Low-temperature Sterilization Research Articles

Vaporized Hydrogen Peroxide Gains Support as Low-Temperature Sterilization Method.

Vaporized Hydrogen Peroxide Gains Support as Low-Temperature Sterilization Method.

Analysis of sterilization efficiency and application cost of three low temperature sterilization methods.

This paper discusses the sterilization efficiency of three low temperature sterilization methods used in thermosensitive medical devices and makes a preliminary analysis of sterilization costs so as to provide the basis for reasonable selection of low temperature sterilizer in Central Sterile Supply Department. Medical devices compatible with the three sterilization methods were selected for sterilization, and two packaging materials were selected for the three low-temperature sterilization equipment according to the compatibility of the packaging materials. The equipment packed with the same packaging materials were sterilized for five times, and each low-temperature sterilizer was sterilized for a total of ten times. The sterilization effect, sterilization cycle time, energy consumption, and cost of the three sterilizers were compared. The cycle time of ethylene oxide sterilizer was 393.6min, and the cycle time of hydrogen peroxide low temperature plasma sterilizer was 56.1min. The cycle time of low temperature steam and formaldehyde sterilizer was 105.7min. The hydrogen peroxide low temperature plasma sterilizes single cycle power consumption at a maximum of 5 kWh. The single cycle energy consumption of compressed air ethylene oxide sterilizer is up to 12 l. In terms of sterilization application cost, hydrogen peroxide low temperature plasma sterilization has the highest cost, followed by ethylene oxide sterilization, and low temperature steam and formaldehyde sterilization is the lowest. The sterilization efficiency of hydrogen peroxide low temperature plasma sterilization is the highest, followed by low temperature steam and formaldehyde sterilization, and the lowest is ethylene oxide sterilization. The three low temperature sterilization methods can achieve effective sterilization of devices. Each hospital can choose an appropriate low temperature sterilization method according to the characteristics of thermosensitive instruments, turnover efficiency requirements, and financial status.

Microbicidal effect of negative air ion against Penicillium citrinum and quality control of Chinese bayberry

Chinese bayberry is susceptible to decay caused by Penicillium citrinum infection, which will cause food safety problems. Negative air ion (NAI) is a novel type of non-thermal microbicidal technology. This study presented NAI treatment's inhibitory effect and antimicrobial mechanism on P. citrinum isolated from Chinese bayberry fruit. The results indicated that NAI treatment had the optimal inhibitory effect on P. citrinum. P. citrinum cell membrane appeared to have visible wrinkles and damage after NAI treatment, which was observed by scanning electron microscopy (SEM) and transmission electron microscope (TEM). The contents of malondialdehyde (MDA), relative conductivity, soluble protein, soluble carbohydrate, nucleic acid leakage, and lactate dehydrogenase (LDH) in the culture medium increased obviously, which indicated that the membrane permeability of P. citrinum increased. With the laser confocal assay, NAI increased reactive oxygen species (ROS) accumulation and caused oxidative damage to membrane lipids. The membrane lipidomics of P. citrinum hyphae was determined by LC-MS. The results revealed that NAI treatment can hydrolyze the glycerophospholipid into phosphatidic acid (PA) and lysophosphatidylinositol (LPI). Besides, the results of energy metabolism illustrated that NAI treatment reduced the mitochondrial membrane potential (MMP) and energy charge of P. citrinum hyphae. Overall, the microbicidal effect of NAI consisted of two pathways: 1) NAI induced the accumulation of ROS and damaged the membrane structures; 2) NAI reduced mitochondrial membrane potential and caused energy metabolism disorders. In addition, the storage experiment proved that NAI could maintain the quality of Chinese bayberry by inhibiting microbial growth and delaying fruit decay. Hence, NAI hold promises as a potential low-temperature sterilization method for fruit and vegetable storage.

