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Inactivation of duck hepatitis B virus by a hydrogen peroxide gas plasma sterilization system: Laboratory and 'in use' testing
Abstract
Human hepatitis B virus (HBV) is an important cause of nosocomial infections and can be transmitted by contaminated instruments. However, tests of the efficacy of sterilization of materials and equipment contaminated by HBV are difficult to perform because the virus cannot be cultured in the laboratory. In this study, we aimed to evaluate the capability of a low temperature, hydrogen peroxide gas plasma sterilizer (Sterrad, Advanced Sterilization Products, Irvine California,) to inactivate duck hepatitis B virus (DHBV). In laboratory efficacy studies using DHBV dried on to glass filter carriers and exposed to one-half of the hydrogen peroxide gas plasma sterilization process, there was a 10(7) or greater decrease in the viral titer, with no infectivity detected on the carriers after treatment. In-use studies were performed using a laparoscope that was experimentally contaminated with DHBV to mimic the possible transmission of infection between successive patients. Following exposure to the hydrogen peroxide gas plasma sterilization process no transmission of DHBV infection from the laparoscope occurred despite obvious visual soiling with blood (N = 8) while the transmission rate for the unprocessed laparoscope (positive control) was 100% (26/26), and that for instruments after a water wash was 63% (7/11). In conclusion the hydrogen gas plasma sterilization process completely inactivates DHBV a representative of the hepadna group of viruses.
... It has been shown to be a very efficient technique to sterilize surgical equipment. 16,[21][22][23] However, to the best of our knowledge, there are no data on the effect of different sterilization techniques on foam. The foam and all the components of the single-access port system used in this study are sterilized with ethylene oxide by the manufacturer, although the ethylene oxide's effect on the foam is likely proprietary information. ...
... 4 Studies have evaluated the efficacy of steam autoclave, ethylene oxide, and hydrogen peroxide gas plasma sterilization on bacteria, fungus, virus, and prions with or without blood contamination. 6,21,22,25 SUDs were effectively sterilized with ethylene oxide when challenged with bacterial spores contaminated with blood. 6 Hydrogen peroxide gas plasma was similarly shown to be virucidal and to inactivate prions in laboratory settings. ...
... 6 Hydrogen peroxide gas plasma was similarly shown to be virucidal and to inactivate prions in laboratory settings. 21,22,25 The enzymatic cleaner Endozime Bio-Clean (RUHOF) was used in this study for decontamination and cleansing. This enzymatic cleaner is a neutral pH enzymatic detergent designed to target insoluble polysaccharides, allowing for the elimination of all bioburden and biofilm on medical devices. ...
Objective:
To determine the efficacy of repeated decontamination and sterilization of a disposable port intended for 1-time use during single-incision laparoscopy.
Study design:
Experimental; prospective, controlled design.
Methods:
Six single-access ports used 4 times and 6 single-access ports used 8 times to perform various clean, minimally invasive surgeries were evaluated. Ports were decontaminated in an enzymatic cleaner (dilution, 3:100) and cleaned with a scrub brush for 5 minutes. The ports were then sterilized with hydrogen peroxide vapor for 50 minutes using a standard protocol at a concentration of 6 mg/L, followed by a vapor diffusion phase. Samples taken from the foam, insufflating tubing, and rigid cannula portion of each port were collected with aseptic technique for aerobic-anaerobic cultures. Port material samples were set up on a tryptic soy agar plate with 5% sheep blood, a MacConkey agar plate, and a Columbia agar plate with 5% sheep blood (CAP). Anaerobic isolate cultures were set up on Centers for Disease Control and Prevention (CDC) blood agar and CAP.
Results:
None of the ports used 4 times had positive bacteriologic culture. Two of the ports used 8 times had a light growth of bacteria. The first positive sample cultured Staphylococcus spp. and Micrococcus spp. The second positive sample cultured Staphylococcus epidermidis. The positive cultures were obtained from the foam component in an enriched broth.
Conclusion:
Single-incision ports could be used safely 4 times and pose a low risk of infection to the patient under conditions of this study.
... These techniques are now achieving the required sterilization standards, and practical application is close to becoming realized. However, there remain key areas requiring further investigation such as; the speed of the sterilization process [18][19][20], disinfection of abiotic materials that have pathogenicity [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38], and understanding the compatibility of plasmas with different materials [39]. This work is necessary for the continued development of this very promising area. ...
... Currently, several commercial gas plasma sterilization instruments are available. Inactivation of prions [32], human immunodeficiency virus (HIV) [33], hepatitis A virus [33], respiratory syncytial virus [33], vaccinia virus [33], herpes simplex virus [33], poliovirus [33], duck hepatitis B virus [34], and bacterial spores [35][36][37] have been shown using these Table 3. Resistance of pathogens and inactivation by gas plasma. * More highly resistant pathogens are listed in the upper rows. ...
Plasma sterilization methods have been studied for over 20 years in Japan and around the world, and are currently being developed for practical application. However, persisting challenges, such as the speed of the sterilization treatment, treatment of pathogenic proteins on medical equipment, and the compatibility of plasma with materials of medical equipments, currently limit the widespread application of the techniques. This paper introduces research into plasma sterilization for practical use, which is currently being carried out.
... Thus, DHBV can be propagated in vivo in ducklings or in vitro in primary duck embryonic hepatocytes to assess viral infectivity [56,[60][61][62] . Several authors have reported using in vivo DHBV assays [54,55,[63][64][65] . To estimate DHBV infectivity, the diluted viral suspensions exposed to the biocides are injected intraperitoneally or intravenously into naïve ducklings not infected with DHBV. ...
... Australia 1 Vickery et al [64] Hydrogen peroxide 2000 ...
The hepatitis B virus (HBV) is considered to be a major public health problem worldwide, and a significant number of reports on nosocomial outbreaks of HBV infections have been reported. Prevention of indirect HBV transmission by contaminated objects is only possible through the use of infection-control principles, including the use of chemical biocides, which are proven to render the virus non-infectious. The virucidal activity of biocides against HBV cannot be predicted; therefore, validation of the virucidal action of disinfectants against HBV is essential. However, feasible HBV infectivity assays have not yet been established. Thus, surrogate models have been proposed for testing the efficacy of biocides against HBV. Most of these assays do not correlate with HBV infectivity. Currently, the most promising and feasible assay is the use of the taxonomically related duck hepatitis B virus (DHBV), which belongs to the same Hepadnaviridae virus family. This paper reviews the application of DHBV, which can be propagated in vitro in primary duck embryonic hepatocytes, for the testing of biocides and describes why this model can be used as reliable method to evaluate disinfectants for efficacy against HBV. The susceptibility levels of important biocides, which are often used as ingredients for commercially available disinfectants, are also described.
... Several studies have evaluated the relative microbicidal efficacy of these low-temperature sterilization technologies (Table 14). These studies have either tested the activity of a sterilization process against specific microorganisms 727,742,743 , evaluated the microbicidal activity of a singular technology 563,692,714,717,718,725,726,730,738,744 or evaluated the comparative effectiveness of several sterilization technologies 229,327,354,566,693,694,719,727,742,743,745,746 . Several test methodologies use stainless steel or porcelain carriers that are inoculated with a test organism. ...
... Several studies have evaluated the relative microbicidal efficacy of these low-temperature sterilization technologies (Table 14). These studies have either tested the activity of a sterilization process against specific microorganisms 727,742,743 , evaluated the microbicidal activity of a singular technology 563,692,714,717,718,725,726,730,738,744 or evaluated the comparative effectiveness of several sterilization technologies 229,327,354,566,693,694,719,727,742,743,745,746 . Several test methodologies use stainless steel or porcelain carriers that are inoculated with a test organism. ...
... Further studies have revealed that one of the human hepatitis B viruses (HBV) could be transmitted by contaminated apparatuses, which is considered a primary source of nosocomial infections. As it is difficult to cultivate in the laboratory, HBV decontamination is challenging to execute; thus, Vickery et al [118] used commercially available hydrogen peroxide gas plasma sterilizer on experimental surfaces contaminated with duck hepatitis B virus (DHBV) to mimic the likely transmission of contamination in sequential patients to inactivate DHBV. Following treatment with this plasma, sterilization of the instruments after a water wash was more than 60%. ...
