Decontamination Methods Research Articles

Testing the effectiveness of different wash protocols to remove body surface contaminants in invertebrate food web studies.

Molecular gut content analysis via diagnostic PCR or high-throughput sequencing (metabarcoding) of consumers allows unravelling of feeding interactions in a wide range of animals. This is of particular advantage for analyzing the diet of small invertebrates living in opaque habitats such as the soil. Due to their small body size, which complicates dissection, microarthropods are subjected to whole-body DNA extraction-step before their gut content is screened for DNA of their food. This poses the problem that body surface contaminants, such as fungal spores may be incorrectly identified as ingested food particles for fungivorous species. We investigated the effectiveness of ten methods for body surface decontamination in litter-dwelling oribatid mites using Steganacarus magnus as model species. Furthermore, we tested for potential adverse effects of the decontamination techniques on the molecular detection of ingested prey organisms. Prior to decontamination, oribatid mites were fed with an oversupply of nematodes (Plectus sp.) and postmortem contaminated with fungal spores (Chaetomium globosum). We used diagnostic PCR with primers specific for C. globosum and Plectus sp. to detect contaminants and prey, respectively. The results suggest that chlorine bleach (sodium hypochloride, NaClO, 5%) is most efficient in removing fungal surface contamination without significantly affecting the detection of prey DNA in the gut. Based on these results, we provide a standard protocol for efficient body surface decontamination allowing to trace the prey spectrum of microarthropods using molecular gut content analysis.

Inactivation of human coronaviruses using an automated room disinfection device

The emergence of more virulent and epidemic strains of viruses, especially in the context of COVID-19, makes it more important than ever to improve methods of decontamination. The objective of this study was to evaluate the potential of on-demand production of chlorine species to inactivate human coronaviruses. The commercial prototype disinfection unit was provided by Unipolar Water Technologies. The Unipolar device generates active chlorine species using an electrochemical reaction and dispenses the disinfectant vapour onto surfaces with an aspirator. The minimum effective concentration and exposure time of disinfectant were evaluated on human hepatoma (Huh7) cells using 50% tissue culture infectious dose (TCID50) assay and human coronavirus 229E (HCoV-229E), a surrogate for pathogenic human coronaviruses. We showed that chlorine species generated in the Unipolar device inactivate HCoV-229E on glass surfaces at ≥ 400 parts per million active chlorine concentration with a 5 min exposure time. Here, inactivation refers to the inability of the virus to infect the Huh7 cells. Importantly, no toxic effect was observed on Huh7 cells for any of the active chlorine concentrations and contact times tested.

Decontamination and Repair Protocol Promotes Positive Outcomes in Implants Affected by Peri-implantitis: A Human Case Series.

This study assessed the effectiveness and predictability of a readily available protocol to treat peri-implantitis utilizing mechanical debridement, chemical antiseptic surface detoxification, and osseous grafting. Nine patients (7 women, 2 men; mean age: 56.5 years) with 15 implants with peri-implantitis were included. Pocket probing depth (PPD), bleeding on probing (BOP), and standardized digital periapical radiographic measurements were taken. Surgical flaps were elevated, and the implant threads were cleaned with a plastic curette. Chemical decontamination was performed by scrubbing solutions of 0.25% sodium hypochlorite (NaClO) and 1.5% hydrogen peroxide (H2O2) around the exposed implant using cotton pellets. Bony defects were filled with a 50/50 mixture of bovine hydroxyapatite and nanocrystalline calcium sulfate (CaSO4). A porcine collagen membrane was placed over the grafted bony defect. Follow-up appointments were scheduled 1 week, 2 weeks, 3 months, 6 months, 9 months, and 1 year posttreatment. Clinical and radiographic parameters were assessed and compared. At baseline, PPD ranged from 5 to 7.5 mm (mean: 6 ± 0.7 mm). At 12 months, PPD ranged from 1.5 to 4.2 mm (mean: 2.5 ± 0.8 mm). The mean PPD reduction of 3.6 mm (59.2%) was statistically significant (P < .001). The number of bleeding sites around each test implant decreased significantly from 4 to 0.4 sites between baseline and 12 months (P < .001). Mean radiographic bone loss decreased from 4.8 ± 1.3 mm to 2.7 ± 1.2 mm (P < .001). The proposed method of mechanical decontamination, chemical detoxification, and bone regeneration is clinically effective and reproducible. Clinical peri-implant parameters and radiographic bone levels were improved and maintained their stability for 1 year using this peri-implantitis treatment protocol.