Simple methods for measuring milk exosomes using fluorescent compound GIF-2250/2276

Exosomes are small extracellular vesicles (EVs) found in culture supernatants, blood, and breast milk. The size of these nanocomplexes limits the methods of EV analyses. In this study, nitrobenzoxadiazole (NBD), a fluorophore, conjugated endosome-lysosome imager, GIF-2250 and its derivative, GIF-2276, were evaluated for exosome analyses. A correlation was established between GIF-2250 intensity and protein maker levels in bovine milk exosomes. We found that high-temperature sterilization milk may not contain intact exosomes. For precise analysis, we synthesized GIF-2276, which allows for the covalent attachment of NBD to the Lys residue of exosome proteins, and labeled milk exosomes were separated using a gel filtration system. GIF-2276 showed chromatographic peaks of milk exosomes containing >3 ng protein. The area (quantity) and retention time (size) of the exosome peaks were correlated to biological activity (NO synthesis suppression in RAW264.7 murine macrophages). Heat denaturation of purified milk-derived exosomes disrupted these indicators. Proteome analyses revealed GIF-2276-labeled immunomodulators, such as butyrophilin subfamily 1 member A1 and polymeric immunoglobulin receptor. The immunogenicity and quantity of these factors decreased by heat denaturation. When milk exosomes were purified from market-sourced milk we found that raw and low-temperature sterilization milk samples, contained exosomes (none in high-temperature sterilization milk). These results were also supported by transmission electron microscopy analyses. We also found that GIF-2276 could monitor exosome transportation into HEK293 cells. These results suggested that GIF-2250/2276 may be helpful to evaluate milk exosomes.

Does vaporized hydrogen peroxide sterilization affect the geometrical properties of anatomic models and guides 3D printed from computed tomography images?

BackgroundMaterial extrusion is used to 3D print anatomic models and guides. Sterilization is required if a 3D printed part touches the patient during an intervention. Vaporized Hydrogen Peroxide (VHP) is one method of sterilization. There are four factors to consider when sterilizing an anatomic model or guide: sterility, biocompatibility, mechanical properties, and geometric fidelity. This project focuses on geometric fidelity for material extrusion of one polymer acrylonitrile butadiene styrene (ABS) using VHP.MethodsDe-identified computed tomography (CT) image data from 16 patients was segmented using Mimics Innovation Suite (Materialise NV, Leuven, Belgium). Eight patients had maxillary and mandibular defects depicted with the anatomic models, and eight had mandibular defects for the anatomic guides. Anatomic models and guides designed from the surfaces of CT scan reconstruction and segementation were 3D printed in medical-grade acrylonitrile butadiene styrene (ABS) material extrusion. The 16 parts underwent low-temperature sterilization with VHP. The dimensional error was estimated after sterilization by comparing scanned images of the 3D printed parts.ResultsThe average of the estimated mean differences between the printed pieces before and after sterilization were − 0,011 ± 0,252 mm (95%CI − 0,011; − 0,010) for the models and 0,003 ± 0,057 mm (95%CI 0,002; 0,003) for the guides. Regarding the dimensional error of the sterilized parts compared to the original design, the estimated mean differences were − 0,082 ± 0,626 mm (95%CI − 0,083; − 0,081) for the models and 0,126 ± 0,205 mm (95%CI 0,126, 0,127) for the guides.ConclusionThis project tested and verified dimensional stability, one of the four prerequisites for introducing vaporized hydrogen peroxide into 3D printing of anatomic models and guides; the 3D printed parts maintained dimensional stability after sterilization.

The influence of low-temperature sterilization procedures on piezoelectric ceramics for biomedical applications

Piezoelectric materials are intensively investigated for usage in biomedical applications ranging from in vivo sensors and energy harvesters to implants for bone and neural cell stimulation. Besides the high requirements for reliability and low cytotoxicity, implantable materials must be sterilizable without losing their functionality. In this study, we investigate the impact of low temperature plasma sterilization and the associated cleaning routines on the piezoelectric properties of PZT, BCZT and KNN bulk ceramics. The stability of the piezoelectric response strongly depends on the material system, with BCZT ceramics showing the strongest decline in properties. Several factors were identified to contribute to this reduction of the piezoelectric coefficient, the most important being mechanical stress due to sample handling as well as chemical reactions during cleaning, disinfection and sterilization. The study highlights the importance of evaluating the impact of all influencing factors along the pre-implantation handling chain in the material selection process.

