even under low relative humidity conditions. This research not only addresses the challenges of power generation in wearable paper-based devices but also heralds new pathways for the development of autonomous, cost-effective, and eco-friendly energy solutions for wearable technologies. 

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5. Sub-inhibitory antibiotic treatment selects for enhanced metabolic efficiency

   https://doi.org/10.1128/spectrum.03241-23  

   Aduru, Sai Varun; Szenkiel, Karolina; Rahman, Anika; Ahmad, Mehrose; Fabozzi, Maya; Smith, Robert P.; Lopatkin, Allison J. (February 2024, Microbiology Spectrum)

   Zhang, Xue (Ed.)

   ABSTRACT Bacterial growth and metabolic rates are often closely related. However, under antibiotic selection, a paradox in this relationship arises: antibiotic efficacy decreases when bacteria are metabolically dormant, yet antibiotics select for resistant cells that grow fastest during treatment. That is, antibiotic selection counterintuitively favors bacteria with fast growth but slow metabolism. Despite this apparent contradiction, antibiotic resistant cells have historically been characterized primarily in the context of growth, whereas the extent of analogous changes in metabolism is comparatively unknown. Here, we observed that previously evolved antibiotic-resistant strains exhibited a unique relationship between growth and metabolism whereby nutrient utilization became more efficient, regardless of the growth rate. To better understand this unexpected phenomenon, we used a simplified model to simulate bacterial populations adapting to sub-inhibitory antibiotic selection through successive bottlenecking events. Simulations predicted that sub-inhibitory bactericidal antibiotic concentrations could select for enhanced metabolic efficiency, defined based on nutrient utilization: drug-adapted cells are able to achieve the same biomass while utilizing less substrate, even in the absence of treatment. Moreover, simulations predicted that restoring metabolic efficiency would re-sensitize resistant bacteria exhibiting metabolic-dependent resistance; we confirmed this result using adaptive laboratory evolutions ofEscherichia coliunder carbenicillin treatment. Overall, these results indicate that metabolic efficiency is under direct selective pressure during antibiotic treatment and that differences in evolutionary context may determine both the efficacy of different antibiotics and corresponding re-sensitization approaches. IMPORTANCEThe sustained emergence of antibiotic-resistant pathogens combined with the stalled drug discovery pipelines highlights the critical need to better understand the underlying evolution mechanisms of antibiotic resistance. To this end, bacterial growth and metabolic rates are often closely related, and resistant cells have historically been characterized exclusively in the context of growth. However, under antibiotic selection, antibiotics counterintuitively favor cells with fast growth, and slow metabolism. Through an integrated approach of mathematical modeling and experiments, this study thereby addresses the significant knowledge gap of whether antibiotic selection drives changes in metabolism that complement, and/or act independently, of antibiotic resistance phenotypes. 

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