Pathogen Inactivation Efficacy Research Articles

Investigation of the foodborne pathogen inactivation efficacy of commercial baby bottle and knife sterilizers

Investigation of the foodborne pathogen inactivation efficacy of commercial baby bottle and knife sterilizers

Meta-Aerogel Electric Trap Enables Instant and Continuable Pathogen Killing in Face Masks.

The tremendous menace of the COVID-19 pandemic has underscored the urgency for antipathogen masks to stop the transmission of airborne infectious diseases. Most prevailing antipathogen masks manifest a slower sterilization rate that lags behind the pathogen momentum traversing the masks, thereby engendering an elevated susceptibility to infection. Here we tailor nanofibrous meta-aerogel electric traps, 3D-assembled from self-knotted carbon nanotube networks in an all rigid nanofibrous skeleton. This superior configuration revolves around the creation of numerous "dielectrophoretic-aerodynamic grippers", which are capable of directional manipulation of microbes toward the region of the lethal intensive electric field. Based on this, we present a disinfection unit comprising a pair of aerogel electrodes that demonstrate a rapid killing rate (>99.99% biocidal efficacy within 0.016 s) and long-term durability (12 h of continuous operation). Additionally, a microbutton lithium cell is employed as a power supply to fabricate an antipathogen face mask with this disinfection unit, which exhibits superior pathogen inactivation efficacy compared to commercial masks. This scalable biocidal protective equipment holds great potential for use in emergency medical services.

Application of the 222 nm krypton-chlorine excilamp and 280 nm UVC light-emitting diode for the inactivation of Listeria monocytogenes and Salmonella Typhimurium in water with various turbidities

Applicability of the 222 nm krypton-chlorine (KrCl) excilamp and 280 nm UVC light-emitting diode (LED-UVC) for water disinfection was identified in this study. Listeria monocytogenes and Salmonella Typhimurium were inactivated by the KrCl excilamp and LED-UVC treatments in water samples with varying turbidities. Inactivation curves were analyzed using the log linear model, and the derived inactivation rate constant (k) was approached as a function of turbidity using the exponential one-phase decay model. The integrated inactivation model was verified with turbidities other than those used at the experimental levels. Water disinfection efficacy by both the KrCl excilamp and LED-UVC treatments decreased with increasing turbidity, and the developed model predicted well the inactivation levels of both pathogens depending on the type treatment device, treatment dose, and sample turbidity. When applied to oyster or flatfish spindled samples, the LED-UVC showed higher pathogen inactivation efficacy in flatfish than oysters, as expected due to the lower turbidity of the flatfish spindled samples, but opposite results were observed with the KrCl excilamp. This result indicates that factors other than turbidity such as type of food and pathogen also should be considered. In this regard, further study is needed to identify the bactericidal mechanisms of these alternative UV-C irradiation technologies in water and food products.

Efficacy of activated persulfate in pathogen inactivation: A further exploration

Activated persulfate, a relatively new advanced oxidation process, has gained attention for its potential to ensure fresh produce safety. One of the major advantages is to avoid the formation of toxic chlorinated disinfection byproducts which are concerns for chlorine-based sanitizers. This study was aimed to investigate the efficacy of ferrous and alkaline activated persulfate in inactivating Escherichia coli O157:H7 and Listeria monocytogenes, with the primary focus on the effect of initial persulfate concentration, the effect of gradual addition of ferrous ion, and the stability of activated persulfate. The prepared 5-strain pathogen cocktails were treated by activated persulfate for 60 or 120 s. Sodium thiosulfate combined with phosphate buffer was used to quench the reaction. Both pathogens were plated onto non-selective agars for colony enumeration. The steady-state concentrations of sulfate and hydroxyl radicals were quantified in each activation conditions. The results showed higher initial persulfate concentration can lead to more pathogen reductions. About 8.50 log CFU/mL reduction was observed in 120 s after the initial persulfate concentration was increased to 80 mmol/L (ferrous activation on both pathogens) or 600 mmol/L (alkaline activation on L. monocytogenes). Gradual addition of ferrous ion into persulfate solution achieved more pathogen reductions than adding all ferrous ion at once. However, only the increases of reductions achieved by four sequential addition were significant (P < 0.05). In addition, the steady-state concentrations of both sulfate and hydroxyl radicals were found to be positively correlated with microbial reductions at all conditions. Furthermore, the pathogen inactivation efficacy of both ferrous and alkaline activated persulfate can be maintained for a relatively long period (up to 3 h).

