Surface Disinfection Research Articles

UVC light as a strategy for disinfection of hospital air and surfaces

Objective: To evaluate a fixed UV-C light emitting device for its antimicrobial effectiveness in the disinfection of distinct surfaces and its antifungal effectiveness on air quality in the hospital environment. Methods: This quasi-experimental study was conducted in a hospital inpatient unit, in which a six-stage air Biosampler (Andersen®) was used for air analysis. In the evaluation of surfaces, three suspensions of microorganisms (Acinetobacter sp. multidrug-resistant, Escherichia coli, and KPC-producing Klebsiella pneumoniae) were used to contaminate the environment. In both evaluations, pre- (control) and post-activation of UV-C light (test) collections were made. Results: In the air evaluation, an important reduction was observed in the colony count after irradiation with UV-C light, and pathogenic or toxigenic fungi were not found in either of the two moments. Regarding the disinfection of surfaces, no bacterial growth was observed after the application of UV-C light, showing 100% bacterial inactivation under the tested conditions. Conclusion: The use of fixed UV-C light emission technology was effective and can be considered a promising intervention for hospital surface disinfection protocols.

High-Performance Acousto-Hydraulic method for generating fine aerosols for air and surface disinfection

Liquid atomization is utilized across various industrial applications, including nanopowder production, spray drying, fuel combustion, coating applications, emulsion preparation, and in medical devices. The use of ultrasonic energy for atomization offers advantages in terms of environmental sustainability compared to other methods. Notably, ultrasonic atomization can achieve finer dispersion with a narrow droplet size distribution at relatively low energy consumption, which is crucial for certain technological applications. One significant application of fine liquid atomization technology is in the disinfection of air and surfaces. The development of efficient and eco-friendly methods for air and surface disinfection has become particularly relevant in light of the spread of dangerous infections, such as the coronavirus. However, ultrasonic liquid atomization is characterized by low flow rate, limiting its applicability. The creation of a combined method that integrates the benefits of both ultrasonic and hydraulic atomization could enhance process efficiency while maintaining high droplet fineness. This study investigates the physical processes involved in cavitation-based aerosol formation and describes the design of an acousto-hydraulic atomizer for implementing the proposed combined atomization method. Theoretical and experimental analyses identified the critical conditions for the transition to the optimal spray mode and key characteristics of atomization. It was found that the simultaneous application of ultrasound and hydraulic pressure enables the production of fine sprays (with a minimum droplet diameters up to 45 µm) at high flow rates (10 ml/s or more). The study demonstrates that the new acousto-hydraulic atomization method can generate a disinfectant aerosol cloud at high speeds. This work highlights the method’s significant potential for sanitary measures, conducted with safety requirements in mind, thereby contributing to the preservation and improvement of public health globally.

Clinical and microbiological effectiveness of pulsed-xenon ultraviolet light disinfection in a neonatal intensive care unit in Japan

Meticillin-resistant Staphylococcus aureus (MRSA) is a common causative agent of serious healthcare-related infections in neonatal intensive care units (NICUs). In adult ICUs, pulsed-xenon ultraviolet (PX-UV) disinfection of environmental surfaces, along with alcohol-based hand hygiene and terminal cleaning, has been demonstrated to reduce the MRSA acquisition rate. However, the impact of PX-UV use in NICUs on reducing MRSA transmission remains unexplored. The incidence of newly detected MRSA cases was recorded for all patients between January 2021 and December 2022. UV irradiation was used in addition to terminal manual cleaning. During the baseline period, irradiation was performed on areas following the use by patients with MRSA, while in the intervention period, irradiation was performed after each patient's use. While there was no observed change in the frequency of hand hygiene compliance throughout the study period, the total number of MRSA cases detected per 1,000 patient days decreased significantly. In NICUs, UV irradiation of environmental surfaces, in addition to hand hygiene practices and conventional environmental maintenance, may be effective in reducing MRSA infection.

