Current Decontamination Methods Research Articles

An innovative Fuller’s earth-based film-forming formulation for skin decontamination, through removal and entrapment of an organophosphorus compound, paraoxon-ethyl

Organophosphorus compounds (OPs), such as VX, pose a significant threat due to their neurotoxic and hazardous properties. Skin decontamination is essential to avoid irreversible effects. Fuller’s earth (FE), a phyllosilicate conventionally employed in powder form, has demonstrated decontamination capacity against OPs. The aim of this study was to develop a formulation that forms a film on the skin, with a significant OP removal capacity (>95 %) coupled with sequestration capabilities, favorable drying time and mechanical properties to allow for easy application and removal, particularly in emergency context. Various formulations were prepared using different concentrations of polyvinyl alcohol (PVA), FE and surfactants. Their removal and sequestration capacity was tested using paraoxon-ethyl (POX), a chemical that simulates the behavior of VX. Formulations with removal capacity levels surpassing 95 % were mechanically characterized and cell viability assays were performed on Normal Human Dermal Fibroblast (NHDF). The four most promising formulations were used to assess decontamination efficacy on pig ear skin explants. These formulations showed decontamination levels ranging from 84.4 ± 4.7 % to 96.5 ± 1.3 %, which is equivalent to current decontamination methods. These results suggest that this technology could be a novel and effective tool for skin decontamination following exposure to OPs.

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.

(Digital Presentation) Water Treatment through the Arc and Pulsed Spark Discharge

Water deterioration and depletion are accompanied by population growth and fast urbanization, posing major environmental problems. The prevalence of water-borne infections remains high, making it critical to discover effective ways of disinfecting water thoroughly. The main methods for inactivating a wide spectrum of harmful bacteria are chemical, physical, electrochemical, and radical. Conventional decontamination methods not only fail to completely disinfect water but also have several drawbacks, including the generation of disinfection byproducts; the complexity of disinfection reactor design; high energy consumption; and high running expenses. As a result, a versatile approach should be developed to overcome the limitations of current decontamination methods while also being efficient against a variety of diseases. Plasma-based water treatment has recently emerged as a possible alternative to traditional approaches. Plasma has proven to be more effective than conventional oxidants and disinfectants, both directly and indirectly. Plasma-related effects vary depending on the type of discharge, device settings, and process parameters. Electrical discharges are one of the most effective water treatment treatments. To this end, two plasma discharges, i.e., arc and pulsed spark discharge, are used for the treatment of synthetic contaminated water with microorganisms, which can be used for naturally contaminated surface water. Our results revealed that in comparison to arc discharge, pulse spark discharge produces more extreme acidic conditions by lowering the pH of water samples as well as a more reactive environment, which results in greater antibacterial efficacy. Furthermore, water samples treated with arc discharge had greater temperatures than water samples treated with pulse spark discharge, indicating that temperature was not a critical effector in the plasma-based sterilizing process.

Nano-Hydroxyapatite Airborne-Particle Abrasion System as an Alternative Surface Treatment Method on Intraorally Contaminated Titanium Discs.

The aim of this study was to test the nano-hydroxyapatite powder decontamination method on intraorally contaminated titanium discs and to compare this method with current decontamination methods in the treatment of peri-implantitis. Contaminated discs were assigned to six treatment groups (n = 10 each): titanium hand curette; ultrasonic scaler with a plastic tip (appropriate for titanium); ultrasonic scaler with a plastic tip (appropriate for titanium) + H2O2; short-term airflow system (nano-hydroxyapatite airborne-particle abrasion for 30 seconds); long-term airflow system (nano-hydroxyapatite airborne-particle abrasion for 120 seconds); Er:YAG laser (120 mJ/pulse at 10 Hz). There were also two control groups (n = 10 each): contaminated disc (negative control) and sterile disc (positive control). Scanning electron microscopy, energy-dispersive x-ray spectroscopy, and dynamic contact angle analysis were used to determine the most effective surface-treatment method. The highest percentage of carbon (C) atoms was observed in the negative control group, and the lowest percentage of C atoms was found in the long-term airflow group, followed by the short-term airflow, laser, ultrasonic + H2O2, ultrasonic, and mechanical groups. When the groups were examined for wettability, the lowest contact angle degree was observed in the long-term airflow, short-term airflow, and laser groups. Nano-hydroxyapatite and laser treatments for detoxifying and improving infected titanium surfaces may show the most suitable results for reosseointegration.

Radio-Frequency Processing for Inactivation of Salmonella enterica and Enterococcus faecium NRRL B-2354 in Black Peppercorn

Several Salmonella outbreaks linked to black pepper call for effective inactivation processes, because current decontamination methods result in quality deterioration. Radio-frequency (RF) heating provides a rapid heating rate and volumetric heating, resulting in a shorter come-up time. This allows for choosing a high-temperature and short-time combination to achieve the desired inactivation with minimal quality deterioration. The objectives of this study were to evaluate RF heating for inactivation of Salmonella enterica and Enterococcus faecium in black peppercorn and evaluate quality changes of RF-treated black peppercorn. Black peppercorns were inoculated with a five-strain cocktail of Salmonella or E. faecium to attain initial population levels of 6.8 and 7.3 log CFU/g, respectively, and were then adjusted to a moisture content of 12.7% (wet basis) and a water activity of 0.60 at room temperature. A stability test was performed to quantify the microbial reduction during inoculation and equilibration before RF heating inactivation. During RF heating, the cold spot was determined to be at the center on the top surface of the treated sample. In addition to inoculating the entire sample, an inoculated packed sample was placed at the cold spot of the tray. An RF heating time of 2.5 min provided a 5.31- and 5.26-log CFU/g reduction in the entire sample contained in the tray for Salmonella and E. faecium, respectively. Color parameters (L*, a*, b*), piperine content, total phenolics, scavenging activity, and most of the volatile compounds of 2.5-min RF-treated samples were not significantly different from those of the control samples. These data suggest that RF heating is a promising thermal inactivation treatment for Salmonella without significant quality deterioration, and E. faecium seems to be a suitable surrogate for Salmonella to validate the efficacy of RF heating of black peppercorn.