Dynamic Thermal Treatments in Green Coconut Water Induce Dynamic Stress Adaptation of Listeria innocua That Increases Its Thermal Resistance.

The global coconut water market is projected to grow in the upcoming years, attributed to its numerous health benefits. However, due to its susceptibility to microbial contamination and the limitations of non-thermal decontamination methods, thermal treatments remain the primary approach to ensure the shelf-life stability and the microbiological safety of the product. In this study, the thermal inactivation of Listeria innocua, a Listeria monocytogenes surrogate, was evaluated in coconut water and in tryptone soy broth (TSB) under both isothermal (50-60 °C) and dynamic conditions (from 30 to 60 °C, with temperature increases of 0.5, 1 and 5 °C/min). Mathematical models were used to analyse the inactivation data. The Geeraerd model effectively described the thermal inactivation of L. innocua in both TSB and coconut water under isothermal conditions, with close agreement between experimental data and model fits. Parameter estimates and analysis revealed that acidified TSB is a suitable surrogate medium for studying the thermal inactivation of L. innocua in coconut water, despite minor differences observed in the shoulder length of inactivation curves, likely attributed to the media composition. The models fitted to the data obtained at isothermal conditions fail to predict L. innocua responses under dynamic conditions. This is attributed to the stress acclimation phenomenon that takes place under dynamic conditions, where bacterial cells adapt to initial sub-lethal treatment stages, leading to increased thermal resistance. Fitting the Bigelow model directly to dynamic data with fixed z-values reveals a three-fold increase in D-values with lower heating rates, supporting the role of stress acclimation. The findings of this study aid in designing pasteurization treatments targeting L. innocua in coconut water and enable the establishment of safe, mild heat treatments for refrigerated, high-quality coconut water.

Recent Advances in Biodecontamination of Aflatoxins in Foodstuffs: Using Biomass (2011-2021)

Background: Aflatoxin is one of the most hazardous toxins produced by Aspergillus spp. and contaminates animal feed and therefore human food. Aflatoxin exposure causes several health problems including liver, kidney, and intestine disorders for human beings. Therefore, an efficient decontamination method for food stuff seems essential. Objective: The aim of this mini-review was to go over the recent advances in the decontamination of aflatoxins in foodstuffs and explain the bio-removal methods based on microorganisms during the last decade. Methods: Literature research was performed using the keywords “aflatoxin”, “bio removal”, “decontamination”, “food”, and “biomass” individually or all together, in Scopus, Web of Science, and Pubmed in the last decade. Results: LABs and yeasts are the most useful and successful microorganisms in this field. These methods are very efficient, specific, environmentally friendly, and cost-effective, also they do not affect the nutritional value of the foodstuffs, unlike the physical or chemical techniques. The bio-removal methods contain aflatoxin adsorption and degradation. Conclusion: Although more studies and researches are required to evaluate the different types of toxin removal using various microorganisms and their practical aspects and the highest efficiency should be determined.

Experimental Study for the Evaluation of Titanium Disc Decontamination and Osseointegration in the Rabbit Tibia Model

Peri-implantitis is an inflammatory lesion leading to bone destruction resulting from bacterial infection and biofilm formation. Treatments of peri-implantitis aim at bacterial controls and decontamination to promote re-osseointegration. The present study aimed to assess the decontamination of biofilm and the osseointegration of titanium discs in a rabbit tibia model. Discs were immersed in culture medium inoculated with Staphylococcus aureus and incubated at 37 °C for 24 h and allocated to different treatments (n = five per group). The decontamination methods were an air-polishing system, 0.12% chlorhexidine rinse, and Er:Yag laser treatments. Each disc from the experimental groups was observed using scanning electron micrography. The rest of the discs were then implanted in four male New Zealand rabbits. Histological and radiographic evaluations were performed. For the quantification of bone density in radiographic data, the fractal dimension (FD) and mean grayscale value (GV) were measured. The Kruskal–Wallis test was used to compare bone density (p &lt; 0.05). Statistically significant differences in FD were observed between the air-polishing treatment with chlorhexidine rinse and the air-polishing treatment with chlorhexidine rinse and Er:Yag laser treatment compared to the contaminated group (p &lt; 0.05). Also, there were statistically significant differences in the results obtained for the group undergoing air-polishing treatment with chlorhexidine rinse and Er:Yag laser treatment compared to the contaminated group (p &lt; 0.05). The decontamination method using air polishing treatment, chlorhexidine rinse, and Er:Yag treatment showed favorable osseointegration with good bone quality.