Inactivation of deposited bioaerosols on food contact surfaces with UV-C light emitting diode devices.

The airborne transmission of infectious diseases and bioaerosol-induced cross-contamination pose significant challenges in the food, dairy, and pharma industries. This study evaluated the effectiveness of 279 nm UV-C LED irradiation for decontaminating bioaerosols, specifically containing microorganisms such as Escherichia coli (C3040- Kanamycin resistant), Salmonella Enteritidis (ATCC 4931), and Pseudomonas fragi (ATCC 4973), on food contact surfaces. Borosilicate glass, silicon rubber, and stainless steel (316L) surfaces were selected for experimentation for their usage in the food industry. A 50 µL cell suspension was aerosolized at 25 psi pressure using a 4-jet BLAM Nebulizer within a customized glass chamber and then deposited onto the surface of the coupons. The serial dilution approach was used for the microbial enumeration, followed by duplicate plating. With a low Root Mean Square Error (RMSE) and high R2 values, the biphasic kinetic model for UV-C inactivation curves of all three pathogens demonstrated the excellent goodness of fit parameters. At a UV-C dose of 6 mJ cm-2, glass surfaces showed the maximum microbial inactivation (i.e., 2.80, 3.81, and 3.56 log CFU/mL for E. coli, Salmonella, and P. fragi, respectively). Stainless steel and silicon rubber surfaces showed significant microbial inactivation, but log10 reductions observed were consistently lower than glass surface. Our research indicates that UV-C LEDs (279 nm) can effectively disinfect bioaerosols on food contact surfaces.IMPORTANCEFood safety is a major public health concern, with contaminated food causing serious illnesses. UV-C light, used for germicidal action, is effective in disinfecting surfaces and is not subject to the same strict legal restrictions as chemical disinfectants, simplifying compliance with food safety regulations. In this study, we evaluated the efficacy of UV-C (279 nm) LED systems for inactivation of surface-deposited bioaerosols of kanamycin-resistant Escherichia coli (C3040), Salmonella Enteritidis (ATCC 4931), and Pseudomonas fragi (ATCC 4973). The research outcomes can be used to develop UV-based surface disinfection systems to minimize the risk of foodborne illnesses and enhance safety in high-traffic food preparation areas.

Irradiance modeling of tubular ultraviolet light bulbs

Clean indoor air is crucial for human lives in residential and workplace settings, including food safety and supply chains. Since the COVID-19 outbreak, disinfecting air has become vital for the public as the SARS-CoV-2 virus and other infectious diseases transmit via inhalable aerosols. Ultraviolet (UV) light is known to be effective in disinfecting air. However, it is still challenging to properly design practical UV applications with common light design software. Visible light analysis software, AGi32, assists architectural applications. AGi32 utilizes digitized luminaire IES files to model light intensity on user-designed geometry in common far-field uses. IES files are based on far-field photometry to model light intensity at different distances and angles from the source. The common application of IES files is to model visible light intensities; however, IES files generated for UV light are still rarely available. Due to the increasing need for surface and air disinfection, modeling UV light intensity using IES files may be beneficial for designing and evaluating systems containing UV light bulbs in near-field applications. There is limited information regarding the accuracy of UV modeling in AGi32 software using IES files. Therefore, the research objectives were to (1) create IES files of a UV-C germicidal lamp (254 nm) and a visible fluorescent lamp with almost identical metrics; (2) compare the IES files output with physical UV measurements inside and outside of an air duct; (3) develop correlations between light intensities of visible and UV light bulbs. Linear correlations were observed when comparing UV irradiance and visible illuminance for both measured and modeled data. The results indicated high variability between the measured and modeled light data, signifying the importance of further investigation of potential error sources and improving the accuracy of modeling.

Biofilm Inhibition Activity of Fennel Honey, Fennel Essential Oil and Their Combination.