Background
Outbreaks of airborne viral infections, such as COVID-19, can cause panic regarding other severe respiratory syndrome diseases that may develop and affect public health. It is therefore necessary to develop control methods that offer protection against such viruses.
Aim
of Review: To identify a feasible solution for virus deactivation, we critically reviewed methods of generating reactive oxygen species (ROS), which attack a wide range of molecular targets to induce antiviral activity, accounting for their flexibility in facilitating host defense mechanisms against a comprehensive range of pathogens. Recently, the role of ROS in microbial decontamination has been critically investigated as a major topic in infectious diseases. ROS can eradicate pathogens directly by inducing oxidative stress or indirectly by promoting pathogen removal through numerous non-oxidative mechanisms, including autophagy, T-cell responses, and pattern recognition receptor signaling.
Key scientific concepts of review: In this article, we reviewed possible methods for the in vitro generation of ROS with antiviral activity. Furthermore, we discuss, in detail, the novel and environmentally friendly cold plasma delivery system in the destruction of viruses. This review highlights the potential of ROS as therapeutic mediators to modernize current techniques and improve on the efficiency of inactivating SARS-CoV2 and other viruses.
... These technical considerations, added to organizational, economic, and legal requirements, related to the need of qualifying and certifying all reprocessing procedures, suggest to consider the introduction of this practice in hospitals and health care structures with a significant workload. A useful recommendation to minimize endotoxin contamination is to process, package and promptly sterilize the item to reuse in order to limit the time of bacterial contamination and growth (Kundsin and Walter, 1980 Vickery, 1999). The characterization of the sterilization process, based on an effective sequence of chemical and physical reactions including ionised species, free radicals, and UV radiation, may also suggest a potentiality for endotoxins reduction as argued by some authors (Lerouge et al., 2001;Moisan et al., 2001). ...
Modern medicine makes large use of minimally invasive technology based on single use devices (SUDs), but the increasing number of interventions and the consequent economic load on health system, drove many countries to adopt a reprocessing policy.
From literature analysis there are conflicting results regarding the safety and effectiveness of SUDs reuse. Nowadays, one of the few areas where such a reuse seems suitable both for safeness and cost effectiveness is interventional cardiology.
Considering that SUDs reprocessing represents the introduction of a new health technology, a multidisciplinary approach based on the Heath Technology Assessment (HTA) method is required, where stringent criteria of effectiveness, safety and suitability must be satisfied.
Important HTA reports on SUDs re-use, recently delivered by international public agencies, pointed out a substantive gap in knowledge regarding safety and effectiveness of this policy. At the present time there are no sufficient studies on re-use feasibility, nor studies on validation of devices reprocessing. This work aimed to bridge this gap by producing original experimental evidences.
For a safe and efficient device reuse, regeneration protocol should be designed to completely recover all hygienic and functional requirements provided by new devices. Available literature underlines the need to determine the correct cleaning, disinfection, and sterilization techniques and the relevant quality control. To define the organizational procedures and to place responsibilities in the use of reprocessed materials clear guidelines should be drafted.
The study aimed to define the fundamental steps for the assessment of a reprocessing procedure on interventional cardiac catheters.
Following HTA methodologies, the priority-setting definition underlined the need for technical, ethical, legal, and economic investigations. The experimental techniques applied in this work supply parameters for an adequate assessment of quality and safety of new and reprocessed devices. Device technical data and legal, bioethical, and economic issues are than integrated just in order to define the applicability and suitability of the SUDs reprocessing in interventional cardiology. Experimental data by conducing laboratory analyses on more than 650 devices including EP and PTCA catheters of the major worldwide manufacturers were produced. More than 2000 technical and biological tests were conducted on devices reprocessed up to 14 and 4 times for electrophysiology and angioplasty catheters respectively.
Several experimental analyses elicited critical outcomes such as material modifications, functionality, residual bioburden, sterility and pyrogenic load after reprocessing. Furthermore the study faces juridical item by a comparative analysis and proposes a cost analysis model for saving evaluation.
This work was carried out in laboratory settings and therefore does not provide outcomes directly related to patients. In order to have a definitive answer about SUDs reuse feasibility in clinical settings, monitoring SUDs reuse efficacy and safeness on patients is mandatory, and multicentric clinical studies should be designed to evidence any causal link between reprocessing and adverse outcomes.
However, ethical constrains are present in using patients for clinical studies designed to determine the risk associated with SUDs reuse. This study addresses the procedural conditions to minimize the risk of failure and cross-infection associated with the reprocessed device, thus representing a propaedeutic approach for any following clinical trials.
Finally, according to the main worldwide investigations, SUDs reprocessing needs for the implementation of strict regulatory environment to guarantee patients safety and enable monitoring of reuse practices.
As a main result of the study, a list of recommendations was drafted.
The reprocessing protocol should be conceived according to material properties and design of the specific device model.
The efficacy of any reprocessing protocol should be verified by safe, reproducible, and regularly updated investigation techniques able to provide deep analyses of materials, functionality, and biological aspects.
Essential quality tests should be performed on every reprocessing cycle and on every single device.
Maximum number of reprocessing cycles should be specified according to devices features, use conditions, and reprocessing protocol.
Pre-sterilization processing conditions and techniques are critical for sterilization success.
Decontamination, cleaning, and washing procedures, together with sterilization techniques could induce chemical, physical and morphological modifications on the treated surfaces and potential toxicity of the sterilized device.
Complexity of reprocessing protocols, organizational issue, economic, and legal requirements addressed to qualifying and certifying all steps of the reprocessing procedure discourage “in house” reprocessing.
... Low-temperature (LT) plasma is currently used for modification of various surfaces in industry applications, mechanical engineering, and the chemical industry, but its uses for various biological and medical applications are also being intensively studied. Application of LT plasma treatment has been described for killing pathogens and their spores 1,2 ; sterilization or inactivation of several bacteria strains, 3,4 yeast, 5,6 and viruses 7 ; inhibition or deactivation of fungi [8][9][10] ; sterilization of surgical tools 11 and foodstuffs 12 ; and destruction of biological toxins. 13 A successful plasma application in practical medicine to treat inflammatory eye and skin diseases and to stimulate regeneration processes has been also described. ...
Surface treatment by low-temperature plasma has a great potential in a wide range of applications in many industries and research fields, such as material engineering, automobile industry, ecology, medicine, and agriculture. The application of plasma treatments is relatively new and not very common in agriculture. Protecting cereal seeds against some fungal diseases is one of the plasma applications in agriculture. We tested the possibility of decreased mycotoxin concentration by low pressure and atmospheric pressure plasmas. In addition, we investigated the effects of plasma treatment on nutritive values of the seeds because of their usage as domestic animal feed. The influence on seed germination was also studied and are also reported here.
... Currently, there is only one commercial gas plasma sterilizer, STERRAD ® (Johnson & Johnson K.K). Inactivation of HIV [34], hepatitis A virus [34], respiratory syncytial virus (RSV) [34], vaccinia virus [34], HSV [34], poliovirus [34], and duck hepatitis B virus [53] by this machine has been reported. However, the mechanisms of action in STERRAD ® mainly seem to be due to the effect of vaporized hydrogen peroxide, not gas plasma. ...
Viruses are infectious particles composed of nucleic acids and proteins that depend on cells for energy. Viruses invade cells where they proliferate, resulting in disease. Sterilization, disinfection, and antisepsis are important for preventing diseases derived from pathogens such as viruses. The disinfectants used for viruses are mostly chemicals including alcohols like ethanol and isopropanol. Alcohols are effective against enveloped viruses such as human immunodeficiency virus (HIV) and influenza virus but not small non-enveloped viruses such as parvovirus and poliovirus. To develop methods of sterilization, confirmation of results using appropriate samples is necessary. Towards this goal, several physical methods have recently been developed to facilitate sterilization; including the use of pulsed light, supercritical fluids, pulsed electric fields, and gas plasma. Although most of these methods have not been widely adopted, further increases in reliability, convenience, and suitability should contribute to the spread of their applicability. In this review, we describe viruses, conventional means of disinfection, trends in the development of new methods of sterilization and potential applications of these methods.