AKmerBroom: Ancient oral DNA decontamination using Bloom filters on k-mer sets

Dental calculus samples are modeled as a mixture of DNA coming from dental plaque and contaminants. Current computational decontamination methods such as Recentrifuge and DeconSeq require either a reference database or sequenced negative controls, and therefore have limited use cases. We present a reference-free decontamination tool tailored for the removal of contaminant DNA of ancient oral sample called aKmerBroom. Our tool builds a Bloom filter of known ancient and modern oral k-mers, then scans an input set of ancient metagenomic reads using multiple passes to iteratively retain reads likely to be of oral origin. On synthetic data, aKmerBroom achieves over sensitivity and specificity. On real datasets, aKmerBroom shows higher read retainment ( on average) than other methods. We anticipate aKmerBroom will be a valuable tool for the processing of ancient oral samples as it will prevent contaminated datasets from being completely discarded in downstream analyses.

Effect of ScCO2 on the decontamination of PECs-based cryogels: A comparison with H2O steam and H2O2 nebulization methods

Biopolymers present ideal properties to be used in wound dressing solutions. By mixing two oppositely charged macromolecules it is possible to form polyelectrolyte complex (PEC) based cryogels using lyophilization. Their application in the biomedical field is limited due to their sterilization requirements, as conventional methods compromise their physicochemical properties. ScCO2 appears as an alternative method for decontamination. This work assessed several cryogel PEC formulations, chitosan-pectin, gelatine-xanthan gum and alginate-gelatine. PEC formation was confirmed by FTIR and rheological analysis. While steam sterilization compromised cryogels’ chemical and morphological properties, decontamination with scCO2 proved to be a promising method for decontamination of PEC-cryogels, because, similarly to what is observed with hydrogen peroxide, it does not compromise their physicochemical properties.

L. pneumophila resists its self-harming metabolite HGA via secreted factors and collective peroxide scavenging.

Before environmental opportunistic pathogens can infect humans, they must first successfully grow and compete with other microbes in nature, often via secreted antimicrobials. We previously discovered that the bacterium Legionella pneumophila, the causative agent of Legionnaires' disease, can compete with other microbes via a secreted molecule called HGA. Curiously, L. pneumophila strains that produce HGA is not wholly immune to its toxicity, making it a mystery how these bacteria can withstand the "friendly fire" of potentially self-targeting antimicrobials during inter-bacterial battles. Here, we identify several strategies that allow the high-density bacterial populations that secrete HGA to tolerate its effects. Our study clarifies how HGA works. It also points to some explanations of why it is difficult to disinfect L. pneumophila from the built environment and prevent disease outbreaks.

On the evaluation of the antimicrobial effect of grape seed extract and cold atmospheric plasma on the dynamics of Listeria monocytogenes in novel multiphase 3D viscoelastic models