Decontamination of titanium implants using physical methods.

Current decontamination methods of titanium (Ti) implant present limited success in achieving predictable re-osseointegration. We hypothesized that even though these techniques could be useful in elimination of bacteria, they might be unsuccessful in removing organic contaminants and restoring the original surface composition. The aim of this study was to assess the effect of four decontamination methods on the surface chemistry and bacterial load of biofilm-contaminated implant surfaces in order to improve implant surface decontamination. The ability of clinically available methods such as metal and plastic curettes, Ti brushes and Er: YAG laser to decontaminate Ti implant surfaces was assessed. Surface morphology, chemical composition and properties of machined Ti discs (Ø 5.0 and 1.0mm thick) were analysed before and after oral biofilm contamination using scanning electron microscope and X-ray photoelectron spectroscopy. The presence and viability of bacteria were evaluated with live-dead assays. Biofilm contamination created an organic layer rich in hydrocarbons and bacteria that covered entirely the Ti surfaces. This organic layer has tightly adhered to Ti surfaces and could not be completely removed with any of the methods assessed. Ti brushes achieved greater elimination of organic contaminants and bacteria than curettes and Er: YAG laser; however, none of them was able to restore the original surface chemistry. Alternatively, Er: YAG laser-treated surfaces showed the lowest live-to-dead bacterial ratio. Ti brushes were more effective than curettes (metal or plastic) and Er: YAG laser in decontaminating Ti implant surfaces, although none of these techniques was able to completely eliminate surface contamination. Er: YAG laser was more effective than curettes and Ti brushes in killing the biofilm bacteria.

Proposed human stratum corneum water domain in chemical absorption.

Compounds with varying physical and chemical properties may have different affinities to the stratum corneum (SC) and/or its intercellular lipids, keratin protein, and possible water domains. To better understand the mechanism of percutaneous absorption, we utilized 21 carbon-14 labeled chemicals, with wide hydrophilicity (log P = -0.05 to 6.17), and quantified their absorption/adsorption properties for a short incubation time (15 min) with regards to intact SC membrane, delipidized SC membrane and SC lipid. A facile method was developed for SC/lipid absorption, providing a more equivalent procedure and comparable data. SC lipid absorption of chemical solutes positively correlated with the octanol/water partition coefficient (log P). Differences between the percent dose of chemical absorption to intact SC and the total percent dose contributed by the protein and lipid domains suggest the possibility and significance of a water domain. Absorption rate experiments showed a longer lag time for intact SC than for delipidized SC or SC lipid, suggesting that the water domain may delay chemical binding to protein and lipid domains, and may be a factor in the resistance of many chemicals to current decontamination methods. Copyright © 2015 John Wiley & Sons, Ltd.

An Efficient Multistrategy DNA Decontamination Procedure of PCR Reagents for Hypersensitive PCR Applications

BackgroundPCR amplification of minute quantities of degraded DNA for ancient DNA research, forensic analyses, wildlife studies and ultrasensitive diagnostics is often hampered by contamination problems. The extent of these problems is inversely related to DNA concentration and target fragment size and concern (i) sample contamination, (ii) laboratory surface contamination, (iii) carry-over contamination, and (iv) contamination of reagents.Methodology/Principal FindingsHere we performed a quantitative evaluation of current decontamination methods for these last three sources of contamination, and developed a new procedure to eliminate contaminating DNA contained in PCR reagents. We observed that most current decontamination methods are either not efficient enough to degrade short contaminating DNA molecules, rendered inefficient by the reagents themselves, or interfere with the PCR when used at doses high enough to eliminate these molecules. We also show that efficient reagent decontamination can be achieved by using a combination of treatments adapted to different reagent categories. Our procedure involves γ- and UV-irradiation and treatment with a mutant recombinant heat-labile double-strand specific DNase from the Antarctic shrimp Pandalus borealis. Optimal performance of these treatments is achieved in narrow experimental conditions that have been precisely analyzed and defined herein.Conclusions/SignificanceThere is not a single decontamination method valid for all possible contamination sources occurring in PCR reagents and in the molecular biology laboratory and most common decontamination methods are not efficient enough to decontaminate short DNA fragments of low concentration. We developed a versatile multistrategy decontamination procedure for PCR reagents. We demonstrate that this procedure allows efficient reagent decontamination while preserving the efficiency of PCR amplification of minute quantities of DNA.

Application of epifluorescence scanning for monitoring the efficacy of protein removal by RF gas–plasma decontamination

The development of methods for measuring the efficiency of gas–plasma decontamination has lagged far behind application. An approach to measuring the efficiency of protein removal from solid surfaces using fluorescein-labelled bovine serum albumin and epifluorescence scanning (EFSCAN) is described. A method for fluorescently labelling proteins, which are adsorbed and denatured on metal surfaces, has been developed. Both approaches have been used to evaluate the efficiency of radio frequency (RF) gas–plasma decontamination protocols. Examples with ‘real’ surgical instruments demonstrate that an argon–oxygen RF gas–plasma treatment can routinely reduce the protein load by about three orders of magnitude beyond that achieved by current decontamination methods.