... Indeed, disinfection efficiency of alcohol against influenza virus varies depending on the presence of coexisting organic material [19]. Most regulatory authorities require sterilant efficacy testing to be conducted in the presence of 5% soil [20]. Influenza virus is usually encountered in the nasal fluid of patients and allantoic fluid of eggs. ...
We have recently treated with N2 gas plasma and achieved inactivation of bacteria. However, the effect of N2 gas plasma on viruses remains unclear. With the aim of developing this technique, we analyzed the virucidal effect of N2 gas plasma on influenza virus and its influence on the viral components. We treated influenza virus particles with inert N2 gas plasma (1.5 kpps; kilo pulses per second) produced by a short high-voltage pulse generated from a static induction thyristor power supply. A bioassay using chicken embryonated eggs demonstrated that N2 gas plasma inactivated influenza virus in allantoic fluid within 5 min. Immunochromatography, enzyme-linked immunosorbent assay, and Coomassie brilliant blue staining showed that N2 gas plasma treatment of influenza A and B viruses in nasal aspirates and allantoic fluids as well as purified influenza A and B viruses induced degradation of viral proteins including nucleoprotein. Analysis using the polymerase chain reaction suggested that N2 gas plasma treatment induced changes in the viral RNA genome. Scanning electron microscopy analysis showed that aggregation and fusion of influenza viruses were induced by N2 gas plasma treatment. We believe these biochemical changes may contribute to the inactivation of influenza viruses by N2 gas plasma.
... H 2 O 2 is used for tissue sterilization to inactivate and eliminate a broad spectrum of micro-organisms such as yeasts, fungi and spores. It is highly efficient against a multitude of viruses, such as HIV-1, HAV, RSV, vaccinaand herpes-simplex virus type I (Vickery et al., 1999). Applied chaotropic salt and hydrogen peroxide solutions destroy most of the contained proteins of cartilage hydrolytically (Hattori et al., 1999). ...
One key point in the development of new bioimplant matrices for the reconstruction and replacement of cartilage defects is to provide an adequate microenvironment to ensure chondrocyte migration and de novo synthesis of cartilage-specific extracellular matrix (ECM). A recently developed decellularization and sterilization process maintains the three-dimensional (3D) collagen structure of native septal cartilage while increasing matrix porosity, which is considered to be crucial for cartilage tissue engineering. Human primary nasal septal chondrocytes were amplified in monolayer culture and 3D-cultured on processed porcine nasal septal cartilage scaffolds. The influence of chondrogenic growth factors on neosynthesis of ECM proteins was examined at the protein and gene expression levels. Seeding experiments demonstrated that processed xenogenic cartilage matrices provide excellent environmental properties for human nasal septal chondrocytes with respect to cell adhesion, migration into the matrix and neosynthesis of cartilage-specific ECM proteins, such as collagen type II and aggrecan. Matrix biomechanical stability indicated that the constructs retrieve full stability and function during 3D culture for up to 42 days, proportional to collagen type II and GAG production. Thus, processed xenogenic cartilage offers a suitable environment for human nasal chondrocytes and has promising potential for cartilage tissue engineering in the head and neck region. Copyright © 2012 John Wiley & Sons, Ltd.
... H 2 O 2 is used for tissue sterilization to inactivate and eliminate a broad spectrum of microorganisms like yeasts, fungi, and spores. It provides a high efficiency against a multitude of viruses like HIV-1, HAV, RSV, vaccinia, and herpes simplex virus type I. 30 The specific problem underlying this study was to provide a method that excludes the risk of infection and disease transmission and guarantees exhaustive decellularization for elimination of antigenicity and avoidance of immunoreactions. 31,32 On the other hand, processing of the cartilage tissue should not affect biomechanical integrity of cartilage transplant matrix, matrix recellularization capability, or chondroconductive properties. ...
Damage of cartilage structures in the head and neck region as well as in orthopedic sites are frequently caused by trauma, tumor resection, or congenital defects. Despite a high demand in many clinical fields, until today, no adequate cartilage replacement matrix is available for these fields of application. Materials that are clinically applied for joint cartilage repair still need optimization due to difficult intraoperative handling and risk of early mechanical damage. We have developed and applied a novel chemical process to completely decellularize and sterilize human and porcine cartilage tissues (meniscus cartilage and nasal septum) to generate a new type of bioimplant matrix. To characterize this matrix and to determine the effect of the decellularization process, the content of denatured collagen (w(D)) and the content of glycosaminoglycans (GAGs) (w(G)) were determined. Possible cytotoxic effects and cellular compatibility of the matrix in vitro have been examined by seeding processed cartilage biomatrices with human primary chondrocytes as well as murine fibroblasts (L929). Vitality and state of metabolism of cells were measured using MTS assays. Both cell types adhered to scaffold surfaces and proliferated. No areas of growth inhibition or cytotoxic effects were detected. New synthesis of cartilage-specific extracellular matrix was observed. By histological staining, electron microscopy, and μCT analysis, an increase of matrix porosity, complete cell elimination, and high GAG removal were demonstrated. Being from natural-origin, processed xenogenic and allogeneic cartilage biomatrices are highly versatile with regard to shape, size, and biomechanics, making them promising candidates for various biomedical applications.
... Vickery et al 90 have shown that the Sterrad system, which is based on a high concentration of vaporized hydrogen peroxide, was highly effective in inactivating DHBV, even in the presence of blood as a soil load. Formulations that are based on stabilized hydrogen peroxide 91 have not been tested against HBV but would be expected to work against it on the basis of their activity against tougher organisms, such as mycobacteria and nonenveloped viruses. ...
Hepatitis B virus (HBV) and hepatitis C virus (HCV) are the most prevalent bloodborne pathogens. Infections caused by these organisms can become chronic and may lead to liver cirrhosis and carcinoma. Limited chemotherapy is now available, but only HBV can be prevented through vaccination. Both viruses are enveloped and relatively sensitive to many physical and chemical agents; their ability to survive in the environment may not be as high as often believed. As a result, their spread occurs mainly through direct parenteral or percutaneous exposure to tainted body fluids and tissues. Careful screening of and avoiding contact with such materials remain the most effective means of protection. Nevertheless, the indirect spread of these viruses, although much less common, can occur when objects that are freshly contaminated with tainted blood enter the body or contact damaged skin. Germicidal chemicals are important in the prevention of HBV and HCV spread through shared injection devices, sharps used in personal services (such as tattooing and body piercing), and heat-sensitive medical/dental devices (such as flexible endoscopes) and in the cleanup of blood spills. Microbicides in vaginal gels may also interrupt their transmission. General-purpose environmental disinfection is unlikely to play a significant role in the prevention of the transmission of these viruses. Testing of low-level disinfectants and label claims for such products against HBV and HCV should be discouraged. Both viruses remain difficult to work with in the laboratory, but closely related animal viruses (such as the duck HBV) and the bovine viral diarrhea virus show considerable promise as surrogates for HBV and HCV, respectively. Although progress in the culturing of HBV and HCV is still underway, critical issues on virus survival and inactivation should be addressed with the use of these surrogates.
... 12. Classical survival curve (B) and three other commonly observed non-exponential survival curves (A, C, and D) designated as convex, sigmoid and concave curves, respectively, resulting from thermal inactivation (after Moats, 1971after Moats, ). al., 1996 Borneff-Lipp et al., 1997; Vassal et al., 1998; Vickery et al., 1999). ...
Utilizing an ionized gas (plasma) to achieve sterilization is an alternative to conventional sterilization means as far as sterilization of heat-sensitive materials and innocuity of sterilizing agents are concerned. The literature on plasma sterilization is reviewed. A major issue of plasma sterilization is the respective roles of UV photons and reactive species such as atomic and radicals. Insight into this matter is obtained by analyzing the survival curves of microorganisms. In contrast to classical sterilization where such plots show a unique straight line, plasma sterilization yields survival diagrams with two or three different linear segments. Three basic mechanisms are involved in the plasma inactivation of microorganisms: (A) direct destruction by UV irradiation of the genetic material of microorganisms; (B) erosion of the microorganisms atom by atom, through intrinsic photodesorption by UV irradiation to form volatile compounds combining atoms intrinsic to the microorganisms; (C) erosion of the microorganisms, atom by atom, through etching to form volatile compounds as a result of slow combustion using oxygen atoms or radicals emanating from the plasma. In some cases, etching is further activated by UV photons, increasing the elimination rate of microorganisms. These mechanisms make plasma sterilization totally different from classical sterilization techniques and suggest its use to inactivate nonconventional infectious agents such as the abnormal prions.