The demand for products that are minimally processed and produced in a sustainable way, without the use of chemical preservatives or antibiotics have increased over the last years. Novel non-thermal technologies such as cold atmospheric plasma (CAP) and natural antimicrobials such as grape seed extract (GSE) are attractive alternatives to conventional food decontamination methods as they can meet the above demands. The aim of this study was to investigate the microbial inactivation potential of GSE, CAP (in this case, a remote air plasma with an ozone-dominated RONS output) and their combination against L. monocytogenes on five different 3D in vitro models of varying rheological, structural, and biochemical composition. More specifically, we studied the microbial dynamics, as affected by 1 % (w/v) GSE, CAP or their combination, in three monophasic Xanthan Gum (XG) based 3D models of relatively low viscosity (1.5 %, 2.5 % and 5 % w/v XG) and in a biphasic XG/Whey Protein (WPI) and a triphasic XG/WPI/fat model. A significant microbial inactivation (comparable to liquid broth) was achieved in presence of GSE on the surface of all monophasic models regardless of their viscosity. In contrast, the GSE antimicrobial effect was diminished in the multiphasic systems, resulting to only a slight disturbance of the microbial growth. In contrast, CAP showed better antimicrobial potential on the surface of the complex multiphasic models as compared to the monophasic models. When combined, in a hurdle approach, GSE/CAP showed promising microbial inactivation potential in all our 3D models, but less microbial inactivation in the structurally and biochemically complex multiphasic models, with respect to the monophasic models. The level of inactivation also depended on the duration of the exposure to GSE. Our results contribute towards understanding the antimicrobial efficacy of GSE, CAP and their combination as affected by robustly controlled changes of rheological and structural properties and of the biochemical composition of the environment in which bacteria grow. Therefore, our results contribute to the development of sustainable food safety strategies.

Rapid In Situ Thermal Decontamination of Wearable Composite Textile Materials.

Pandemics stress supply lines and generate shortages of personal protective equipment (PPE), in part because most PPE is single-use and disposable, resulting in a need for constant replenishment to cope with high-volume usage. To better prepare for the next pandemic and to reduce waste associated with disposable PPE, we present a composite textile material capable of thermally decontaminating its surface via Joule heating. This material can achieve high surface temperatures (>100 °C) and inactivate viruses quickly (<5 s of heating), as evidenced experimentally with the surrogate virus HCoV-OC43 and in agreement with analytical modeling for both HCoV-OC43 and SARS-CoV-2. Furthermore, it does not require doffing because it remains relatively cool near the skin (<40 °C). The material can be easily integrated into clothing and provides a rapid, reusable, in situ decontamination method capable of reducing PPE waste and mitigating the risk of supply line disruptions in times of need.

Ochratoxin A: Overview of Prevention, Removal, and Detoxification Methods.

Ochratoxins are the secondary metabolites of Penicillium and Aspergillus, among which ochratoxin A (OTA) is the most toxic molecule. OTA is widely found in food and agricultural products. Due to its severe nephrotoxicity, immunotoxicity, neurotoxicity, and teratogenic mutagenesis, it is essential to develop effective, economical, and environmentally friendly methods for OTA decontamination and detoxification. This review mainly summarizes the application of technology in OTA prevention, removal, and detoxification from physical, chemical, and biological aspects, depending on the properties of OTA, and describes the advantages and disadvantages of each method from an objective perspective. Overall, biological methods have the greatest potential to degrade OTA. This review provides some ideas for searching for new strains and degrading enzymes.

Modeling and optimization of the self-embrittle corrosive bifunctional detergent for corrosive deep decontamination of stainless steel surface by RAFT one-pot method based on machine learning and response surface methodology

Nuclear facilities generate lots of contaminated stainless steel metallic material during maintenance and decommissioning. As a new radioactive decontamination method, the self-embrittle decontamination method has the advantage of less secondary contaminants and being able to operate machinery remotely. Adding a certain amount of corrosive components to the self-embrittle compound detergent can achieve the dual functions of self-embrittlement and corrosive decontamination. It was used to optimized the response surface methodology (RSM) and train and evaluate four different machine learning models by the recorded data set. The purpose of the analysis was to quantify the accuracy of the corrosion decontamination effect of RSM model and four types of machine learning model. The results exhibits that the long short-term memory neural network (LSTM) model performs well. The prepared detergent can achieve the average corrosion depth of 5.9454 μm on stainless steel, which can satisfy the corrosion decontamination of radioactively contaminated stainless steel surfaces.

