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Background Cefiderocol (CFDC) is a siderophore-conjugated cephalosporin with broad activity against Gram-negative (GN) bacteria, including multidrug-resistant organisms. GN bacteria such as Enterobacterales (ENT), Pseudomonas aeruginosa (PsA), Acinetobacter baumannii complex (ABC), and Stenotrophomonas maltophilia (StM) can be challenging to treat and are often carbapenem-resistant (CR). Regional susceptibility of CFDC and comparators were investigated against US GN isolates collected in 2020-2021 as part of the SENTRY Antimicrobial Surveillance Program. Methods GN pathogens were consecutively collected from 32 US hospitals between 2020 to 2021. Susceptibility testing was performed using the broth microdilution method. CFDC was tested in iron-depleted cation-adjusted Mueller-Hinton broth. FDA or CLSI breakpoints were used where available. Other agents tested included the beta-lactam/beta-lactamase inhibitor (BL/BLI) combinations ceftazidime-avibactam, ceftolozane-tazobactam, imipenem-relebactam, meropenem-vaborbactam, piperacillin-tazobactam, and ampicillin-sulbactam. CR-PsA, or CRAB was defined as meropenem resistant while CRE was defined as imipenem or meropenem resistant by CLSI breakpoints. Results A total of 8328 ENT, 2241 PsA, 586 ABC, and 404 StM were collected. For ENT and PsA, CFDC susceptibility between the 9 US Census regions remained above 98% susceptible by CLSI or FDA breakpoints in all regions (Table 1). Amongst the BL/BLI combinations, the majority had >90% susceptibility across regions except for piperacillin-tazobactam with 79.7% for ENT and 65.9% for PsA in the MidAtlantic by FDA breakpoints. For ABC and StM, CFDC susceptibility was > 88% across all regions. For CR pathogens, 96 CRE, 327 CR-PsA, and 199 CRAB were collected. CFDC had >87.5% susceptibility in all regions for CRE and CR-PSA. For CRAB, 4 regions were > 87.5% by FDA breakpoints and the lowest was 63.6% in 11 isolates in the Mountain region (Table 2). For CRAB, every BL/BLI had susceptibility ≤27.3% in every region. Ampicillin-sulbactam had 27.3% susceptibility in the Mountain region. Table 1 Susceptibility of Cefiderocol against Enterobacterales, Pseudomonas aeruginosa, Acinetobacter baumannii complex and Stenotrophomonas maltiphilia isolates in the cefiderocol program collected from medical centers in the USA Table 2: Susceptibility of cefiderocol against CRE, CR Pseudomonas aeruginosa, and CR Acinetobacter baumannii complex isolates in the cefiderocol program collected from medical centers in the USA Conclusion US GN isolates, including CR pathogens, had high susceptibilities to CFDC across the US census regions. CFDC remains an important treatment option for GN infections in all US census regions. Disclosures Frank H. Kung, PhD, Shionogi Inc: Employee Sean Nguyen, n/a, Shionogi: Employee Christine M. Slover, PharmD, Shionogi: Employee Dee Shortridge, PhD, AbbVie: Grant/Research Support|JMI Laboratory: Employee|Melinta: Grant/Research Support|Menarini: Grant/Research Support|Shionogi: Grant/Research Support Jennifer M. Streit, BS, MT(ASCP), Cidara: Grant/Research Support|GSK: Grant/Research Support|Melinta: Grant/Research Support|Shionogi: Grant/Research Support Roger Echols, MD, Shionogi: Advisor/Consultant Roger Echols, MD, Shionogi: Advisor/Consultant Roger Echols, MD, Shionogi: Advisor/Consultant Miki Takemura, n/a, Shionogi: Employee Yoshinori Yamano, PhD, Shionogi: Employee.

The construction of biomaterials with which to limit the growth of cells or to limit the adsorption of proteins is essential for understanding biological phenomena. Here, we describe a novel method to simply and easily create thin layers of poly (2-hydroxyethyl methacrylate) (p-HEMA) for protein and cellular patterning via etching with ethanol and microfluidic devices. First, a cell culture surface or glass coverslip is coated with p-HEMA. Next, a polydimethylsiloxane (PDMS) microfluidic is placed onto the p-HEMA surface, and ethanol is aspirated through the device. The PDMS device is removed, and the p-HEMA surface is ready for protein adsorption or cell plating. This method allows for the fabrication of 0.3 µm thin layers of p-HEMA, which can be etched to 10 µm wide channels. Furthermore, it creates regions of differential protein adhesion, as shown by Coomassie staining and fluorescent labeling, and cell adhesion, as demonstrated by C2C12 myoblast growth. This method is simple, versatile, and allows biologists and bioengineers to manipulate regions for cell culture adhesion and growth. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 34:243-248, 2018.