The eradication of bacterial biofilms remains a persistent challenge in medicine, particularly because an increasing number of biofilms exhibit resistance to conventional antibiotics. This underscores the importance of searching for novel compounds that present antibacterial and biofilm inhibition activity. Various types of honey and essential oil were proven to be effective against a number of biofilm-forming bacterial strains. The current study demonstrated the effectiveness of the relatively unexplored fennel honey (FH), fennel essential oil (FEO), and their combination against biofilm-forming bacterial strains Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus, and Escherichia coli, with a series of in vitro experiments. The authenticity of FH and FEO was checked with light microscopy and gas chromatography-mass spectrometry, respectively. Minimum inhibitory concentrations were determined using the microdilution method, and antibiofilm activity was assessed with crystal violet assay. Structural changes in bacterial cells and biofilms, induced by the treatments, were monitored with scanning electron microscopy. FEO and FH inhibited the biofilm formation of each bacterial strain, with FEO being more effective compared to FH. Their combination was the most effective, with inhibitory rates ranging between 87 and 92%, depending on the bacterial strain. The most sensitive bacterium was E. coli, while P. aeruginosa was the most resistant. These results provide justification for the combined use of honey and essential oil to suppress bacterial biofilms and can serve as a starting point to develop an effective surface disinfectant with natural ingredients.

Air Plasma Jet Generation Apparatus "ALOE" A.V. Kazak, L.V. Simonchik

The article presents an apparatus for generating an air plasma jet "ALOE". The device differs from known analogues in its compactness achieved due to absence of need to use inert gases (because they are replaced by ambient air) and the ability to determine the exposure dose. In terms of its characteristics this new product corresponds to world standards. There are no domestic analogues of it. Parameters and examples of using this device are presented. It will be in demand for healthcare, veterinary medicine, and cosmetology. The device can be used for disinfection of surfaces, including heat-sensitive ones, such as living tissues, and can serve as a prototype for development of various physiotherapeutic devices.

Inhibitory Effect of DNase-Chitosan-Nisin Nanoparticles on Cell Viability, Motility, and Spatial Structures of Listeria monocytogenes Biofilms.

Listeria monocytogenes biofilm contamination on food contact surfaces is a major concern for the food industry. Nanoparticle encapsulation appears as a novel strategy for food surface disinfection to prevent biofilm formation. Chitosan nanoparticles loaded with nisin and DNase I (DNase-CS-N) have been constructed to exhibit antimicrobial activity against L. monocytogenes. This study aimed to investigate their ability to inhibit L. monocytogenes biofilm formation and eliminate preformed biofilms on food contact surfaces (polystyrene, polyurethane, and stainless steel). DNase-CS-N could decrease 99% and 99.5% biofilm cell numbers at 1/2 MIC and MIC, respectively. At sub-MICs, DNase-CS-N could reduce cell motility (swimming and swarming) and slime production of L. monocytogenes. In terms of effect on biofilm elimination, DNase-CS-N at the concentration of 4 MIC led to 3-4 log reduction in biofilm cells in preformed biofilms, performing higher efficiency compared with other treatments (CSNPs, CS-N). Furthermore, the three-dimensional structure of L. monocytogenes biofilms was severely disrupted after DNase-CS-N treatment, with bacterial cells scattered on the surface. The morphology of biofilm cells was also greatly damaged with wrinkled surfaces, disrupted cell membranes, and leakage of intracellular nucleic acids and proteins. These results indicate the potential applicability of DNase-CS-N for inhibiting and eliminating L. monocytogenes biofilms on food contact surfaces.

Environmental pH and compound structure affect the activity of short-chain carboxylic acids against planktonic growth, biofilm formation, and eradication of the food pathogen Salmonella enterica.