... With the DHBV model it has been possible to study the capability of a hydrogen peroxide gas plasma sterilizer. 9 By assessing the efficacy of two quaternary ammonium chloride disinfectants with a PCR for DNA detection, concentrations of 1200 and 1800 ppm were found to be effective against DHBV. 10 Later on, a quantitative PCR was developed based on SyBr green dye. 11 The DHBV model clearly demonstrated the importance of cleaning angioscopes before disinfection and sterilisation. ...
Hand disinfection is an important measure to prevent transmission of norovirus (formerly called Norwalk-like viruses) from hands or environmental surfaces to other objects. Therefore, three types of alcohol (ethanol, 1- and 2-propanol) were examined for their virus-inactivating properties against feline calicivirus (FCV) as a surrogate for norovirus. Tests were performed as quantitative suspension assays or as in vivo experiments with artificially contaminated fingertips. The in vitro experiments showed that 1-propanol was more effective than ethanol and 2-propanol for the inactivation of FCV: in tests with the 50 and 70% solutions of the different alcohols, a 10(4)-fold reduction was observed with 1-propanol after 30 s, whereas the other alcohols were effective only after 3 min contact time. The greatest efficacy did not occur at the highest concentrations (80%). The following concentrations (extrapolated data) showed the greatest virus-inactivating properties in the suspension test: ethanol 67%, 2-propanol 58% (exposure times of 1 min) and 1-propanol 60% (exposure time of 30 s). The results from fingertips experiments with 70 and 90% solutions and an application time of 30 s confirmed these findings: the 70% alcoholic solutions were more effective than the 90% solutions. In contrast to the suspension tests, 70% ethanol showed the greatest efficacy in vivo with a log(10) reduction factor (RF) of 3.78 compared with 70% 1-propanol (RF 3.58), 70% 2-propanol (RF 2.15) and hard water (RF 1.23). Ethanol and 1-propanol-based solutions with a high alcohol content thus appear most effective.
... Because of the novel and almost random nature of both parameters (pure oxygen and oxygen–hydrogen peroxide gas mixture), and the results obtained in this study, further investigation is required to confirm the results for the gas mixture. The Sterrad ® sterilization system has been used in a similar study (Vickery et al., 1999). In this equipment, hydrogen peroxide is effective since it is the main active agent and has a diffusion time of 50 min after injection of an 18 mL volume of the gas, at a concentration of 59% followed by 15 min of plasma at 400 W. In this case, it was not the hydrogen peroxide plasma but the precursor gas that was responsible for the death of the microbes. ...
Plasma is an innovative sterilization method characterized by a low toxicity to operators and patients, and also by its operation at temperatures close to room temperatures. The use of different parameters for this method of sterilization and the corresponding results were analyzed in this study. A low-pressure inductive discharge was used to study the plasma sterilization processes. Oxygen and a mixture of oxygen and hydrogen peroxide were used as plasma source gases. The efficacy of the processes using different combinations of parameters such as plasma-generation method, type of gas, pressure, gas flow rate, temperature, power, and exposure time was evaluated. Two phases were developed for the processes, one using pure oxygen and the other a mixture of gases. Bacillus subtilis var. niger ATCC 9372 (Bacillus atrophaeus) spores inoculated on glass coverslips were used as biological indicators to evaluate the efficacy of the processes. All cycles were carried out in triplicate for different sublethal exposure times to calculate the D value by the enumeration method. The pour-plate technique was used to quantify the spores. D values of between 8 and 3 min were obtained. Best results were achieved at high power levels (350 and 400 W) using pure oxygen, showing that plasma sterilization is a promising alternative to other sterilization methods.
Pathogenic viruses cause many human, animal, and plant diseases that are associated with substantial morbidity, mortality and socio-economic impact. Although effective strategies for combatting virus transmission and associated disease are available, global outbreaks of viral pathogens such as the virus responsible for the COVID-19 pandemic demonstrate that there is still a critical need for new approaches that can be used to interrupt the chain of viral infection and mitigate virus-associated pathogenesis. Recent studies point to non-thermal plasma (NTP), a partly ionized gas comprised of a complex mixture of reactive oxygen and nitrogen species along with physical effectors, as the potential foundation for new antiviral approaches. A more thorough understanding of the antiviral properties and safety of NTP has stimulated explorations of NTP as the basis for treatments of viral diseases. The recently described immunomodulatory properties of NTP are also being evaluated for potential use in immunotherapies of viral diseases as well as in antiviral vaccination strategies. In this review, we present the current state-of-the-art in addition to compelling arguments that NTP merits further exploration for use in the prevention and management of viral infections and associated diseases.
The outbreak of the novel coronavirus disease, COVID-19 turned into a global pandemic in March 2020. During these unprecedented times, there is an increased demand in medical and personal protective equipment (PPE). Since the supplies may take a long time to meet the global demand, reusing PPEs will help health care workers in their response to the COVID-19 pandemic. To ensure the safety and well-being of the medical first responders, PPE needs to be sterilized before reuse. In this review, we examine various sterilization techniques that can be used to sterilize PPEs and point out its limitations. The objective is to provide a foundation of knowledge incorporating different sterilization techniques that allow hospitals and clinics to pick the most suitable technique for sterilization of a particular PPE.
One of the most important aspects of infection control is the interruption of transmission of infectious organisms to and from patients within the hospital environment. Of particular concern are the blood-borne viruses HIV, hepatitis B virus (HBV) and hepatitis C virus (HCV). Disinfectants play an important role in infection control, but their virucidal efficacy is difficult to measure in vitro because of the high susceptibility of tissue culture systems to damage by chemical agents and the relatively low titres which are achieved in growing many important viruses. Additionally, HBV is almost uncultivable in vitro and fails to infect more common laboratory animals. Therefore, the duck model of HBV infection has been used for testing disinfectant action against HBV.
Public awareness of the role of microorganisms in infection and spoilage and the role of the media in highlighting poor hygiene and the failure of healthcare settings in preventing hospital-acquired infections, have fuelled the use of products containing one or several microbicides in the healthcare environment but also at home. The number of such products with a microbicidal claim is increasing rapidly, although their impact on the microbial flora, notably in terms of emerging antimicrobial resistance has not been documented. With increasing evidence that microbicides can lead to bacterial resistance and cross-resistance to antibiotics, concerns have been expressed regarding the indiscriminate used of microbicidal products. This review aims to provide up-to-date information on the use of microbicides in the healthcare settings.
Sterilization methods available in healthcare facilities for sterilizing medical devices and instruments include autoclave, ethylene oxide gas and hydrogen peroxide (H2O2) gas plasma. Plasma-based sterilization technology using H2O2 was applied in the 1990s in healthcare settings. With the plasma-based sterilization systems a number of medical devices and instruments can be sterilized safely and rapidly, although the systems are unsuitable for processing such items as lengthy narrow lumened devices, linens, cellulose (paper) and liquids. Economic efficiency is also an important advantage of plasma-based sterilization technology. To promote safe and effective sterilization in healthcare facilities and prevent transmission of pathogens associated with contaminated medical devices, instruments or materials, progressive plasma-based sterilization processes are required with the ability to sterilize a wider range of patient-care items with shorter cycle times.
Viruses are important human pathogens causing substantial mortality and morbidity as well as economic damage. The lack of vaccination strategy and viral resistance to antiviral chemotherapy reemphasize the need for microbicides to eliminate or control viral outbreak. The activity and interactions of microbicides with the viral particle has been far less studied than their effects on bacteria. In addition, differences in virus size and structure as well as the diversity of efficacy test protocols used add to the fragmentation of information and the general lack of understanding of virucides. This chapter is focusing on the use of microbicides to destroy or control the transmission of viruses. The test methodologies are reviewed together with the general virucidal efficacy of different microbicides. Finally, the mechanisms of virucidal action of a number of microbicides are described as well as virus survival to microbicidal exposure.