Targeting Zero—preventing Surgical Site Infections by Reducing Immediate Use Steam Sterilization (IUSS) of Surgical Instruments

Background This hospital went through a reorganization, at which time the IUSS (Immediately Use Steam Sterilization) rates were currently 25.95%, with an average of 200 cycles being ran each month. The SPD leadership made the decision, in partnership with Infection Prevention and hospital leadership, that the IUSS rates were a priority for the facility to prevent Surgical Site Infections (SSIs) and increase patient safety. The hospital defined the target of 2%, which the health system later followed as the system-wide target. Methods The facility made a “hard stop” date where IUSS cycles were no longer going to be allowed without OR (Operating Room) and SPD (Sterile Processing Department) leadership approval. Before the start date, education was given to surgeons, clinical teams, and SPD to ensure process understanding and risk of infection due to IUSS. The facility also recognized workflow as a large part of why instruments were being sent through IUSS, due to a backup in the department. Many items were purchased to increase workflow, such as a new washer, sonic, adding a pass-through window, a low-temperature sterilizer and replacing 3 sterilizers with newer models. The facility also purchased more instruments to create additional trays to accommodate the surgical volume. The Sterile Processing Department also underwent LEAN Kaizen events in both the clean and dirty sides to improve workflow and efficiency to prevent further IUSS. Results The facility saw an immediate reduction of IUSS cycles being performed and were able to drop below the goal of 2% after the first month of using the new process. The rate has continued to be below 2% for more than 5 months. Conclusions Communication and partnership between the OR, Infection Prevention and SPD proved to be beneficial and will continue to move the facility forward in a shared decision-making model in the future as improvement continues.

Forced convective heating for low-temperature sterilization.

A novel impermeable sterile pouch is developed to allow the forced convective heating mechanism for improving the sterilization cycle. The heating process is parametrically investigated to obtain an optimized condition in which a sterilization load is heated from 20 to 45 °C within 2min, and the forced convection is experimentally and numerically analyzed to find that the convection coefficient is dramatically increased to 450 W/m2K when compared with the conventional natural convection coefficient of 80 W/m2K. The optimized heating process is applied to a sterilization cycle using the impermeable pouch, and the overall sterilization cycle is found to be completed within 7.5min whose performance is validated by using a process challenge device.

Optical fibre based real-time measurements during an LDR prostate brachytherapy implant simulation: using a 3D printed anthropomorphic phantom

An optical fibre sensor based on radioluminescence, using the scintillation material terbium doped gadolinium oxysulphide (Gd2O2S:Tb) is evaluated, using a 3D printed anthropomorphic phantom for applications in low dose-rate (LDR) prostate brachytherapy. The scintillation material is embedded in a 700 µm diameter cavity within a 1 mm plastic optical fibre that is fixed within a brachytherapy needle. The high spatial resolution dosimeter is used to measure the dose contribution from Iodine-125 (I-125) seeds. Initially, the effects of sterilisation on the sensors (1) repeatability, (2) response as a function of angle, and (3) response as a function of distance, are evaluated in a custom polymethyl methacrylate phantom. Results obtained in this study demonstrate that the output response of the sensor, pre- and post-sterilisation are within the acceptable measurement uncertainty ranging from a maximum standard deviation of 4.7% pre and 5.5% post respectively, indicating that the low temperature sterilisation process does not damage the sensor or reduce performance. Subsequently, an LDR brachytherapy plan reconstructed using the VariSeed treatment planning system, in an anthropomorphic 3D printed training phantom, was used to assess the suitability of the sensor for applications in LDR brachytherapy. This phantom was printed based on patient anatomy, with the volume and dimensions of the prostate designed to represent that of the patient. I-125 brachytherapy seeds, with an average activity of 0.410 mCi, were implanted into the prostate phantom under trans-rectal ultrasound guidance; following the same techniques as employed in clinical practice by an experienced radiation oncologist. This work has demonstrated that this sensor is capable of accurately identifying when radioactive I-125 sources are introduced into the prostate via a brachytherapy needle.