Short-chain carboxylic acids (SCCAs) that are naturally produced by microbial fermentation play an essential role in delaying microbial spoilage. SCCAs are structurally diverse, but only a few of them are routinely used in food biopreservation. This study investigated the effects of environmental pH and intrinsic properties of 21 structurally different SCCAs on the antimicrobial and antibiofilm activity against Salmonella enterica. Inhibition of SCCA toward planktonic and biofilm growth of S. enterica was higher in an acidic environment (pH 4.5) that is common in fermented products, and for SCCA that possessed both a high acid dissociation strength (pKa) (>4.0) and a positive hydrophobicity [octanol/water partition coefficient (log Kow)]. Crotonic and caproic acids were identified as SCCAs with potential as biopreservatives even at near-neutral pH. SCCA with hydrophilic groups such as lactic acid did not inhibit S. enterica at concentrations up to 50 mM, while SCCA with benzene or methyl groups or a double bond prevented S. enterica growth and biofilm formation. Stimulation of biofilm formation was observed for formic, acetic, and propionic acid close to the minimum inhibitory concentration to reduce 50% of cell density (MIC50) of planktonic cells, and for citric and isocitric acid with an MIC50 of ≥50 mM. The presence of low concentrations of formic and propionic acids during biofilm formation conferred protection during eradication possibly due to a pre-adaptation effect, yet two consecutive acid treatments were successful in eradicating biofilms if the first acid treatment was two- to threefold of the MIC50.IMPORTANCEThis study provides a systematic comparison on the antimicrobial and antibiofilm activity of more than 20 structurally different SCCAs against a common food pathogen. We tested the antimicrobial activity at controlled pH and identified the structure-dependent antimicrobial effects of SCCA without the confounding influence of acidification. The combined effect of pKa and log Kow was identified as an important feature that should be considered when deciding for a specific SCCA in the application as antimicrobial. Our results imply that additional phenomena such as the use of SCCA as substrate and cellular pre-adaption effects have to be taken into consideration. We finally present a two-step treatment as an efficient approach to eradicate biofilms, which can be applied for the disinfection of contact surfaces and manufacturing equipment. Results obtained here can serve as guidelines for application of SCCA to avoid the growth of food pathogens and/or to develop biopreserved food systems.

Cleaning and Disinfection of Surfaces in a COVID-19 Respiratory Syndrome Unit: A Quasi-Experimental Study

Objective: This study aimed to assess the impact of an educational intervention on the cleaning and disinfection processes within a respiratory syndrome unit, serving as a designated facility for COVID-19 patients. Methods: A quasi-experimental design was employed, incorporating a pre-intervention and postintervention assessment. The evaluation of surfaces involved various monitoring techniques, including Adenosine Triphosphate (ATP) testing, colony-forming unit analysis, and visual inspections. All statistical analyses were conducted at a significance level of 5% (p < 0.05). Results: Following the implementation of the educational intervention, a notable reduction in surface contamination rates was observed. Significant improvements were noted for specific surfaces when utilizing the ATP testing method, including benchtops (p = 0.030), mattresses (p = 0.014), doorknobs (p = 0.014), and armchairs (p = 0.014). Furthermore, a decrease in the total count of aerobic bacteria was observed for benchtops (p = 0.014), mattresses (p = 0.014), and doorknobs (p = 0.014). Visual inspection results also indicated enhancements, with approval rates for benchtops, armchairs, and mattresses rising from 0% before the intervention to 37.5% afterward. Conclusion: The findings of this study demonstrate substantial improvements in approval rates following the implementation of the educational intervention. Additionally, this research provides valuable insights for the development of ongoing educational initiatives for the healthcare team, incorporating evaluation and feedback mechanisms as well as updates to cleaning and disinfection protocols.