Efficient inactivation of Pseudomonas aeruginosa by Cu/Co-α-NiMoO4 in visible light

The Cu/Co-α-NiMoO4 nanorods were fabricated by microwave hydrothermal process and characterized by various techniques. According to XRD/HRTEM/SAED/EDS analysis, the dopant ions were existed in the lattice of α-NiMoO4.The Cu/Co-α-NiMoO4 samples have capacity to inactivate the multidrug resistant Pseudomonas aeruginosa in visible light within 180 min. Also, they revealed the excellent stability with reusability. The scavengers test indicates that H2O2/OH/O2−/h+ play a crucial work for pathogen inactivation. Also, NBT assay suggested the enhancement of intracellular O2− production in Cu (33 folds) and Co doped (29 folds) α-NiMoO4. The FESEM analysis revealed dead bacteria cells by attack of active species on cell wall. Also, DNA fragmentation (gel electrophoresis) and protein degradation (Bradford assay) confirmed the inactivation of bacteria by active species. The evidence of superior biofilm penetration ability (69%) by doped photocatalyst was exhibited by well plate based crystal violet assay and TEM/EDS mapping. The band gap reduction, surface plasmon resonance effect, oxygen vacancy, electron-hole trapping by Cu2+/Co2+/Co3+, formation of intermediate energy band, and efficient separation of electron-hole pair were contributed for enhancement of the pathogen inactivation in visible light by doping of Cu and Co in α-NiMoO4. Also, Cu doped photocatalyst has slightly more pathogen inactivation efficacy than Co doped photocatalyst. The toxicity of photocatalyst was evaluated by using RAW 264.7 cells via MTT assay and the result revealed the toxicity. In conclusion, the Cu/Co-α-NiMoO4 photocatalyst can be applied for efficient inactivation of multidrug resistant pathogen in biological waste water treatment.

Effect of increased agitation speed on pathogen inactivation efficacy and in vitro quality in UVC-treated platelet concentrates.

Pathogen inactivation technologies require continuous development for adjustment to different blood components and products. With Theraflex UV-Platelets, a system using shortwave ultraviolet C (UVC) light (254 nm), efficient mixing of platelet concentrates (PCs) during UVC treatment is essential to ensure homogeneous illumination of the blood components. In this study, we investigated the impact of increasing the agitation speed during UVC treatment on pathogen inactivation capacity and platelet quality. The pathogen inactivation efficacy of UVC treatment was evaluated at two agitation speeds (110 vs. 180 rpm) using four different transfusion-relevant bacteria strains and three model viruses. Using a pool-and-split design, the in vitro quality of buffy coat-derived PCs stored in SSP+ additive solution for up to 7 days was assessed in UVC-treated PCs agitated at either 110 rpm (standard speed) or 180 rpm (increased speed) and in untreated controls. The higher agitation speed improved bacterial inactivation but did not influence viral inactivation. Metabolic activity (glucose consumption and lactate accumulation) in UVC-treated platelets was slightly higher than in untreated controls. Increases in parameters such as CD62P expression and annexin A5 binding indicated moderate activation of UVC-treated platelets. Quality variables for UVC-treated platelets agitated at standard vs. increased agitation speed were comparable. The mixing rate during illumination may be a process parameter for further development of UVC-based pathogen inactivation procedures for PLT concentrates.

Quantification of pathogen inactivation efficacy by free chlorine disinfection of drinking water for QMRA.