Modern Methods of Decontamination of the Endodontic System

Modern Methods of Decontamination of the Endodontic System

The use of fibrous face masks as a barrier against infectious biological airborne particles

The Covid-19 pandemic has created a global health crisis which has affected the economic and social development. Infectious airborne particles are transmitted via direct contact or inhalation. In order to reduce the infection rates, face masks such as cloth, surgical and filtering facepiece respirator masks are being used as a nonpharmaceutical intervention. Face cloth masks are recommended for public use due the global shortages of traditional single use surgical and filtering facepiece respirators. Decontamination of masks for reuse is also being suggested in order to address the shortages and environmental pollution. Single use masks are disposed after one-time use and pose an environmental and health risk if not properly disposed. Incinerating masks releases toxic gases during combustion. Contaminated masks can be treated with heat, ultraviolet, chemicals and antimicrobial agents to deactivate microbial particles. The protection provided by masks can be compromised if the decontamination method damages the structural integrity, and heat and chemicals have been reported to cause this. When electrostatic charged masks are exposed to water and chemicals, they lose their electrostatic charge and as result their filtration efficiency decreases. Mask’s filtration efficiency from the highest to the lowest is in the order filtering facepiece respirator, surgical and cloth. Because masks act as a barrier and they cause breathability difficulty which is associated with the discomfort experience for the wearer. Breathability from the highest to the lowest is in the order cloth, surgical and filtering facepiece respirator.

Assessment of the barrier function of canine skin after repeated decontamination

Working canines often deploy into environments with unknown chemical and biological contaminants. Disaster canines may be deployed for lengthy periods and thus may experience longer periods of environmental exposure with greater possibility for contaminant contact. The skin functions as a protective barrier to prevent potential contaminants and pathogens from entering the system. To mitigate the effects of contaminant exposure to canine and handler, daily decontamination efforts are often required. However, little data exist on the effect of repeated decontamination to the canine skin. The objective of this study was to identify changes to the skin associated with a 14-day serial decontamination program. Labrador retrievers (n = 8) were decontaminated daily using a dish detergent solution (1:8, detergent:water). Skin measurements were collected weekly for pH, trans-epidermal water loss (TEWL), sebum, and moisture. Additionally, visual assessments were recorded for skin health, coat condition, and dander scores (back and body). Statistical tests were conducted with SAS (version 9.4) with measured data analyzed using a PROC GLM two-way ANOVA and visual assessments analyzed using the PROC FREQ Chi-square test. Significance was set at 5% for all tests. Repeated decontamination significantly increased TEWL (P < 0.0001) through day 16 with values returning to baseline by day 49. Sebum was also affected by repeated, daily decontamination efforts (P = 0.0387). However, higher sebum values are seen later in the study, on day 42, and may be associated with recovery. In contrast, moisture content (P = 0.3842) and pH (P = 0.7462) were unaffected by repeated decontamination. Interestingly, dander scores assessed on the back were worsened by repeated decontamination (P = 0.0222), but dander scores assessed across the whole body were unaffected (P = 0.1804). Coat shine and softness were unaffected by decontamination (P = 0.1156 and P = 0.3418, respectively). Overall coat condition remained unchanged as a result of repeated decontamination efforts (P = 0.9466). These data demonstrate negative impacts to the skin barrier associated with daily decontamination, which may increase the risk of inflammation and skin damage (Ananthapadmanabhan et al., 2004; Vidémont et al., 2012). Future work should include investigations into safer methods of decontamination to mitigate these risks.

Biofilm Removal from In Vitro Narrow Geometries Using Single and Dual Pulse Er:YAG Laser Photoacoustic Irrigation.

The disinfection and removal of biofilm from titanium dental implants remains a great challenge in oral medicine. Here we present results of novel photoacoustic irrigation laser modalities for biofilm removal in model geometries mimicking the peri-implant pocket. The efficacy of single pulse (Er:YAG-SSP) and dual pulse (Er:YAG-AutoSWEEPS) photoacoustic irrigation modalities were determined for Enterococcus faecalis biofilm decontamination from titanium surfaces in narrow cylindrical and square gap geometries. The density of bacteria as well as the number of live bacteria were determined prior and after different photoacoustic treatments. Both SSP and AutoSWEEPS photoacoustic irrigation techniques removed at least 92% of biofilm bacteria during the 10 s photoacoustic treatment. The effectiveness of cleaning was better in the narrow square gap geometry compared to the cylindrical geometry. The dual pulse Er:YAG-AutoSWEEPS photoacoustic irrigation showed better results compared to SSP modality. No chemical adjuvants were needed to boost the effectiveness of the photoacoustic irrigation in the saline solution. The results imply that photoacoustic irrigation is an efficient cleaning method for debridement and decontamination in narrow geometries and should be considered as a new therapeutic option for the treatment of peri-implant diseases.