Multifunctional DBD-Based Ozone Sterilizer with Ultrasonic Cavitation for Low-Temperature Treatment of Medical Tools

The development of a dielectric barrier discharge (DBD) sterilizer for cleaning, disinfection, and low-temperature sterilization in water saturated with ozone is described. The sterilizer consists of an ozone generator based on glow barrier dielectric discharge with flat electrodes covered with dielectric operated at a high-voltage power supply of 250 W. The 2.5-L sterilization bath is equipped with a 100-W ultrasound source to provide additional cleaning of complexly shaped objects. High ozone concentrations in water (up to 10 mg/L) are necessary for effective and complete sterilization of tools and is achieved by dissolving ozone in cooled water (∼ 10–15°C). The ozone concentration at the output of the ozone generator is 25 mg/L. The main characteristics of the ozone sterilizer with ultrasonic cavitation are given, and the effectiveness of this sterilizer in inactivating a number of microbiological objects is shown.

Inactivation of Prions by Low-Temperature Sterilization Technology Using Vaporized Gas Derived from a Hydrogen Peroxide–Peracetic Acid Mixture

Prion diseases are proteopathies that cause neurodegenerative disorders in humans and animals. Prion is highly resistant to both chemical and physical inactivation. Here, vaporized gas derived from a hydrogen peroxide–peracetic acid mixture (VHPPA) was evaluated for its ability to inactivate prion using a STERIACE 100 instrument (Saraya Co., Ltd.). Brain homogenates of scrapie (Chandler strain) prion-infected mice were placed on a cover glass, air-dried, sealed in a Tyvek package, and subjected to VHPPA treatment at 50–55 °C using 8% hydrogen peroxide and <10% peracetic acid for 47 min (standard mode, SD) or 30 min (quick mode, QC). Untreated control samples were prepared in the same way but without VHPPA. The resulting samples were treated with proteinase K (PK) to separate PK-resistant prion protein (PrPres), as a marker of the abnormal isoform (PrPSc). Immunoblotting showed that PrPres was reduced by both SD and QC VHPPA treatments. PrPres bands were detected after protein misfolding cyclic amplification of control but not VHPPA-treated samples. In mice injected with prion samples, VHPPA treatment of prion significantly prolonged survival relative to untreated samples, suggesting that it decreases prion infectivity. Taken together, the results show that VHPPA inactivates prions and might be applied to the sterilization of contaminated heat-sensitive medical devices.

Effect of Non-Concentrated and Concentrated Vaporized Hydrogen Peroxide on Scrapie Prions.

To date, there have been no studies on the sterilization of prions by non-concentrated and concentrated vaporized hydrogen peroxide (VHP) applied by the same instrument. Here, the effect of the two types of VHP applied using an ES-700 sterilizer on prions was investigated. Brain homogenate from scrapie (Chandler) prion-infected mice was spotted on a cover glass and subjected to ES-700 treatment in soft (non-concentrated VHP from 59% hydrogen peroxide) or standard (concentrated VHP from 80% hydrogen peroxide) mode. Proteinase K-resistant prion protein (PrPres), an indicator of the abnormal isoform of prion protein (PrPSc), was reduced by ES-700 treatment under several conditions: SFT1/4 (soft mode, quarter cycle), SFT1/2 (soft mode, half cycle), SFT1 (soft mode, full cycle), and STD1/2 (standard mode, half cycle). PrPres was detected after the first and second rounds of protein misfolding cyclic amplification (PMCA) of untreated samples, but was undetectable in SFT1/4, SFT1/2, SFT1, and STD1/2 treated samples. In a mouse bioassay, SFT1/2 and STD1/2 treatment of prions significantly prolonged survival time, suggesting that prion infectivity is reduced after ES-700 treatment. In summary, both non-concentrated and concentrated VHP inactivate prions and may be useful for the low-temperature sterilization of prion-contaminated medical devices.

Evaluation of Sterilization Performance for Vaporized-Hydrogen-Peroxide-Based Sterilizer with Diverse Controlled Parameters.