To support the implementation of quantitative microbial risk assessment (QMRA) for managing infectious risks associated with drinking water systems, a simple modeling approach for quantifying Log10 reduction across a free chlorine disinfection contactor was developed. The study was undertaken in three stages: firstly, review of the laboratory studies published in the literature; secondly, development of a conceptual approach to apply the laboratory studies to full-scale conditions; and finally implementation of the calculations for a hypothetical case study system. The developed model explicitly accounted for variability in residence time and pathogen specific chlorine sensitivity. Survival functions were constructed for a range of pathogens relying on the upper bound of the reported data transformed to a common metric. The application of the model within a hypothetical case study demonstrated the importance of accounting for variable residence time in QMRA. While the overall Log10 reduction may appear high, small parcels of water with short residence time can compromise the overall performance of the barrier. While theoretically simple, the approach presented is of great value for undertaking an initial assessment of a full-scale disinfection contactor based on limited site-specific information.

Pathogen inactivation – defining ‘adequate’ bacterial protection

Background and ObjectivesClinical acceptance of pathogen inactivation technologies depends on the demonstration of product safety, a minimal effect on product efficacy and the range and degree of pathogen inactivation. The major rationale for pathogen inactivation of platelets is the prevention of transfusion‐associated bacterial sepsis, a persistent problem despite multiple innovations to minimize and detect contamination.Materials and MethodsRecent reports and an empirical model are used to describe our current understanding of the efficacy of pathogen inactivation in improving platelet transfusion safety.ResultsOptimized in vitro testing evaluated the efficacy of riboflavin/UV light (Mirasol™), amotosalen/UVA (Intercept™) and UVC irradiation (THERAFLEX™ UV platelets) systems to effect a 102‐ &gt;106 fold reduction of a variety of bacterial species. All systems are less effective at inactivating bacterial spores. Reviewing reports on the level of pathogen inactivation at very low and high bacterial concentrations identifies areas for further scrutiny.ConclusionsClinical trials of pathogen inactivated platelets have focused on safety and clinical efficacy in terms of count increments and the prevention and treatment of bleeding. Little attention has been paid to efficacy in reducing the risk of bacterial transmission. Pathogen inactivation is expected to significantly reduce transfusion of contaminated platelet units, especially ones that are the result of low initial bacterial titres that are a systemic issue with the current testing methodology. Nevertheless, available data suggest that breakthrough cases of sepsis are likely and that their rates will vary substantially by technology.

Dynamic Effects of Free Chlorine Concentration, Organic Load, and Exposure Time on the Inactivation of Salmonella, Escherichia coli O157:H7, and Non-O157 Shiga Toxin–Producing E. coli

This study evaluated the dynamic effects of free-chlorine (FC) concentration, contact time, and organic load on the inactivation of Salmonella, Escherichia coli O157:H7, and non-O157 Shiga toxin-producing E. coli (STEC) in suspension. Bacterial cells from four strains each of Salmonella, E. coli O157:H7, and non-O157 STEC were inoculated separately or as a multistrain cocktail into solutions with varying FC concentrations. Lettuce or tomato extract was used to simulate the organic matter present during commercial fresh and fresh-cut produce wash operations. After exposure to FC for various lengths of time, the bacterial survival and water-quality changes were determined. In the absence of organic matter in a wash solution, pathogen inactivation is primarily a function of initial FC concentration (P < 0.0001), exposure time (P < 0.0001), and pathogen strains (P < 0.0001). In general, an over 4.5-log CFU/ml pathogen reduction was found after exposure to >0.5 mg/liter FC for over 30 s, or to >1.0 mg/liter FC for over 5 s. When the combination of FC concentration and contact time were less than or equal to the above conditions, survival of pathogens was strain dependant and ranked as: Salmonella > E. coli O157:H7 > non-O157 STEC. When organic matter was present in the wash solution, pathogen inactivation efficacy was specifically dependent on the residual FC concentration, which directly relates to both the initial FC concentration and the organic load. Prevention of pathogen survival in chlorinated produce wash solutions can be achieved by maintaining sufficient FC concentration and reducing the accumulation of organic matter.