Low temperature sterilization has been highlighted since the development of plastic made single use of medical devices and the appearance of more and more sophisticated endoscopic tools whose constitutive materials could not bear high temperature processing.After reviewing ideal criteria of gaseous proceeding the two families of sterilizing gaseous agents, the tow families of gas, alkylating agents and oxidizing ones are reviewed, as well as new technologies based on the use of cold plasmas. Their efficacy, management and drawbacks are considered. If alkylating agents such as ethylene oxide or formaldehyde have been used for many decades their drawback (toxicity for patients, staff and environment, mutagenicity or dangerous handling) banished them in many countries. Oxidizing agents are more promising despite their corrosion power on many materials. Among them, hydrogen peroxide and ozone seem to have good characteristics if properly used. In order to enhance their efficacy, several technologies have been developed in recent years using cold plasmas to increase production of free radicals. Some have been approved and are already in field use in certain countries.Combination of several adapted technologies could be a solution to a problem which is not totally solved to the present days.
Objective:
Dental implants, otherwise uncompromised, are occasionally found to be date-expired within intact or opened packages, denying their clinical use unless they can be reliably re-sterilized and made equivalent in reaction to new implants within receiving bone sites. This investigation identified an FDA-approved low-temperature gas plasma sterilization approach –in residual hydrogen peroxide (H2O2) vapor at low pressure, restoring even grossly contaminated dental implants to sterility within an hour and renewing their surface qualities to those of as-manufactured implants with regard to their support for attachment and growth of human alveolar osteoblasts.
Method:
Studies were conducted on actual date-expired dental implants of three different types, as packaged as well as after deliberate contamination with Candida albicans or adventitious atmospheric organisms, through microbiological broth-based and agar-based assays to prove sterility and through tissue culture assays with human alveolar osteoblasts to prove renewed cellular attachment and growth characteristics. The cells’ activity was assessed by cell’s activity test MTT assay. Furthermore, cells’ attachment profile were examined by Scanning Electron Microscopy (SEM) and differential interference contrast (DIC) light microscopy
Result:
Osteoblasts’ growth and viability were confirmed by statistically equivalent outcomes for as-manufactured implants and clean/re-sterilized (by H2O2 gas plasma) implants, judged by cellular mitochondrial activity assays (MTT), differential interference contrast (DIC) light microscopy, and SEM. In this study, ANOVA followed by HSD Tukey test was used to statistically analyze the collected data.
Conclusion:
The results demonstrated that date-expired dental implants could be safely and effectively restored to conditions generally associated with the good clinical performance of osseointegated cpTi devices.
This article describes a study on the sterilization and high level disinfection using plasma oxidation and dehydrogenation process in high frequency glow discharge and an experimental comparison of an inductive energy storage pulse power source, from the view point of alternative method for ethylene oxide chemical disinfection process. Antibacterial effect of the pulse-excited atmospheric pressure discharge is compared in He/O2, He/N2 and atmospheric pressure nitrogen streamer plasma. Optimum mixture ratio of nitrogen and oxygen was studied in microwave plasma, 2.45 GHz at the reduced pressure 50 to 100 Pa. In He - N2 - O2 mixture gas based on the synergistic effect of oxygen radical and UV radiation and the performance of the antibacterial effect was demonstrated with biological indicators: Bacillus atrophaeus ATCC 9372 and Geobacillus stearothermophilus ATCC 7953.
Recent technological development enabled non-thermal treatment over a large area and large volume at the atmospheric pressure. Along with industrial applications such as surface cleaning and fictionalization, applied research in biotechnology is also carried out, including treatment of living tissues in medical applications, inactivation of pathogenic microorganisms, and improvement of bio-compatibility of implants used for extra-cellular matrix. ...
In this review the potential applications of cold atmospheric gas
plasmas are presented with particular reference to the problems of
contamination of foods by biological agents. In addition to the
accidental contamination of food, the very real threat arising from the
deliberate contamination of the human food chain is also considered. The
evidence that has been gained for the efficacy of cold plasmas in
inactivating a wide range of biological agents is briefly surveyed. This
is followed by an examination of previous work in which various
types of foodstuffs have been successfully treated using cold gas
plasmas. The need to demonstrate that the quality attributes of treated
foods is not adversely affected is stressed. Finally, the role which gas
plasmas may have in decontaminating food processing equipment is
considered.
Resistance to antibiotics threatens our ability to control bacterial pathogens. It is clear that the persistence of cells containing resistance determinants is promoted by the strong selective pressure imposed by antibiotic use. This problem has been exacerbated by inappropriate and excessive use of antibiotics in both medicine and animal production. Concern has also been raised that inappropriate use of biocides contributes to the selection of resistant bacterial strains. This may occur because detoxification mechanisms for biocides and antibiotics are shared, or via selection for biocide resistance genes that are physically linked to antibiotic resistance genes and their mobile DNA vectors. In this brief review I will illustrate the latter phenomenon using the evolutionary history of the class 1 integron as an example, and then examine whether the increasing trend towards indiscriminate use of biocides in homes and consumer products might result in the selection of novel genetic elements that will have negative and unpredictable consequences for human health.
The term 'biocide' is widely used to denote a chemical agent that possesses antiseptic, disinfectant or preservative activity. Viruses are not the most resistant microorganisms to biocides and it is generally accepted that the presence or absence of a lipid envelope and virus size play a important role in their sensitivity to these agents. Overall, the viricidal activity of biocides is generally less well documented than their bactericidal, sporicidal or fungicidal efficacy. Furthermore, the lack of a standard testing protocol, the complexity of studying virus survival after disinfection and the range of viral models and markers used, make the analysis of information difficult. Consequently, information obtained with other microorganisms such as bacteria, spores and yeast are often used as the basis of explaining the viricidal activity of biocides. From the comparatively few studies undertaken on the mechanisms of action of viricides, it has emerged that although most act by altering viral capsid structure, few damage viral nucleic acid. In addition, the alteration of viral markers, such as antigenic structure and DNA polymerase, as well as structural damage to the capsid do not always reflect loss of viral infectivity. As for viral resistance to disinfection, only a few mechanisms have been identified; the formation of viral aggregates being probably the most important. Yet, the clinical relevance of viral resistance to biocides remains to be determined.
Studies about interaction of plasmas with microorganisms usually focus on bacteria, bacteria spores or fungal spores; little attention has been paid to plasma treatment of fungal species in their vegetative state. The aim of this work is to evaluate the effect of air plasma treatment at atmospheric pressure on mycelia of the agricultural relevant fungal species Ascochyta pinodella and Fusarium culmorum concerning growth inhibition and morphologic alterations. Radial growth measurements on plasma-treated and heat-treated mycelia plugs and light microscopy imaging of isolated and plasma-treated hyphae were carried out. Growth inhibition of the vegetative state of fungi due to plasma treatment was found as well as deformation and disruption of hyphae.
IntroductionThe importance of viral human infectionsEffective use of disinfectants against virusesEvaluation of viricidal activityMechanisms of viricidal actionViral resistance to biocide inactivationOther viricidal processesGeneral remarksReferences
Prion is an infectious particle composed of an abnormal isoform of the prion protein (PrPSc) and causes prion diseases such as bovine spongiform encephalopathy (BSE), Creutzfeldt-Jakob disease (CJD) and scrapie. Host cells express cellular prion protein (PrPC), which plays roles in normal functions such as anti-oxidative stress. PrPSc is derived from PrPC and produced by conformational conversion. Prion is notorious as a resistant pathogen, being difficult to inactivate with conventional sterilization procedures. Therefore, to prevent prion-caused iatrogenic diseases, the use of appropriate procedures to inactivate prions is important. For examples, alcohol treatment, autoclave (121˚C, 20 min) and γ-ray irradiation, which are used for disinfection, antisepsis or sterilization of viruses and bacteria, are not effective against prion. This is a fundamental review of prions and methods of their inactivation.
Dimethylmethylene blue (DMMB) has been used to photoinactivate a number of model viruses, including VSV, in RBC suspensions under conditions that preserve in vitro RBC properties during storage. The relative sensitivity of duck HBV (DHBV) and VSV to photoinactivation by DMMB was investigated by performing an indirect immunofluorescence assay (IFA) using primary duck hepatocyte (PDH) cultures or a standard plaque assay for the respective viruses.