Neutrophil-inspired Zn and Zn@ZnO microparticles decorated with Cu nanoparticles self-release oxidized halogen antimicrobials

Oxidized halogen antimicrobials, such as hypochlorous acid, have been widely used for microbial control, successfully eliminating waterborne diseases like cholera, typhoid, dysentery, and hepatitis A in developed countries. During the COVID-19 pandemic, these acids were used extensively for air and surface disinfection. However, they require repeated applications as they only offer one-time disinfection. To address this issue, we have developed Cu nanoparticles decorated Zn and Zn@ZnO (denoted as Zn@Cu and Zn@ZnO/Cu), mimicking the neutrophils NADPH oxidase (NOX) system. This novel system utilizes zinc metal to produce H2O2, and a catalytic copper shell to convert H2O2 and Cl−/Br−/I− to hypohalous acid, which has good antimicrobial and antiviral properties along with enhanced durability. The addition of Zn@Cu onto painted surfaces shows good disinfection properties. The application of Zn@ZnO/Cu in diabetic wound healing yields superior outcomes to the conventional silver-based commercial products.

WITHDRAWN: Vitrification-cryopreservation of shoot tips excised from dormant bulbs in Fritillaria przewalskii maxim: Assessing histological injuries and evaluating genetic fidelity in cryo-derived plants

Fritillaria przewalskii Maxim. an essential medicinal plant in the Fritillaria genus of the Liliaceae family, is widely used in traditional medicine. This study focused on developing a cryopreservation protocol for F. przewalskii, an endangered and endemic species in China. We aimed to determine if ex vitro bulbs from field-grown F. przewalskii plants could serve a source of shoot tips for cryopreservation. Key factors influencing cryopreservation outcomes were studied using a vitrification-based approach. Prior to cryopreservation, cold hardening and sucrose preculture conditions were optimized. The best results were achieved by hardening bulbs at 4℃ for 3-4 months,followed by surface disinfection and isolation of 2-5mm Shoot tips. The tips were then then precultured on a medium with 0.5M sucrose for 3 days. Cryopreservation steps included a 20-minute loading treatment, 60-minute PVS2 dehydration at room temperature, and storage in liquid nitrogen more than one hour. After thawing, this protocol resulted in 93% shoot survival rate, with tips regenerating into small bulbs within 5 weeks without intermediary callus formation. Histological analysis showed that while cooling and rewarming caused severe bud damage, apical meristem cells are the primary survival sites. Although loading and PVS2 treatment induced cell plasmolysis, it was not lethal. Optimal PVS2 treatment enhanced cellular dehydration resistance, promoting cell viability at ultralow temperature. RAPD analysis of regenepercentaged plants showed no genetic variation, confirming strong genetic stability. The direct use of ex vitro shoot tips provides a straightforward and effective cryopreservation method for F. przewalskii, combining convenience, efficiency, and genetic stability.

Standard Methods for Evaluating Electrostatic Spray Charge and Deposition of Conductive Liquids Used for Surface Disinfection

Standard Methods for Evaluating Electrostatic Spray Charge and Deposition of Conductive Liquids Used for Surface Disinfection

Efficacy of Disinfectants for Monkeypox Virus Inactivation on High Touch Surface Materials in Low-Resource Settings.

Disinfection efficacy tests were conducted on surface carriers inoculated with the monkeypox virus (MPXV) by applying six disinfectant solutions (and three controls) on six surfaces common in low-resource settings: four nonporous surfaces (stainless steel, glass, plastic, and latex) and two porous surfaces (ceramic and wood). Disinfectants were wiped on carriers in triplicate, with a 1 min contact time: 0.05 and 0.5% sodium hypochlorite, 70% ethanol, two quaternary ammonium compound (QAC)-based disinfectants, and 1.4% hydrogen peroxide. MPXV was then quantified, and log10 removal values were calculated. Sodium hypochlorite (0.05 and 0.5%) and ethanol (70%) removed MPXV to below detection level, ≥ 99.97% reduction for nonporous surfaces, and ≥99.40% for wood, QAC-based disinfectants were efficacious on nonporous surfaces (≥99.97% inactivation) but had diminished efficacy on wood, a porous surface, and 1.4% H2O2 had limited efficacy across all tested surfaces. Results varied by disinfectant type and surface type. Based on our results, we recommend using 0.05% sodium hypochlorite or 70% ethanol with 1 min contact time to inactive MPXV on clean nonporous and porous surfaces. As MPXV is evolving, future research with additional disinfectants, application methods, and environmental conditions and research to understand adsorption, disinfection efficacy, and transmission risk on porous surfaces are needed to develop practical disinfection recommendations.