Characteristics of the THERAFLEX UV-Platelets pathogen inactivation system – An update

Considerable progress has been made in the last decade in producing purer, safer, leucocyte and plasma reduced platelet concentrates (PC) with an extended shelf life. The development of different pathogen inactivation technologies (PIT) has made a substantial contribution to this trend. Preceding platelet PIT (INTERCEPT Blood System/Cerus Corporation, Concord, CA, USA; MIRASOL/Caridian BCT, Lakewood, CO, USA) are based on adding a photosensitive compound to PC. The mixture is then activated by UV light in the UVB and/or UVA spectral regions. A novel procedure, THERAFLEX UV-Platelets (MacoPharma, Mouvaux, France), was recently developed that uses short-wave ultraviolet light (UVC), without addition of any photoactive agent. This technology has proven to be highly effective in sterilising bacteria (the major cause of morbidity/mortality after platelet transfusion) as well as inactivating other transfusion transmitted DNA/RNA containing pathogens and residual leucocytes.Any PIT reflects a balance between the efficacy of pathogen inactivation and preservation of platelet quality and function. A broad spectrum of in vitro tests have become available for the assessment of platelet storage lesion (PSL), aiming to better predict clinical outcome and untoward effects of platelet therapy. Recent paired studies on the release of platelet-derived cytokines, as new platelet performance indicators, revealed a parallel increase in both THERAFLEX UV-treated and control PC throughout storage, supporting the notion that the bioavailability of platelet function is not grossly affected by UVC treatment. This is corroborated by some newer technologies for proteomic analysis, showing that the THERAFLEX UV-Platelets system results in limited disruption of integrin-regulating extracellular disulfide bonds and minimal protein alterations when compared to UVB and gamma irradiation. Moreover, standard in vitro parameters reflecting activation, metabolic activity and function of platelets are useful indicators of the overall performance of processing and storage and may be used as surrogate markers of platelet quality in vivo. However, there is some doubt as to what degree each marker alone or in combination reflects the true clinical outcome of transfused platelets. Therefore, an appropriate clinical programme has been initiated. The preclinical evaluation demonstrated tolerability and immunological safety of THERAFLEX UV-Platelets using an animal model. Additionally, the system has successfully completed two autologous Phase I trials on recovery and survival. Preliminary results suggest that the recovery and survival rates are consistent with other pathogen reduced platelet products that are licensed and in use. The method is currently under evaluation for safety and tolerability of UVC-treated platelets in healthy volunteers. Presently the THERAFLEX UV-Platelets system is the simplest and purest PIT easily adaptable to the existing blood bank setting. In the future, extension of the application range of the THERAFLEX UV-Platelets system is expected, in order to make this new technology compatible with a broad spectrum of collection and processing platforms, and with other blood products.

Quantification of Viral Inactivation by Photochemical Treatment with Amotosalen and UV A Light, Using a Novel Polymerase Chain Reaction Inhibition Method with Preamplification

Background. In evaluating a photochemical treatment process for inactivating parvovirus B19, there lacked simple culture methods to measure infectivity. The recently developed enzyme‐linked immunospot (ELISpot) infectivity assay uses late‐stage erythropoietic progenitor cells and is labor intensive and time consuming. We evaluated a novel, efficient polymerase chain reaction (PCR) inhibition assay and examined correlations with reductions in infectivity. Methods. Contaminated plasma was treated with 150 μmol/L amotosalen and 3 J/cm2 ultraviolet A light and then tested for DNA modification using conventional PCR inhibition and a novel preamplification approach. The novel assay subjected the samples to preamplification cycles using long‐template PCR, followed by quantitative PCR (QPCR) inhibition detection. Both approaches were tested for correlations with reductions in viral infectivity by comparing ELISpot assay results of identical samples. Results. The B19 preamplification inhibition assay showed detection ranges of 2–2.5 log and demonstrated quantitative correlation with up to a 5.8‐log reduction in viral infectivity in ELISpot results. Conventional PCR detected a >5 log reduction in amplification, correlated with a 4.4‐log reduction in viral infectivity. A range of 4‐log inhibition of hepatitis B virus DNA amplification was also achieved. Conclusions. The results demonstrated that a novel preamplification QPCR assay is a useful tool for predicting reductions in infectivity after photochemical treatment. This assay was extended to show utility in circumstances where practical in vitro assays are unavailable for the determination of the efficacy of pathogen inactivation.