Hydrogen-peroxide-based low-temperature sterilization is a new sterilization technology for temperature-dependent medical devices. The effect of the process parameters of hydrogen-peroxide-based sterilizer on the sterilization performance of process challenge devices (PCDs) needs to be investigated. Sterilant amount, operating temperature, vacuum pressure, diffusion time, and chamber loading of the sterilizer on the sterilization performance of PCDs were adjusted. Seven PCDs with various morphologies and material containing biological indicators (BI) (EZTest, Geobacillus stearothermophilus) were used to evaluate the sterilization performance. The sterilization success rates of PCDs were 86, 71, and 57% with controlled temperature and pressure, diffusion time, and sterilant volume injection, respectively. The PCD material and structure also obviously affected sterilization performance. The sterilization of PCD A is the least successful for all parameters. Meanwhile, the sterilization of PCD B was influenced by the diffusion time and the sterilant injection volume. PCD B and PCD C were successfully sterilized by controlling the temperature and pressure. The weights and volume of the sterilization loading chamber resulted in a different sterilization performance. Sterilization performances of PCD 1, PCD 2, and PCD 3 were <70, <90, and 100%, respectively. Sterilant volume, sterilant diffusion time, pressure, temperature, PCD types, and chamber loading were proven to be important process parameters of sterilizer that affect the sterilization performance of vaporized-hydrogen-peroxide-based sterilizers.

Targeting Zero-Preventing Surgical Site Infections by Reducing Immediate-Use Steam Sterilization (IUSS)

Objective: To reduce the number of immediate-use steam sterilization (IUSS) cycles performed to below 2% to increase patient safety and decrease surgical site infections (SSIs). Methods: The facility decide to make a “hard stop” date at which IUSS cycles were no longer going to be allowed without operating room (OR) and Sterile Processing Department (SPD) leadership approval, based on standardized indications for IUSS cycles. Before the start date, extensive education was given to surgeons, OR clinical teams, and SPD team members to ensure understanding of the process and risk of infection due to IUSS. The facility also recognized that workflow was a large part of why instruments were being sent through IUSS cycles, due to a backup of sets in the department and because some items could not be processed before the next day. Many items were purchased to increase workflow capabilities: such as a new washer, sonic, adding a pass-through window, a low-temperature sterilizer, Also, 3 sterilizers were replaced with newer, more efficient models. The facility also purchased a large number of instruments to create new and additional trays to accommodate the surgical volume. The SPD also underwent LEAN Kaizen events on both the clean and dirty sides to improve workflow and efficiency to prevent further IUSS. Project Results: The facility saw immediately results in reduction of IUSS cycles being performed and were the department was able to drop below the goal of 2% after the first month of using the new process. The rate has continued to be &lt;2% for &gt;5 months. Communication and partnership between the OR, infection prevention staff, and SPD were beneficial and will continue to move the facility forward in a shared decision-making model as improvement continues in the future.Funding: NoneDisclosures: None

Comparative Evaluation of the Microbicidal Activity of Low-Temperature Sterilization Technologies to Steam Sterilization

Background: Most medical and surgical devices used in healthcare facilities are made of materials that are sterilized by heat (ie, heat stable), primarily steam sterilization. Low-temperature sterilization methods developed for heat and moisture sensitive devices include ethylene oxide gas (ETO), hydrogen peroxide gas plasma (HPGP), vaporized hydrogen peroxide (VHP), and hydrogen peroxide plus ozone. This study is the first to evaluate the microbicidal activity of the FDA-cleared VHP sterilizer and other methods (Table 1) in the presence of salt and serum (10% FCS). Methods: Brushed stainless steel discs (test carriers) were inoculated with test microbes (Table 1) and subjected to 4 sterilization methods: steam, ETO, VHP and HPGP. Results: Steam sterilization killed all 5 vegetative and 3 spore-forming test organisms in the presence of salt and serum (Table 1). Similarly, the ETO and the HPGP sterilizers inactivated the test organisms with a failure rate of 1.9% for each (ie, 6 of 310 for ETO and 5 of 270 for HPGP). Although steam had no failures compared to both ETO and HPGP, which demonstrated some failures for vegetative bacteria, there was no significant difference comparing the failure rate of steam to either ETO (P &gt; .05) or HPGP (P &gt; .05). However, the VHP system tested failed to inactivate all the test organisms in 76.3% of the tests (206 of 270; P &lt; .00001) (Table 1). Conclusions: This investigation demonstrated that steam sterilization was the most effective method, followed by ETO and HPGP and, lastly, VHP.Funding: NoneDisclosures: Dr. Rutala was a consultant to ASP (Advanced Sterilization Products)

Does Blood on “Dirty” Instruments Interfere With the Effectiveness of Sterilization Technologies?