DMMB was added to 45-percent Hct, WBC-reduced, oxygenated AS-3 RBCs at 10-, 1-, and 0.1-microM concentrations. Samples (1-mm thick) were illuminated with 5.4-mW per cm(2) of red light for 2 or 9 seconds. Unilluminated samples without DMMB or with 10 microM DMMB served as control.
DHBV and VSV were rapidly photoinactivated by DMMB in a concentration and light-dose-dependent fashion. Neither virus was substantially inactivated by incubation with DMMB in the dark. For a given light exposure, DHBV required a concentration of DMMB one-one hundredth that of VSV to achieve approximately the same level of inactivation.
DHBV appears to be considerably more sensitive than VSV to DMMB photoinactivation. Photoinactivation in 45-percent Hct RBCs can be achieved in seconds by using micromolar quantities of dye.
The transmission of mycobacteria by bronchoscopes has been reported several times in the last years. To explore methods to prevent transmission of tuberculosis in this way, we sterilized contaminated bronchoscopes with low-temperature hydrogen peroxide gas plasma sterilization.
Bronchoscopes were contaminated with Mycobacterium tuberculosis and decontaminated with a washer/disinfector ("normal washing"). Some were additionally disinfected with glutaraldehyde ("intensive washing"). Afterward the bronchoscopes were sterilized by low-temperature hydrogen peroxide plasma sterilization.
After normal washing, 8/17 samples had positive results by culture, and 7/17 had positive results by nucleic acid amplification technique. After intensive washing, all samples had negative results by culture, and 10/25 had positive results by nucleic acid amplification technique; after sterilization with low-temperature hydrogen peroxide plasma sterilization, all samples had negative results by culture and nucleic acid amplification technique.
Washing of bronchoscopes, as performed normally, is not sufficient for decontamination of bronchoscopes. Additional disinfection is recommended. If the nucleic acid amplification technique is used for diagnostic procedures, sterilization by low-temperature hydrogen peroxide plasma sterilization is recommended to avoid false-positive results.
To estimate process parameters for non-thermal methods of antimicrobial inactivation, the half-cycle method is very often used. However, the essential premise of this method of estimation, the independence of microbial inactivation kinetics from the microbial load, seems not to be true. Consequently, the attainment of the sterility assurance level as recommended by the pharmacopoeias by a process which has been validated using the half cycle method is not guaranteed. For the evaluation of such chemo-thermo disinfection processes, the quantification of remaining hepatitis B virus DNA (HBV-DNA) traces on the surface of instruments is a useful tool. An infection can be excluded if a decrease of the HBN3-DNA residues on the instruments below the minimum infective dose can be demonstrated. Using the signal amplification technique to detect HBV-DNA on instruments, the safety of an reprocessing procedures can be improved.
Human hepatitis B virus (HBV) is a worldwide public health problem with chronic carriers at risk for developing cirrhosis and hepatocellular carcinoma. Accidental nosocomial infections from inadequately disinfected equipment or exposure to blood and body fluids from patients are major routes. To solve such problems, disinfectants to inactivate HBV must be validated. Duck hepatitis B virus (DHBV) is accepted as a surrogate for HBV, due to their similar sensitivities to disinfectants and its safety. Ducklings are used for disinfectant efficacy assays; however, the same virus titer is obtained using duck embryonic hepatocytes. Viral titration in disinfectant efficacy assay is conducted using Southern hybridization of infected duck serum. However, this test requires radioisotopes. Therefore, disinfectant assessment protocols were developed using duck embryonic hepatocytes with polymerase chain reaction (PCR) or nested PCR. The ease of handling, lowered cost and enhanced sensitivity make PCR desirable. Chicken embryonic hepatocytes were applied to DHBV disinfectant efficacy assay. Results were consistent and could be used under certain conditions. The virucidal activities of two quaternary ammonium chloride disinfectants, n-alkyl dimethyl benzyl ammonium chloride and alkyl dimethyl benzyl ammonium chloride (10C-12C) were compared and effective concentrations were 1200 and 1800 ppm, respectively. Efficacies of these disinfectants were validated using real-time quantitative PCR. Results confirmed that the efficacy of n-alkyl dimethyl benzyl ammonium chloride was higher than alkyl dimethyl benzyl ammonium chloride (10C-12C). This assay was useful for rapid discrimination of killing potentials of disinfectants. In conclusion, these assays can be applied to other viruses that are unable to cause CPE in cell cultures and broadened the utility of DHBV as animal model for HBV.
A sterilization process with the use of RF-generated (13.56 MHz) CF(4)/O(2) gas plasma was optimized in regards to power, flow rate, exposure time, and RF-system type. The dependency of the sporicidal effect on the spore inoculum positioning in the chamber of the RF systems was also investigated. Dried Bacillus stearothermophilus ATCC 7953 endospores were used as test organisms. The treatments were evaluated on the basis of survival curves and corresponding D values. The only parameter found to affect the sterilization process was the power of the RF system. Higher power resulted in higher kill. Finally, when the samples were placed more than 3-8 cm away from a centrally placed electrode in System 2, the sporicidal effect was reduced. The results are discussed and compared to results from the present literature. The RF excitation source is evaluated to be more appropriate for sterilization processes than the MW source.
This study evaluated the suitability of some disinfection and sterilization methods for use with microdialysis probes. Disinfection or sterilization should minimize the tissue inflammatory reaction and improve the long-term health of rats on study and ensure the quality of data obtained by microdialysis sampling. Furthermore, the treatment should not negatively impact probe integrity or sampling performance. The techniques chosen for evaluation included two disinfection methods (70% ethanol and a commercial contact lens solution) and two sterilization methods (hydrogen peroxide plasma, and e-beam radiation). Linear microdialysis probes treated by these processes were compared to untreated probes removed from the manufacturer's packaging as if sterile (the control group). The probes were aseptically implanted in the livers of rats and monitored for 72 hours. The parameters chosen to evaluate probe performance were relative sample mass recovery and the relative in vivo extraction efficiency of the probe for caffeine. Post mortem bacterial counts and histopathology examination of liver tissue were also conducted. The probes remained intact and functional for the entire study period. The methods tested did not acutely alter the probes although hydrogen peroxide plasma and contact lens solution groups showed reduced extraction efficiencies. Minimal tissue damage was observed surrounding the probes and acute inflammatory reaction was mild to moderate. Low numbers of bacterial colonies from the implantation sites indicates that the health of animals in this study was not impaired. This was also true for the control group (untreated probe).
Since important agents of viral nosocomial infections like hepatitis B and C viruses and norovirus do not replicate sufficiently in cell culture systems, disinfectants with suspected efficacy against these viruses must be evaluated by different methods. Besides molecular approaches and indirect tests, the use of surrogate viruses with similar biophysical properties and genomic structure allows the assessment of virucidal efficacy of chemical disinfectants in quantitative suspension tests. Furthermore, insights into the survival of these viruses in the environment are possible. In recent years, duck hepatitis B virus and bovine viral diarrhoea virus have been tested as surrogates for hepatitis B and C viruses. Feline calicivirus serves as a surrogate for the group of norovirus. By including these viruses in inactivation experiments, valuable data from suspension tests can be derived on the virucidal efficacy of chemical disinfectants. Even in vivo tests using fingerpads of adult volunteers can be performed with these animal viruses without risk of infection. In contrast to in vitro examinations, the results of these tests allow use recommendations of chemical disinfectants for outbreak situations and daily routine disinfection.
