Chuanwu Xi

Catheter-associated urinary tract infections (CAUTIs) are the most prevalent nosocomial infections. These infections impose a significant financial burden on the healthcare system and are responsible for approximately 15,000 deaths each year in the US. CAUTIs are caused by free-floating bacteria that adhere to the surface of Foley catheters and the patient’s uroepithelium, forming protective biofilms that enhance bacterial survival and resistance. In this study, a nitric oxide (NO)-releasing liquid formulation is used to inflate the Foley catheter balloon, aiming to inhibit biofilm formation and reduce the risk of CAUTIs. The solution of S-nitrosoglutathione (GSNO), an endogenous NO donor molecule, was used as the catheter inflation fluid. To assess the NO-release profile, the GSNO was dissolved in various pH-adjusted (pH 6.5) aqueous media (deionized water, phosphate-buffered saline, and 2-[4-(2-hydroxyethyl)piperazine-1-yl]ethanesulfonic acid [HEPES] buffers). The GSNO/HEPES formulation sustained NO fluxes through the inflated balloon wall above 0.5 × 10⁻¹⁰ mol·min⁻¹·cm⁻² for up to 10 days, as well as significantly reduced the planktonic bacteria counts and surface colonization against Escherichia coli . The safety of the optimized GSNO formulation was evaluated in vivo in a 7-day preclinical porcine model. The formulation showed no signs of NO-related toxicity. Overall, this study presents a promising, translatable approach to substantially reducing the risk of CAUTIs in healthcare settings. IMPORTANCE: Catheter-associated urinary tract infections (CAUTIs) are the most frequent hospital-acquired infections and pose serious risks for patients with Foley catheters in hospitals, nursing homes, and other care facilities. These infections lead to significant mortality and healthcare expenses and are especially difficult to prevent due to bacterial biofilms on catheter surfaces. Our study introduces a novel solution, a nitric oxide (NO)-releasing balloon inflation fluid using S-nitrosoglutathione (GSNO), that continuously releases antimicrobial NO for up to 10 days. This approach significantly reduces bacterial counts and surface colonization by Escherichia coli , a main cause of CAUTIs, while demonstrating safety in preclinical animal testing. Our findings suggest that this strategy could reduce infection risk and improve outcomes for catheterized patients across diverse healthcare settings.

Nanobubble technology has shown considerable promise in sustainable agriculture due to its ability to enhance seed germination, plant growth, and soil quality without leaving harmful residues. While benefits are often attributed to improved soil aeration and soil texture changes (e.g., permeability), nanobubbles may also influence soil microbiome, an essential driver of plant health and nutrient cycling. This study systematically investigated how different nanobubble types—oxygen, hydrogen, and carbon dioxide—modulate soil chemistry and microbial community structure over a 4-week period. Multivariate analyses on microbiome taxonomic composition revealed distinct microbial responses to each gas type. Oxygen and hydrogen nanobubble treatments resulted in more pronounced shifts in microbial composition and functional potential compared to carbon dioxide nanobubbles. These shifts included enrichment of bacterial taxa associated with nutrient turnover, pollutant degradation, and pathogen suppression, such as Flavobacteriaceae , Comamonadaceae , Nannocystaceae , and Blastocatellaceae . Functional predictions showed that oxygen and hydrogen nanobubbles could promote metabolic pathways related to organic compound degradation and remediation of contaminated soil. Microbial network analysis further highlighted the beneficial impacts of nanobubbles on keystone taxa, such as Flavobacteriaceae , which in turn play pivotal roles in shaping soil ecosystem functions. Together, these findings demonstrate that gas-specific nanobubble irrigation can steer soil microbiome dynamics in ways that may enhance soil fertility, resilience, and crop productivity. IMPORTANCE: This study provides new insights into how nanobubble irrigation can be used to improve soil health and agricultural sustainability. By demonstrating that oxygen and hydrogen nanobubbles selectively enrich beneficial microbial taxa linked to soil nutrient turnover, pollution degradation, and pathogen suppression, this study identifies a promising approach to enhance plant growth and soil health through new nanobubble-driven processes. The detection of keystone taxa responsive to nanobubble treatments also reveals potential microbial mechanisms underlying the interactions between nanobubbles, soil, and plant health. Together, these findings highlight nanobubble irrigation as a novel and scalable strategy for microbiome engineering that could advance sustainable crop production and environmental stewardship. Furthermore, while prior studies have primarily focused on the microbial effects of air and oxygen nanobubbles, our study systematically examined and compared the impacts of less explored nanobubble types, specifically hydrogen and carbon dioxide, demonstrating the broad versatility of nanobubbles for diverse agricultural applications.