Antimicrobial surface coating in the emergency department as protective technology for infection control (ASEPTIC): a pilot randomized controlled trial

Study objectiveWe examined the effectiveness of an antimicrobial surface coating for continual disinfection of high touch-frequency surfaces in the emergency department (ED).MethodsFollowing a preliminary observation identifying stretcher rails as the surface with highest touch-frequency in the ED, we conducted a pilot randomized controlled trial involving 96 stretcher rails. The stretchers were randomized to receive an antimicrobial surface coating or placebo coating. Routine cleaning of stretchers subsequently continued as per hospital protocol in both arms. Sampling for total aerobic, gram-positive halophilic, gram-negative and methicillin-resistant Staphylococcus aureus bacteria was performed pre- and post-treatment at 24 h, 7 days and 180 days. Individuals who applied the coating and outcome assessors were blinded to the allocated arms. The primary outcome is contamination of antimicrobial versus placebo rails measured as colony forming units per cm2(CFU/cm2).ResultsBaseline total aerobic bacteria was comparable between placebo and intervention arms (0.84 versus 1.32 CFU/cm2, P = 0.235). Total aerobic bacteria contamination was significantly lower on antimicrobial versus placebo rails at 24 h (0.61 versus 1.01 CFU/cm2, median difference 0.40 CFU/cm2, 95% confidence interval [CI] 0.01 to 1.01 CFU/cm2). There was a non-statistically significant tendency for contamination to be lower on antimicrobial versus placebo rails at 7 days (1.15 versus 1.50 CFU/cm2, median difference 0.35 CFU/cm2, 95% CI -0.64 to 1.28 CFU/cm2), but higher at 180 days (2.06 versus 1.84 CFU/cm2, median difference − 0.22 CFU/cm2, 95% CI -1.19 to 0.78 CFU/cm2).ConclusionThis is the first double-blinded, placebo-controlled, randomized trial to evaluate an antimicrobial surface coating on high touch-frequency surfaces in the emergency department. Total aerobic bacteria found on antimicrobial-coated patient transport stretcher rails was significantly lower than placebo rails at 24 h.

The application of ozone within the food industry, mode of action, current and future applications, and regulatory compliance.

The food industry faces numerous challenges today, with the prevention and reduction of microbial contamination being a critical focus. While traditional chemical-based methods are effective and widely used, rising energy costs, the development of microbial tolerances, and growing awareness of the ecological impact of chemical biocides have renewed interest in novel biocides. Ozone, in both its gaseous and aqueous forms, is recognized as a potent disinfectant against bacteria, viruses, and fungi due to its high oxidation potential. Our review highlights several studies on the applications of ozone within the food industry, including its use for surface and aerosol disinfection and its capacity to reduce viable Listeria monocytogenes, a pertinent foodborne pathogen harbouring environmental and biocide stress tolerances and biofilm former. We also explore the use of ozone in food treatment and preservation, specifically on blueberries, apples, carrots, cabbage, and cherry tomatoes. While ozone is an effective disinfectant, it is important to consider material incompatibility, and the risks associated with prolonged human exposure to high concentrations. Nevertheless, for certain applications, ozone proves to be an efficacious and valuable alternative or complementary method for microbial control. Compliance with the biocide products regulation will require ozone device manufacturers to produce proven efficacy and safety data in line with British standards based on European standards (BS EN), and researchers to propose adaptations to account for ozone's unique properties.

Bushy-Tailed Multicationic Quaternary Phosphonium Compounds: Potent Amphiphilic Disinfectants with Promising Therapeutic Indices.