Background: Surgical instruments that enter sterile tissue should be sterile because microbial contamination could result in disease transmission. Despite careful surgical instrument reprocessing, surgeons and other healthcare personnel (HCP) describe cases in which surgical instruments have been contaminated with organic material (eg, blood). Although most of these cases are observed before the instrument reaches the patient, in some cases the contaminated instrument contaminates the sterile field, or rarely, the patient. In this study, we evaluated the robustness of sterilization technologies when spores and bacteria mixed with blood were placed on dirty (uncleaned) instruments. Methods: Dirty surgical instruments were inoculated with 1.5105 to 4.1107 spores or vegetative bacteria (MRSA, VRE or Mycobacterium terrae) in the presence or absence of blood. The spores used were most resistant to the sterilization process tested (eg, Geobacillus stearothermophilus for steam and HPGP and Bacillus atrophaeus for ETO). Once the inoculum dried, the instruments were placed in a peel pouch and sterilized by steam sterilization, ethylene oxide (ETO), or hydrogen peroxide gas plasma (HPGP). These experiments are not representative of practice or manufacturer’s recommendations because cleaning must always precede sterilization. Results: Steam sterilization killed all the G. stearothermophilus spores and M. terrae when inoculated onto dirty instruments in the presence or absence of blood (Table 1). ETO failed to inactivate all test spores (B. atrophaeus) when inoculated onto dirty instruments (60% failure) and dirty instruments with blood (90% failure). ETO did kill the vegetative bacteria (MRSA, VRE) under the same 2 test conditions (ie, dirty instruments with and without blood). The failure rates for HPGP for G. stearothermophilus spores and MRSA were 60% and 40%, respectively, when mixed with blood on a dirty instrument. Conclusions:This investigation demonstrated that steam sterilization is the most robust sterilization process and is effective even when instruments were not cleaned and the test organisms (G. stearothermophilus spores and MRSA) were mixed with blood. The low-temperature sterilization technologies tested (ie, ETO, HPGP) failed to inactivate the test spores but ETO did kill the test bacteria (ie, MRSA, VRE). These findings should assist HCP to assess the risk of infection to patients when potentially contaminated surgical instruments enter the sterile field or are unintentionally used on patients during surgery. Our data also demonstrate the importance of thorough cleaning prior to sterilization.Funding: NoneDisclosures: Dr. Rutala was a consultant to ASP (Advanced Sterilization Products)

N95 reprocessing by low temperature sterilization with 59% vaporized hydrogen peroxide during the 2020 COVID-19 pandemic

BackgroundResponse to the COVID-19 pandemic by hospital systems has been strained by severe shortages in personal protective equipment (PPE), particularly N95 respirators. Recently, the Centers for Disease Control and Prevention endorsed decontamination strategies to prolong the lifespan of single use respirators. Battelle and Duke University have validated hospital protocols to decontaminate respirators using vaporized hydrogen peroxide (VHP) at 30%-35% concentrations. To prolong our supply of respirators, we evaluated and implemented VHP decontamination at 59% hydrogen peroxide concentration while detailing the effects of this process on the filtration efficiency and quantitative fit of single-use respirators. This study may help other health systems develop local solutions to their N95 mask shortage during this COVID-19 pandemic.MethodsN95 respirators (3M 8211 FF and 9210 FF) that were treated with 5 and 10 cycles of VHP by the V-PRO maX Low Temperature Sterilization System were evaluated quantitatively for filtration efficiency as well as with quantitative fit testing per Occupational Safety and Health Administration standards. A decontamination protocol was concurrently implemented at our institution. This process involved depositing used masks, reprocessing, and re-distributing treated masks efficiently back to frontline providers. Furthermore, we implemented patient safety officers on COVID-19/person under investigation units to ensure optimized donning/doffing of respirators through frontline provider education.ResultsThere were no statistically significant changes in mean filtration efficiency between the control and VHP-treated respirators. Furthermore, both treated and untreated respirators demonstrated fit factors above the minimum pass requirement.ConclusionsWe have successfully demonstrated that N95 respirator decontamination with VHP at 59% hydrogen peroxide can be safely utilized to decontaminate single-use N95 respirators without significant effects on filtration efficiency or quantitative fit testing. With the COVID-19 pandemic and N95 respirator shortage, health systems without access to commercial decontamination processes should investigate the viability of such a process in their facilities.

