Reemergence of Bordetella parapertussis, United States, 2019-2023.

To determine changes in Bordetella pertussis and B. parapertussis detection rates, we analyzed 1.43 million respiratory multiplex PCR test results from US facilities from 2019 through mid-2023. From mid-2022 through mid-2023, Bordetella spp. detection increased 8.5-fold; 95% of detections were B. parapertussis. While B. parapertussis rates increased, B. pertussis rates decreased.

Polymer Spreading on Unidirectionally Nanotextured Substrates Using Molecular Dynamics.

A unidirectional nanotexture alters the wettability of a substrate and can be used to create patterned polymer films, tailored polymer coverage/reflow, or aligned polymer molecules. However, the physical mechanisms underlying polymer spreading on nanoscale textures are not well-understood, and competing theories exist to explain how texture peaks and grooves alter the wettability of a substrate. We use molecular dynamics to simulate polymer spreading on substrates with unidirectional nanoscale textures as a function of texture shape and size and compare to polymer spreading on a flat substrate. We show that the texture groove shape is the primary factor that modifies polymer spreading on unidirectionally nanotextured substrates because the texture groove shape determines the minimum potential energy of a substrate. At the texture groove, the energy potentials of several surfaces combine, which increases polymer attraction and drives spreading along the texture groove. A texture groove also acts as a sink that inhibits polymer spreading perpendicular to the texture. Texture peaks create energy barriers that inhibit polymer spreading perpendicular to the texture, but this is a secondary mechanism that does not significantly affect anisotropic spreading. This research unifies competing theories of anisotropic liquid spreading documented in the literature and aims to aid in the design of nanoscale textures and ultrathin liquid film systems.

Polymer spreading on substrates with nanoscale grooves using molecular dynamics.

Understanding how liquid polymer interacts with and spreads on surfaces with nanoscale texture features is crucial for designing complex nanoscale systems. We use molecular dynamics to simulate different types of polymer as they spread on substrates with a single nanoscale groove. We study how groove design affects the potential energy of a substrate and how this governs polymer spreading and orientation. Based on our simulations, we show that groove shape, polymer chemistry, and polymer molecule entanglement are the three parameters that determine polymer spreading on a nanoscale groove. We provide a molecular-level explanation of the underlying physical mechanisms, and we illustrate this fundamental understanding by designing a network of grooves to engineer user-specified polymer spreading and coverage. This work has implications for nanoscale systems and devices that involve the design of complex groove networks with an ultrathin polymer coating, including micro and nanoelectromechanical devices, nanoimprint lithography, flexible electronics, antibiofouling coatings, and hard disk drives.

Spreading Kinetics of Ultrathin Liquid Films Using Molecular Dynamics.

Ultrathin liquid films play a critical role in numerous engineering applications. Although crucial to the design and application of ultrathin liquid films, the physical mechanisms that govern spreading on the molecular scale are not well-understood, and disagreement among experiments, simulations, and theory remains. We use molecular dynamics simulations to quantify the speed at which the edge of a polymer droplet advances on a flat substrate as a function of various environmental and design parameters. We explain the physical mechanisms that drive and inhibit spreading, identify different spreading regimes, and clarify transitions between spreading regimes. We demonstrate that the edge of a droplet spreads according to a power law with two distinct regimes, which we attribute to competing physical mechanisms: a pressure difference in the liquid droplet and molecule entanglement. This research unifies many years of liquid spreading research and has implications for systems that involve designing complex ultrathin liquid films.

The epidemiology of pediatric outpatient acute respiratory tract infections in the US: a multi-facility analysis of multiplex PCR testing from 2018 to 2023.

IMPORTANCE: Post-pandemic, it is essential to understand the epidemiology of pediatric acute respiratory tract infections (ARTIs). Our multi-facility study elucidates the outpatient epidemiology of pediatric ARTI using highly multiplexed PCR testing, providing critical insights into the evolving landscape of the etiological agents with a particular focus on the years following the emergence of SARS-CoV-2. Utilizing data from two different multiplex PCR panels, our research provides a comprehensive analysis of respiratory pathogen positivity from 2018 to 2023. Our findings indicate that over half of the annual test results identified at least one pathogen, primarily of viral origin. Intriguingly, despite the surge in testing during the COVID-19 pandemic, pathogen detection rates remain similar to the pre-pandemic era. These data hold significant implications for directing antimicrobial stewardship strategies, curbing unnecessary antibiotic use in pediatric respiratory diseases, and the value of multiplex PCR testing in the outpatient setting among pediatrics.

Candida auris rates in blood culture on the rise: results of US surveillance.

Candida auris is an emerging pathogen that poses a significant public health risk. Its multidrug resistance has led to high mortality, making rapid detection crucial for effective treatment and prevention of transmission. Recent data from the Centers for Disease Control and Prevention indicate a substantial increase in C. auris cases in the United States, with a 95% rise in 2021. To provide an update on the detection rates of C. auris, we analyzed blood culture results from a near real-time cloud-based surveillance network, BioFire Trend. From January 2021 to April 2023, 34 C. auris detections were observed. The analysis showed a notable increase in detections in 2023 compared to previous years. The detection rate in 2023 was higher in all four US Census Regions, except for the Northeast, where it remained constant. The findings emphasize the continuous rise in C. auris cases and highlight the importance of near real-time surveillance systems in monitoring this emerging pathogen.