Swimming-associated gastroenteritis at freshwater beaches have been linked to E. coli density, making continuous monitoring and source identification essential for water quality management. This study aimed to monitor fecal contamination in an inland lake over swimming seasons. Fecal contamination levels were assessed using culture-based E. coli counts and ddPCR assays (EC23S for E. coli, AllBac for Bacteroides spp.), while microbial source tracking markers (HF183 for human, ND2 for goose) were adopted to identify primary fecal sources. During the study period, ND2 was frequently detected and showed strong, consistent associations with culture-based E. coli (β = 0.297, p < 0.01; β = 0.323, p < 0.1) and AllBac gene concentrations (β = 0.216, p < 0.01; β = 0.166, p < 0.05). In contrast, HF183 levels were much lower and inconsistently related to fecal indicator bacteria (FIB). Model comparisons revealed that removing ND2 significantly reduced model performance, while HF183 had minimal explanatory power. This suggests that goose feces, rather than human waste, were the primary source of fecal contamination at the sampling sites. Additionally, the strong correlation observed between culture-based and ddPCR-based E. coli measurements (β = 0.41, p < 0.01; β = 0.64, p < 0.01) underscores the reliability of ddPCR as a viable tool for quantifying E. coli in recreational waters. Finally, the study highlights the importance of understanding location-specific effects on water quality and FIB levels.

Impact statement: COVID‐19 remains an ongoing threat to public health, and reliable, continuous disease monitoring programs are essential for preventing future surges of infection. However, without mandated COVID‐19 testing, accurate data of confirmed cases are unavailable. Instead, COVID‐19 viruses may be tracked via wastewater samples from sewage manholes in areas of high social connectivity, where captured viral RNA data are biomarkers useful for monitoring and predicting community‐level COVID‐19 prevalence through machine learning techniques. We construct a prediction model of high sensitivity and specificity to provide evidence of significant underreporting of COVID‐19 cases for the time period following the lifting of testing mandates.

Bioconversion of ammonium to dinitrogen (N2) is an essential process in the nitrogen cycle, primarily driven by O2-dependent nitrification and followed by O2-limited denitrification, involving multiple redox states of nitrogen (NH4+ → NH2OH → NO2− → NO3− → NO2− → NO→N2O → N2). Here, we discovered a new process termed acetone-mediated ammonium oxidation in Zobellella taiwanensis bacteria under both oxic and anoxic conditions, directly oxidizing ammonium to N2 (NH4+ + acetone → acetoxime → N2 + acetone). Acetone, produced from organic sources, couples with ammonium to form acetoxime in the presence of O2, NO2−, NO3−, or Fe(III). Subsequently, acetoxime is oxidized to N2, thereby releasing recyclable acetone. We purified two new enzymes (acetoxime synthase; acetoxime dehydrogenase) catalyzing this process and identified their corresponding genes. The widespread distribution of homologous amino acid sequences across thousands of prokaryotic and eukaryotic microorganisms suggests the potential ubiquity of this process in nature and its possible substantial contributions to the nitrogen cycle.

The aim of this work was to evaluate the efficacy of an organosilicon-based, commercially available antimicrobial formulation in the My-shield^® product line against bacterial surface contamination. The antimicrobial product was tested in vitro for its long-term persistence on surfaces and effectiveness against Staphylococcus aureus biofilms in comparison to 70% ethanol and 0.1% or 0.6% sodium hypochlorite. Field testing was also conducted over 6 weeks at a university athletic facility. In vitro studies demonstrated the log reductions achieved by the test product, 70% ethanol, and 0.1% sodium hypochlorite were 3.6, 3.1, and 3.2, respectively. The test product persisted on surfaces after washing and scrubbing, and pre-treatment with this product prevented S. aureus surface colonization for up to 30 days. In comparison, pre-treatment with 70% ethanol or 0.6% sodium hypochlorite was not protective against S. aureus biofilm formation after seven days. The field test demonstrated that weekly applications of the test product were more effective at reducing surface bacterial load than daily applications of a control product. The test product conferred greater long-term protection against bacterial growth and biofilm formation by S. aureus than ethanol and sodium hypochlorite. Even with less frequent applications, the test product maintained a high level of antimicrobial activity.

Although water stagnation is widely accepted as an essential factor supporting Legionella growth in plumbing systems and "water flashing" has become a common action for water quality control, additional monitoring data in practical spaces are still needed to back up this recommendation. The lockdown of public buildings during the COVID-19 pandemic provided an ideal time window to collect such data on a large scale. This study investigated how the long-term lockdown of a public building and the subsequent water stagnation impact water quality and the population of Legionella in water. From June 2020 to May 2021, 192 water samples were collected from a public building during the lockdown and reopening due to the COVID-19 pandemic. Each water sample was assessed for common physicochemical characteristics. Concentrations of Legionella and three species of free-living amoeba (FLA) (Acanthamoeba spp., Naegleria fowleri, and Hartmannella vermiformis) were monitored by qPCR. The data suggest that long-term stagnation promotes the population of Legionella spp., Acanthamoeba spp., and N. fowleri. Notable associations were observed between Legionella and FLA. These relationships were impacted by stagnation. These results provide important evidence that can inform future water quality management actions to minimize the risk of Legionella outbreaks by avoiding the occurrence of water stagnation.