Effectiveness of Ultra-High Irradiance Blue Light-Emitting Diodes in Inactivating Escherichia coli O157:H7 on Dry Stainless Steel and Cast-Iron Surfaces.

The use of blue light-emitting diodes (LEDs) is emerging as a promising dry decontamination method. In the present study, LEDs emitting ultra-high irradiance (UHI) density at 405 nm (842 mW/cm2) and 460 nm (615 mW/cm2) were used to deliver high-intensity photoinactivation treatments ranging from 221 to 1107 J/cm2. The efficacy of these treatments to inactivate E. coli O157:H7 dry cells was evaluated on clean and soiled stainless steel and cast-iron surfaces. On clean metal surfaces, the 405 and 460 nm LED treatment with a 221 J/cm2 dose resulted in E. coli reductions ranging from 2.0 to 4.1 log CFU/cm2. Increasing the treatment energy dose to 665 J/cm2 caused further significant reductions (>8 log CFU/cm2) in the E. coli population. LED treatments triggered a significant production of intracellular reactive oxygen species (ROS) in E. coli cells, as well as a significant temperature increase on metal surfaces. In the presence of organic matter, intracellular ROS generation in E. coli cells dropped significantly, and treatments with higher energy doses (>700 J/cm2) were required to uphold antimicrobial effectiveness. The mechanism of the bactericidal effect of UHI blue LED treatments is likely to be a combination of photothermal and photochemical effects. This study showed that LEDs emitting monochromatic blue light at UHI levels may serve as a viable and time-effective method for surface decontamination in dry food processing environments.

EFFICACY OF VINEGAR, THYME WATER AND vB_EcoM-P34 PHAGE IN INHIBITING Escherichia coli O157:H7 IN LETTUCE

The antibacterial activity of thyme water, apple vinegar, grape vinegar, and vB_EcoM-P34 phage against Escherichia coli O157:H7 ATCC 35150 and their potential to be utilized for decontamination on lettuce were examined in this study. Lettuce samples were treated with thyme water, apple or grape vinegar solutions (10, 25, 50%), vB_EcoM-P34 phage (about 108 PFU/mL) or tap water for 30 min after inoculation of lettuce with E. coli O157:H7 at the level of 5.66 log. Depending on the concentration, vinegars and thyme water reduced the bacterial count in lettuce by between 0.78 and 2.69 logs. The most effective reduction was achieved by treatment with vB_EcoM-P34 at 3.23 log. Bacteriophage was the most suitable method for decontamination, followed by grape vinegar, apple vinegar, and thyme water at 50%. However, high concentrations of vinegars and thyme water caused a sharp odor and a slight lightening in the color of the lettuce.

Microfiltration for effective microbiological decontamination of edible insects – Protein hydrolysis, aggregation and pH are critical for protein recovery

During the processing of insects for food and feed applications, thermal treatments are often used for decontamination purposes. However, these treatments denature proteins comprising their functional properties. Milder methods for microbiological decontamination can be used, such as microfiltration. Therefore, in this study dead-end microfiltration (0.2 µm polyethersulphone membrane) was tested for decontamination of soluble fractions of lesser mealworms and house crickets obtained at pH values of 3 and 8. The results showed that dead-end microfiltration was successful in the removal of microorganisms (total viable count), removing the need for thermal treatments for the permeates. Protein recovery in the permeate was relatively low (14–43 %). Lesser mealworms at pH 3 gave the highest protein recovery in the permeate (43 %), as explained by the activity of endogenous proteases producing soluble peptides during microfiltration. Confocal imaging showed that the efficiency of microfiltration was reduced by membrane fouling caused by protein aggregation. The presence of lipids in the pre-filtrate does not hamper the permeate protein recovery. In conclusion, dead-end microfiltration with a 0.2 µm membrane is successful in achieving microbial stability. A pH of 3 is recommended during the extraction process to obtain a higher protein recovery.