Validation Studies in European Blood Centers To Evaluate Processing Whole-Blood-Derived or Apheresis Plasma Using the INTERCEPT Blood System Intended for Commercialization.

Introduction: INTERCEPT plasma (I-FFP) for transfusion is prepared with a photochemical treatment (PCT) system using amotosalen (S-59) and long-wavelength UVA light to inactivate a broad spectrum of blood-borne pathogens. For Phase 3 clinical trials, 6 US blood centers prepared an inventory of ~10,000 I-FFP units by processing ~250 mL whole blood-derived (WB) or apheresis (APH) plasma units using a prototype PCT system. In these trials, I-FFP effectively supported patients with congenital and acquired coagulopathies or TTP. The prototype PCT system has been modified to treat up to 635 mL of plasma in a single PCT process, yielding up to three ~200 mL doses while maintaining pathogen inactivation efficacy. This modified PCT system intended for commercialization was evaluated in process validation studies in 3 European blood centers under routine operating conditions. After processing with the commercial PCT system, the effect on coagulation factor activity and retention was assessed in APH plasma (Blood 2004; 104:746a) and, as reported here, in WB plasma.Methods: Whole blood and/or APH plasma units were collected at 3 European blood centers. Three-unit pools (~600 mL) of WB plasma were prepared. APH plasma (~600 mL) was collected using Autopheresis C (Baxter) or MCS+(Haemonetics) devices. Blood bank personnel processed a total of 60 WB plasma pools and 90 APH plasma units using the commercial PCT system. Baseline and I-FFP plasma samples were collected, frozen below -60°C, and sent to Cerus for assay of factors I (fibrinogen), II, V, VII, VIII, IX, X, XI, and XIII, proteins C (PC) and S (PS), and antithrombin III (AT). Alpha-2 antiplasmin (AP) was assayed by a reference laboratory. Comparative data from a representative subset of I-FFP units prepared for the Phase 3 trials using the prototype PCT system were obtained from samples collected during PCT processing and stored at ≤−70°C. Retention of activity is expressed as the proportion (%) of pre-treatment (baseline) activity remaining after PCT.Results: Retention of coagulation factor activity in WB and APH I-FFP prepared with the commercial PCT system (Comm) was 73–76% of baseline fibrinogen and FVIII activity, and 80–97% of baseline for factors II, V, VII, IX, X, XI, XIII, PC, PS, AT, and AP (Table). Retention of activity in I-FFP prepared with the commercial PCT system was similar to that of I-FFP prepared with the clinical prototype.Conclusion: The PCT system intended for commercialization provides multiple I-FFP doses with a single PCT process. Retention of coagulation factor activity in WB and APH plasma processed with the commercial PCT system was similar to that of I-FFP used in Phase 3 trials to effectively support patients with congenital and acquired coagulopathies or TTP. [Display omitted]

Windrow composting of municipal biosolids in a cold climate

This work investigated the technical feasibility of composting digested municipal biosolids using outdoor windrows in an extremely cold climate. Common belief suggested this was not possible because of low ambient temperatures and low biodegradable volatile solids content of the biosolids. Four trials were conducted: (i) batch started in late fall; (ii) batch started in winter; (iii) batch mixed and stored over winter, then started in spring; and (iv) batch mixed with leaves to improve heat generation. All recipes used 2.5 parts wood chips to 1 part biosolids (by volume). All four trials easily met the thermophilic temperatures required by the pathogen reduction criteria. Trial 2 (batch started in winter), however, did not achieve the thermophilic period until the following summer. The results suggest provisions be made for storage of material over winter. This means a 32% increase in area and a doubling of the system-turning capacity are needed. Practical observations included significant heat loss during turning and mixing, snowfall impact on oxygen supply and pile moisture content, wind direction impact on pile temperature profiles, and the impact of large frozen zones that may affect pathogen inactivation efficacy. Key words: municipal sludge, biosolids, windrow composting, pathogens, low temperature, winter.