Reply to Randal W. Eveland regarding comparative evaluation of the microbicidal activity of low-temperature sterilization technologies to steam sterilization

Reply to Randal W. Eveland regarding comparative evaluation of the microbicidal activity of low-temperature sterilization technologies to steam sterilization

Evaluation of Low-Temperature Sterilization using Hydrogen Peroxide Gas Containing Peracetic Acid.

In low-temperature sterilization for the medical field, hydrogen peroxide sterilization is widely used for its safety. However, its low penetrability and residual amount of sterilant are major concerns. Recently, the combination of hydrogen peroxide and peracetic acid has been found to enforce sporicidal effect, with low concentration in hydrogen peroxide. The application of this finding in medical sterilization is still very limited. To elucidate the combination effect, we compare peracetic acid containing hydrogen peroxide gas sterilizer and conventional hydrogen peroxide gas (plasma) sterilizers. The sterilant penetrability was examined in hollow load process challenge devices with inner diameters of 1 and 2 mm and lengths of 1, 2, and 3 m. As a result, peracetic acid containing hydrogen peroxide gas sterilizer demonstrated total inactivation with all diameters and lengths and achieved the highest sterilant penetrability in this study. The amount of residual sterilant on the surface of the sterilized object was 4.2 μg/cm2, which corresponds to half amount of those of conventional hydrogen peroxide gas sterilizers. These results suggest that the addition of peracetic acid to hydrogen peroxide gas sterilizer can enhance sterilization efficiency and safety.

Is plasma sterilization the modality of choice of sterilization today for endourological procedures such as ureterorenoscopy and retrograde intrarenal surgery? A single-center retrospective evaluation of 198 patients.

Introduction:The prevalence of infective complications among patients undergoing Retrograde Intrarenal Surgery (RIRS) for renal stone is 1.7%-18%, including fever, Systemic Inflammatory Response Syndrome (SIRS) and sepsis. The infectious complications of RIRS can be minimised by strict aseptic precautions and plasma sterilization. The Sterrad Next Generation (Sterrad NX) System, a low-temperature sterilizer represents the next generation of low-temperature hydrogen peroxide gas plasma sterilizers. This study was conducted to evaluate the efficacy of plasma sterilization among patients undergoing ureterorenoscopy (URS) and RIRS. The primary endpoint of this study was incidence of septicemia or related complications. Till date, there is no study on the incidence of infection rate in RIRS in relation to a specific mode of sterilization.Material and Methods:This is a retrospective study comprising of 198 patients undergoing URS and/or RIRS. The parameters studied were incidence of post-operative fever, Systemic Inflammatory Response Syndrome (SIRS), pyelonephritis or septicemic shock.Results:Out of 198 patients, incidence of post-operative fever was 3.5%, SIRS was 1.7%, pyelonephritis was 0.7% and septicemic shock was 0%. This is statistically significantly low septicemia rate among patients undergoing URS and /or RIRS as compared to the available literature. No health hazards of plasma sterilization were noted. No damage to the endoscopes or instruments was noted.Conclusion:Sterrad NX based on hydrogen peroxide gas plasma (HPGP) technology is highly efficacious, safe and the modality for sterilization of instruments, including heat labile instruments such as semi rigid, flexible and chip on the tip endoscopes and other EndoUrology armamentarium.