The sporicidal effect of 20 different radio-frequency plasma processes produced by combining five different gas mixtures [O(2), Ar/H(2) (50/50%), Ar/H(2) (5/95%), O(2)/H(2) (50/50%), O(2)/H(2) (95/5%)] with four power/pressure settings were tested. Sporicidal effects of oxygen-containing plasmas were dependent on power at low pressure settings but not at high pressure settings. In the absence of oxygen no power dependency was observed at either high or low pressure settings. Survivor curves obtained with the use of nonoxygen plasmas typically had a tailing tendency. Only a mixture-optimized Ar/H(2) (15/85%) plasma process was not encumbered by tailing, and produced a decimal reduction time (D value) below 2 min for Bacillus stearothermophilus spores. Scanning electron microscopy showed that a CF(4)/O(2) plasma did more damage to the substrate than the 15/85% Ar/H(2) plasma. The present results indicate that UV irradiation inactivation is swift and power and pressure independent. Additionally, it is produced at low energy. However, it is not complete. Inactivation through etching is highly power and pressure dependent; finally, inactivation by photodesorption is moderately power and pressure dependent. A sterilization process relying on this mechanism is very advantageous because it combines a highly sporicidal effect with low substrate damage.
In this study, we evaluated gas plasma surface sterilization methods in a specific sterilizer. We have introduced a new monitoring method using 0.4 microm pore size membranes, which in this study gave the information corresponding to 3000 exposed biological indicators per treatment cycle. This enabled us to compare the fraction of inoculates that showed no growth after exposure for 30 different locations in the chamber, and hereby identify weak and strong spots in the chamber with regard to sporicidal effect. Membranes were also used to expose a broad spectrum of soil bacteria for plasma treatment at four different conditions. The organisms were identified using PCR and sequencing. The test showed that Bacillus stearothermophilus spores were inactivated at the slowest rate among the tested microorganisms. Further alpha-proteobacteria (Gram negative) seemed more sensitive than the rest of the tested organisms. The microspot evaluation approach has been a most useful tool in the assessment of sterilization performance in sterilizers that do not have clear measurable parameters related to the sterilization.
Electrophysiology and ablation cardiac catheters, which come in contact with blood during clinical use, are required to be non-pyrogenic (<20 endotoxin units (EU)/device). This study aimed to quantify the residual endotoxin load in reprocessed devices as a mandatory step to guarantee safe reuse. We monitored the pyrogenic status of the device (n=61) in three fundamental steps of the reprocessing protocol: after clinical use, after decontamination-cleaning treatments and after complete reprocessing, including sterilization by hydrogen peroxide gas plasma. Finally, a depyrogenation test was produced for evaluating the depyrogenation efficiency of the sole hydrogen peroxide sterilization treatment. Results showed that standard clinical use did not represent a source for endotoxin contamination, while the use of tap water and manual cleaning processing could increase the pyrogenic load in a significant way. The introduction of the sterilization by hydrogen peroxide gas plasma resulted in effective reduction of the endotoxin contamination and in safe reprocessing of 15 of 15 clinically used catheters. In addition, tests conducted on in vitro spiked catheters showed that initial pyrogenic loads of 40, 80, 200EU/device were reduced to less than 11EU/device. Depyrogenation testing demonstrated efficiency in endotoxin reduction of more than 62 times (1.8log). These results show the determining role of hydrogen peroxide gas-plasma sterilization in the reduction of pyrogenic load on medical devices. Considering actual hygienic requirements at single-use device reprocessing, hydrogen peroxide gas-plasma sterilization can be considered as an efficient treatment at non-lumen cardiac electrophysiology catheter reprocessing.
The use of a surrogate virus, namely duck hepatitis B virus (DHBV), has been recommended for testing the virucidal activity of chemical biocides against hepatitis B virus. To date, however, this model has not been recognized as a standard test in European countries, as its laboratory use is associated with considerable difficulties. As previous studies have demonstrated, several alternative procedures may improve the validation of DHBV infection in a cell culture system. Using indirect immunofluorescent antigen staining and the light cycler real-time polymerase chain reaction (PCR) technique, the virucidal activity of peracetic acid (PAA), povidone-iodine (PVP-I) and formaldehyde was tested against DHBV obtained from congenitally infected ducks or prepared from the transfected hepatoma D2 cell line. The results demonstrated that inactivation of DHBV from the D2 cell line was achieved with lower concentrations of the biocides and within shorter exposure time intervals. These lower concentration-exposure time values for DHBV from D2 cells in comparison with DHBV from infected ducks indicated a higher sensitivity of the virus derived from D2 cells. In addition, concentrations of PAA and PVP-I that significantly inactivated DHBV in suspension tests were not able to destroy the viral genome. In conclusion, DHBV from congenitally infected ducks should be used for virucidal testing of chemical biocides against DHBV; DHBV prepared from D2 cells is unsuitable due to its higher sensitivity to biocides. Indirect immunofluorescent staining allows reliable detection of DHBV infectivity, whereas the hepadnavirucidal effect can be evaluated by quantitative PCR.
To assess the performance and limitations of a reprocessing protocol for nonlumen electrophysiology catheters by testing the sterility of reprocessed devices and defining the maximum number of reprocessing cycles sustainable by the device in hygienically safe conditions.
Simulated use, reprocessing, and testing of the catheters.
Microbiology and virology department of a public health diagnostic laboratory.
Seventy-three catheters were collected after clinical use on patients. The first group of devices was tested for sterility after 1 cycle of reprocessing. By the repetition of simulated use (blood inoculated with bacteria) and reprocessing (decontamination, cleaning, and hydrogen peroxide gas plasma sterilization), we obtained 39 sample devices reprocessed 2 times, 26 reprocessed 3 times, 28 reprocessed 4 times, 36 reprocessed 5 times, and 22 reprocessed 6 times. Devices were cultured for 28 days in trypticase soy broth.
We tested 208 catheters with 6 cycles of reprocessing and 4 inoculated bacteria species. No devices tested positive for the inoculated strains until the fourth cycle of reprocessing. One of 35 catheters showed the growth of the inoculated strain Bacillus subtilis after 5 cycles of reprocessing, and 1 of 22 catheters showed growth of this organism 6 cycles. After the second reprocessing, 7 of 36 devices showed growth of gram-negative bacteria other than the strain inoculated.
Reprocessing according to the reprocessing protocol was insufficient to guarantee device sterility after 5 reuses. Cleaning with enzymatic solution revealed good cleaning properties with efficient bioburden reduction. Storage intervals of longer than 24 hours during reprocessing should be avoided to limit contamination or bacterial overgrowth. Technical considerations suggest the introduction of reprocessing procedures only in hospitals with considerable workloads.
The efficacy of three proprietary glutaraldehyde disinfectants and their component bases was assessed using the duck hepatitis B virus (DHBV) model. Inactivation of infectivity of undiluted serum containing 10(6.8) ID50/ml DHBV was assessed after a mixture with an equal volume of disinfectant had stood at room temperature for 10 min. A dried spill of infectious serum was simulated using sterile filter paper disks, saturated with serum containing DHBV, dried and then exposed to test disinfectant for 10 min. Residual infectivity, and hence the reduction in virus titre, was determined by inoculation of dilutions of the treated samples into 1-day-old ducklings. A greater than 3 log10 reduction in virus titre could be demonstrated for the disinfectants as well as for some of their component bases. Disinfectant activity varied according to the method of viral presentation but a reduction of exposure time from 10 to 2.5 min did not diminish activity. The experimental protocol permits a comparative and quantitative assessment of the efficacy of both established and new disinfectants.
Three commercial disinfectants (two quaternary formulations and one phenolic) were tested against human hepatitis B virus (HHBV). The treated virus was assayed for infectivity by the chimpanzee assay and for morphological alteration by the Morphological Alteration and Disintegration Test. The same agents were tested against duck hepatitis B virus in a duck hepatocyte infectivity assay. It is apparent that human and duck hepatitis viruses were relatively susceptible to disinfection, becoming noninfectious after < or = 10 min of contact with the disinfectant. The Morphological Alteration and Disintegration Test accurately predicted activity in the two infectivity tests. The anti-human hepatitis B virus effect of the low-level quaternary ammonium germicides is a novel finding and suggest that members of the family Hepadnaviridae are relatively susceptible to chemical agents.
Between March 1986 and September 1990, 67 of 243 cardiac transplant recipients in outpatient care at our clinic became hepatitis B virus surface antigen (HBsAg) positive after operation. The HBsAg of 63 patients belonged to the subtype ay, suggesting a common source of infection. These 63 cases and 103 controls with negative hepatitis B virus (HBV) serology were studied in order to analyse the outbreak. The sources of infection were patients who were chronic HBsAg carriers. Infection was transmitted at the time of endomyocardial biopsy, if performed on the same day and in the same room after biopsy of an HBsAg positive patient. The most likely mode of HBV transmission was droplet contamination of instruments and/or medication vials used for subsequent patients. Performing biopsies on HBsAg positive and negative patients in separate rooms resulted in the termination of the outbreak.