Quaternary ammonium compounds (QACs) have been essential for protecting human health for almost a century, functioning as surface disinfectants and sanitizers. With bacterial resistance increasing against commercially available QACs, the development of novel antimicrobials with divergent architectures is essential for effective infection prevention and control. Toward this end, our group has expanded beyond traditional ammonium scaffolds and explored the development of quaternary phosphonium compounds (QPCs). Herein, we report the synthesis and biological investigation of a series of 20 novel multicationic QPCs, bearing multiple short alkyl or aryl chains, also referred to as "bushy-tailed" multiQPCs; these structures were hypothesized to have strong bioactivity while displaying low mammalian toxicity. Select bushy-tailed QPC derivatives with trishexylphosphonium groups displayed single-digit or sub-micromolar activity against all seven bacteria tested, and MIC values of 2- to 8-fold better than their bushy-tailed QAC counterparts. Importantly, therapeutic indices of these bushy-tailed QPCs were favorable in many cases, and were ≥ 4 against the entire bacterial panel for pX-P6*,P6* and 1,8-P6*,P6*, superior to more traditional architectures. This work highlights the promise of a novel set of multicationic phosphonium compounds as novel disinfectants with potent bioactivities and low toxicity.

Assessing effectiveness of cleaning and disinfection of equipment and environmental surfaces in cystic fibrosis clinics using an ATP assay.

Infection control guidelines for cystic fibrosis (CF) stress cleaning of environmental surfaces and patientcare equipment in CF clinics. This multicenter study measured cleanliness of frequently touched surfaces in CF clinics using an ATP bioluminescence assay to assess the effectiveness of cleaning/disinfection and the impact of feedback. Eight surfaces were tested across 19 clinics (10 pediatric, 9 adult) over 5 rounds of testing. Rounds 1 and 2 served as uncleaned baseline, and Round 3 occurring after routine cleaning. Rounds 4 and 5 were performed after feedback provided to staff and measured after cleaning. Pass rates defined as <250 relative light units were the primary outcome. Of the 750 tests performed, 72% of surfaces passed at baseline, and 79%, 83%, and 85% of surfaces passed in Rounds 3, 4, and 5, respectively. The overall pass-rate was significantly higher in adult compared to pediatric clinics (86% vs 71%; P < 0.001). In pediatric clinics, blood pressure equipment and computer keyboards in the pulmonary function lab consistently passed, but the exam room patient/visitor chairs consistently failed in all rounds. In adult clinics blood pressure equipment, keyboards in exam rooms and exam tables passed in all rounds and no surface consistently failed. We demonstrate the feasibility of an ATP bioluminescence assay to measure cleanliness of patient care equipment and surfaces in CF clinics. Pass rates improved after cleaning and feedback for certain surfaces. We found that surfaces are more challenging to keep clean in clinics taking care of younger patients.

Simultaneous treatment with tap water-based neutral electrolyzed water and citric acid for inactivating foodborne pathogens on stainless steel and their synergistic bactericidal mechanisms

Electrolyzed water has many potential applications, the primary one being the eliminating microorganisms in the food industry. However, this application is limited by high chlorine levels. Tap water-based neutral electrolyzed water (TNEW) has the advantage of relatively low chlorine concentration (1.7–4.6 mg/L), but its sterilization effect is limited. In this study, TNEW was combined with citric acid (CA) solution, resulting in strong synergistic inactivation effect on Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes on stainless steel surfaces. Simultaneous treatment of stainless steel with TNEW [available chlorine concentration (ACC) of 4.97 mg/L] and 0.1% CA for 15 min resulted in 4.78-, 4.26-, and >5.69 log CFU/cm2 surface reduction in E. coli O157:H7, S. Typhimurium, and L. monocytogenes, respectively, which was a synergistic cell count reductions of 3.25, 2.83, and >3.84 log units, respectively. Fluorescence and RT-qPCR analyses identified synergistic production of intracellular reactive oxygen species (ROS), damage to the cell membrane resulting from lipid peroxidation, and DNA damage as the major factors contributing to the synergistic lethal effect. The results of this study suggest that the TNEW–CA combination treatment can be applied as a potential substitute for conventional electrolyzed water treatment for food contact surface disinfection.