Traumatic brain injury (TBI) affects 5.3 million people in the United States, and there are 12,500 new cases of spinal cord injury (SCI) every year. There is yet a significant need for in vitro models of TBI and SCI in order to understand the biological mechanisms underlying central nervous system (CNS) injury and to identify and test therapeutics to aid in recovery from neuronal injuries. While TBI or SCI studies have been aided with traditional in vivo and in vitro models, the innate limitations in specificity of injury, isolation of neuronal regions, and reproducibility of these models can decrease their usefulness in examining the neurobiology of injury. Microfluidic devices provide several advantages over traditional methods by allowing researchers to (1) examine the effect of injury on specific neural components, (2) fluidically isolate neuronal regions to examine specific effects on subcellular components, and (3) reproducibly create a variety of injuries to model TBI and SCI. These microfluidic devices are adaptable for modeling a wide range of injuries, and in this review, we will examine different methodologies and models recently utilized to examine neuronal injury. Specifically, we will examine vacuum-assisted axotomy, physical injury, chemical injury, and laser-based axotomy. Finally, we will discuss the benefits and downsides to each type of injury model and discuss how researchers can use these parameters to pick a particular microfluidic device to model CNS injury.

To create musculoskeletal tissue scaffolds for functional integration into host tissue, myotubes must be properly aligned with native tissue and spur the formation of neuromuscular junctions. However, our understanding of myoblast differentiation in response to structural alignment is incomplete. To examine how substrate anisotropy mediates myotube differentiation, we studied C2C12 myoblasts grown on aligned collagen substrates in the presence or absence of agrin. Myoblasts grown on microfluidically patterned collagen substrates demonstrated increased multinucleated myotubes and nicotinic acetylcholine receptor (AChR) clusters. However, agrin treatment did not synergistically increase differentiation of myoblasts seeded on these patterned collagen substrates. Myoblasts grown on aligned electrospun collagen nanofibres also demonstrated increased formation of multinucleated myotubes and AChR clusters, and agrin treatment did not increase differentiation of these cells. Using fluorescently labelled collagen nanofibres, we found that AChR clustered in cells grown on nanofibres with significantly higher anisotropy and that this clustering was eliminated with agrin treatment. Interestingly, anisotropy of substrate had no effect on the localization of AChRs along the myotube, suggesting that additional signalling pathways determine the specific location of AChRs along individual myotubes. Taken together, our results suggest a novel role for fibre anisotropy in myotube differentiation, specifically AChR clustering, and that anisotropy may guide differentiation by activating similar pathways to agrin. Our data suggest that agrin treatment is not necessary for differentiation and maturation of myoblasts into myotubes when myoblasts are grown on aligned collagen substrates.

Substrate and cell patterning techniques are widely used in cell biology to study cell-to-cell and cell-to-substrate interactions. Conventional patterning techniques work well only with simple shapes, small areas and selected bio-materials. This article describes a method to distribute cell suspensions as well as substrate solutions into complex, long, closed (dead-end) polydimethylsiloxane (PDMS) microchannels using negative pressure. This method enables researchers to pattern multiple substrates including fibronectin, collagen, antibodies (Sal-1), poly-D-lysine (PDL), and laminin. Patterning of substrates allows one to indirectly pattern a variety of cells. We have tested C2C12 myoblasts, the PC12 neuronal cell line, embryonic rat cortical neurons, and amphibian retinal neurons. In addition, we demonstrate that this technique can directly pattern fibroblasts in microfluidic channels via brief application of a low vacuum on cell suspensions. The low vacuum does not significantly decrease cell viability as shown by cell viability assays. Modifications are discussed for application of the method to different cell and substrate types. This technique allows researchers to pattern cells and proteins in specific patterns without the need for exotic materials or equipment and can be done in any laboratory with a vacuum.