The susceptibility of duck hepatitis B virus (DHBV) to the virucidal effects of sodium hypochlorite (NaOCl) and sodium dichloroisocyanurate (NaDCC) was compared to hepatitis B virus (HBV) with the aim of using the duck as a model for studying HBV disinfection. Using viral DNA polymerase (DNAP) as a target, inhibition of DNAP activity by chlorine disinfectants was found to be concentration-dependent but independent of contact time. Two minute exposure of minimal effective concentrations of sodium hypochlorite (domestic bleach: 3600 ppm and industrial bleach: 3180 ppm) and sodium dichloroisocyanurate (3000 ppm available chlorine) to DHBV- and HBV-rich plasma totally inhibited DNA polymerase activity. DHBV particles in DHBV-carrier duck plasma (10(4.5) ID50/mL) were treated with these concentrations and inoculated intravenously into 18 one-day old ducklings (six animals/disinfectant). Analysis of plasma (0, 7 and 14 days post-infection) and post-mortem liver (14 days post-infection) by DNA hybridization techniques showed that DHBV DNA was undetectable in samples from all animals inoculated with disinfected virus particles. However, post-inoculation plasma and liver of 18 of 18 control ducklings inoculated with untreated virions were positive for DHBV DNA. These results show for the first time that total inhibition in vitro of hepadnavirus DNA polymerase activity by chemical disinfectants is predictive of inactivation of infectivity in vivo.
In the course of a study conducted in 1992 through 1994 of the efficacy of screening blood donors for antibodies to hepatitis C virus (HCV), we found that two patients had acquired hepatitis C after cardiac surgery, with the transmission apparently unrelated to blood transfusions. Because their surgeon had chronic hepatitis C, we sought to determine whether he was transmitting the virus to his patients.
Of 222 of the surgeon's patients who participated in studies of post-transfusion hepatitis between 1988 and 1994, 6 contracted postoperative hepatitis C, despite the use of only seronegative blood for transfusions. All six patients had undergone valve-replacement surgery. Analyses were performed to compare nucleotide sequences encompassing the hypervariable region at the junction between the coding regions for envelope glycoproteins E1 and E2 in the surgeon, the patients, and 10 controls infected with the same HCV genotype.
The surgeon and five of the six patients with hepatitis C unrelated to transfusion were infected with HCV genotype 3; the sixth patient had genotype 1 and was considered to have been infected from another source. Thirteen other patients of the surgeon had transfusion-associated hepatitis C and were also infected with genotype 1. The average net genetic distance between the sequences from the five patients with HCV genotype 3 and those from the surgeon was 2.1 percent (range, 1.1 to 2.5 percent; P < 0.001), as compared with an average distance of 7.6 percent (range, 6.1 to 8.3 percent) between the sequences from the patients and those from the controls. The results of phylogenetic-tree analysis indicated a common epidemiologic origin of the viruses from the surgeon and the five patients.
Our findings provide evidence that a cardiac surgeon with chronic hepatitis C may have transmitted HCV to five of his patients during open-heart surgery.
Although about 1 percent of surgeons are infected with hepatitis B virus (HBV), transmission from surgeons to patients is thought to be uncommon. In July 1992, a 47-year-old woman became ill with acute hepatitis B after undergoing a thymectomy in which a thoracic-surgery resident who had had acute hepatitis B six months earlier assisted.
To determine whether the surgeon transmitted HBV to this patient and others, we conducted chart reviews, interviews, and serologic testing of thoracic-surgery patients at the two hospitals where the surgeon worked from July 1991 to July 1992. Hepatitis B surface antigen (HBsAg) subtypes and DNA sequences from the surgeon and from infected patients were determined.
Of 144 susceptible patients in whose surgery the infected surgeon participated, 19 had evidence of recent HBV infection (13 percent). One of the hospitals was selected for additional study, and none of the 124 susceptible patients of the other thoracic surgeons at this hospital had evidence of recent HBV infection (relative risk, infinity; 95 percent confidence interval, 4.7 to infinity). No evidence was found for any common source of HBV other than the infected surgeon. The HBsAg subtype and the partial HBV DNA sequences from the surgeon were identical to those in the infected patients. Transmission of the infection was associated with cardiac transplantation (relative risk, 4.9; 95 percent confidence interval, 1.5 to 15.5) but not with other surgical procedures. The surgeon was positive for hepatitis B e antigen and had a high serum HBV DNA concentration (15 ng per milliliter). Our investigations identified no deficiencies in the surgeon's infection-control practices.
In this outbreak there was surgeon-to-patient HBV transmission despite apparent compliance with recommended infection-control practices. We could not identify any specific events that led to transmission.
Nosocomial transmission of hepatitis B virus (HBV), associated with interventional procedures, has been attributed to its survival on improperly decontaminated instruments. To date, guidelines for chemical disinfection of potentially contaminated heat-sensitive instruments have been based largely on extrapolation of data from in-vitro disinfectant testing. Direct infectivity testing has not been possible for HBV because of the lack of a practical culture assay or susceptible experimental animal model. In this study the related duck hepadnavirus was used to simulate in-vivo transmission of a HBV during surgery, and to evaluate the effectiveness of 2% glutaraldehyde disinfection of surgical laparoscopes. Multiple laparoscopic liver biopsies were performed on 'biohazardous' duck hepatitis B (DHBV) positive ducks. Laparoscopes were then subjected to different disinfection regimes using 2% glutaraldehyde, and residual infectivity tested by placing their tips into the peritoneal cavities of uninfected four-day-old ducklings. Direct transmission of DHBV occurred in all ducks when laparoscopes were not washed. Rinsing with water lowered the transmission rate to 64% and no infection transmission occurred after 5 min of contact time with the disinfectant. In contrast, previous in-vitro studies had shown complete viral inactivation after a shorter period of disinfection. It is postulated that the longer inactivation time observed in our study may be a result of surface interactions of virus and instrument, interfering with disinfectant access or activity. Tests of instrument surface samples for viral DNA by the polymerase chain reaction (PCR) did not correlate with transmission of virus infection in vivo. PCR is an inappropriate test for evaluating the efficacy of disinfectant action despite its sensitivity. This in use method will allow testing of other decontamination procedures and their effectiveness on more complex surgical instruments.
Studies were conducted to determine the capability of a hydrogen peroxide gas plasma sterilization process to inactivate several types of viruses. Six test agents were used: HIV type 1, human hepatitis A virus, respiratory syncytial virus, vaccinia, herpes simplex virus type 1, and poliovirus type 2.
The test viruses were suspended in cell culture medium and dried on the bottom of sterile glass petri dishes. The inoculated dishes were processed in the hydrogen peroxide gas plasma system for half the normal sterilization cycle time. Four inoculated carriers for each virus were used in two separate half cycles. Infectivity of the test viruses and cytotoxicity to the indicator cell lines were assayed.
The hydrogen peroxide gas plasma sterilization process produced inactivation of the six viral test agents under these experimental conditions. The reduction in viral titers ranged from 2.5 log10 to 5.5 log10, a 99.68% to 99.999% decrease.
These results clearly demonstrate the virucidal effectiveness of the hydrogen peroxide gas plasma sterilization process against both lipid and nonlipid viruses.
Low temperature hydrogen peroxide gas plasma has been developed as a new method of sterilizing medical products. The process has been shown to inactivate a broad spectrum of microorganisms, including resistant bacterial spores. A Sterility Assurance Level (SAL) of 10 -6 has been demonstrated for the process utilizing Bacillus stearothermophilus spores, the most resistant organism tested. Material compatibility studies have shown that the process is compatible with a wide range of metallic and non-metallic devices. When compared to r-irradiation, the low temperature hydrogen peroxide gas plasma has been found to affect the surface properties, i.e., wetting properties, of some non-metallic devices but not the bulk physical properties. Functionality studies have also shown that heat and moisture sensitive electronic, optical and mechanical devices are not adversely affected by exposure to the process.
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