First report of Botryosphaeria dothidea causing root rot of sugar beet in Serbia.

Botryosphaeria dothidea (Moug.:Fr.) Ces. & De Not. is predominantly recognized as a pathogen of various woody plants, inducing symptoms of stem canker, dieback, and fruit rot worldwide. However, sporadic reports suggest its impact on field crops, including B. dothidea associated with stem canker in soybean and tobacco (Bian et al. 2015; Chen et al. 2021), as well as B. quercuum on sugar beet (Alfieri et al. 1984). In September 2023, during a survey of root rot pathogens of sugar beet (Beta vulgaris L.) in Rimski Šančevi, Serbia (N 45°19´57″; E 19°49'58″), 3% of collected samples exhibited root rot symptoms. Externally, the lesions exhibited a dark brown coloration. On cross-section, the tissue displayed a gradient of discoloration ranging from light to dark brown throughout the roots. The roots were completely rotted. From these samples, two fungal isolates (SR28/II and SR4/III) were obtained from rotted internal root fragments, after washing, surface disinfection (70% ethanol), and plating on potato dextrose agar (PDA). Colonies on PDA were fluffy with abundant aerial mycelium, surface light to dark grey-brown, reverse black in the centre and grey-brown towards the irregular margin, after 7 days at 25°C in the dark. To induce sporulation, isolates were cultivated on 2% water agar with pine needles and incubated under continuous near ultraviolet (NUV) light at room temperature for 30 days. Conidia were hyaline, aseptate, fusiform, subtruncate at the base, subobtuse at the apex, and measured (19.56-) 24.12 - 26.31 (-28.99) x (5.13-) 5.94 - 6.54 (-7.44) µm (mean 25.06 x 6.26 µm, n=100), consistent with description of B. dothidea (Phillips et al. 2013). For molecular identification, DNA was extracted from mycelium of 7-day-old cultures, and internal transcribed spacer region (ITS), partial translation elongation factor 1-alpha gene (TEF) and partial β-tubulin gene (TUB) were amplified using the primer pairs ITS1/ITS4 (White et al. 1990), EF1-728F/EF1-986R (Carbone and Kohn 1999), and Bt2a/Bt2b (Glass and Donaldson 1995), respectively. Multiple sequence alignment and BLAST analyses showed that our isolates had 100% sequence similarity with reference isolates of B. dothidea, including ex-type isolate CBS 115476 (= CMW 8000) in ITS (AY236949), TEF (AY236898), and TUB (AY236927). Maximum likelihood phylogeny of concatenated sequences confirmed the identity of the isolates as B. dothidea. Sequences of ITS, TEF and TUB of isolate SR4/III were submitted to GenBank under accession numbers PP908658, PP911334, PP911333, respectively. The pathogenicity of obtained isolates was assessed on 3-month-old sugar beet plants grown in sterile substrate in the greenhouse. For inoculation, the upper parts of the roots were wounded (10x3 mm) 1 cm above the substrate, using a sterilized nail, and 2x2 mm mycelial plugs of 7-day-old culture grown on PDA were inserted and sealed with parafilm. Control plants were inoculated with sterile PDA plugs. Six plants were used per isolate and for control. After 3 weeks of incubation, the inoculated plants were removed from the substrate and brown rot symptoms were observed upon cross-sectional examination, whereas control roots remained asymptomatic. The pathogen was successfully reisolated and morphologically identified as B. dothidea, fulfilling Koch's postulates. The production of sugar beet, an important industrial crop in Serbia valued for its sugar content, is imperiled by various pathogens. To our knowledge, this is the first report of B. dothidea causing root rot of sugar beet in Serbia and the world. Given its widespread distribution on other hosts and potential aggressiveness, the presence of B. dothidea in sugar beet should not be neglected.