Disinfection Treatment Research Articles

Evaluation of combined disinfection methods of infectious myonecrosis virus (IMNV) in seawater using Pacific white shrimp (Penaeus vannamei)

The global spread of infectious myonecrosis virus (IMNV) poses a serious threat to the shrimp aquaculture industry and urgent actions are needed to control its transmission and prevalence. Aquaculture water serves as an important route of IMN transmission, and disinfection of aquaculture water is crucial to ensure the health and stable production of shrimp. In this study, we introduced the purified IMNV into seawater and then subjected the seawater to different disinfection treatments (PMS, PMS + PVP-I and ClO2 + PVP-I) before culturing shrimp. By performing RT-qPCR tests on both the seawater and Pacific white shrimp (Penaeus vannamei) samples, we evaluated the effectiveness of the different disinfection methods in eradicating IMNV from the seawater. The results showed that peroxymonosulfate (PMS) could effectively reduce the viral load of IMNV in seawater samples. The combined disinfection approach (10 ppm) of PMS disinfection (combined with povidone‑iodine) followed by a standing time of at least 2 days, or 10 ppm chlorine dioxide disinfection (combined with povidone‑iodine) followed by a standing time of at least 4 days, were found to be successful in the efficient disinfection of IMNV. This research provides a method to effectively remove IMNV from marine aquaculture water, thereby contributing to reducing the risk of IMN disease transmission and providing a sound basis for the sustainable and healthy development of the shrimp aquaculture industry.

Determination of the possibility of the synthesis of Zn-Al layered double hydroxides, intercalated with peroxyanions, as a perspective solid disinfectant

Infectious diseases in the modern world pose a significant threat to humanity in the form of epidemics and pandemics. To prevent and combat them, it is necessary to carry out antiseptic and disinfectant treatments of various environments, household and industrial surfaces, as well as wounds of various origins. Double-layer hydroxides intercalated with peroxyanions as active oxygen compounds are promising materials for this. In order to determine the possibility of obtaining Zn-Al double-layer hydroxide intercalated with peroxylactic acid anions, samples were synthesized by the method of chemical co-precipitation in the presence of peroxylactic acid at controlled pH (8, 10) and t=20 ℃. The properties of the synthesized samples were investigated. The content of active oxygen (in terms of H2O2) was determined by the method of iodometric titration with the calculation of the percentage of hydrogen peroxide that was intercalated in double layered hydroxides, remained in the mother solution or was lost. The crystal structure was studied by X-ray phase analysis, the yield of samples was determined gravimetrically, and sedimentation was determined by measuring and normalizing the thickness of the sediment layer. It was found that the samples synthesized at pH=8 and 10 are biphasic and consist of an oxide phase and a double-layer hydroxide phase. The determined content of active oxygen (in terms of H2O2) in the samples synthesized at pH=8 (0.533 %) and at pH=10 (0.876 %) confirms the success of the synthesis of Zn-Al-peroxylactate double layered hydroxides. Synthesis at elevated pH is promising. A low percentage of H2O2 intercalation was revealed – 4.03–6.54 %, the majority of hydrogen peroxide (82.36-94.44 %) remains in the mother solution. The yield of the synthesized samples was determined to be 61.9 % and 79.5 % at synthesis pH of 10 and 8, respectively. The sedimentation properties of the samples were studied and their improvement was shown when the pH of the synthesis was increased

Formation potential of disinfection byproducts during chlorination of petroleum hydrocarbon-contaminated drinking water

Recent leaks of underground fuel storage tanks in the Pearl Harbor region have led to direct release of un-weathered petroleum hydrocarbons (PHCs) into drinking water sources, which then directly underwent chlorination disinfection treatment. Since the control of disinfection byproducts (DBPs) traditionally focuses natural organic matters (NOM) from source water and little is known about the interactions between free chlorine and un-weathered PHCs, laboratory chlorination experiments in batch reactors were conducted to determine the formation potential of DBPs during chlorination of PHC-contaminated drinking water. Quantitative analysis of regulated DBPs showed that significant quantities of THM4 (average 3,498 μg/L) and HAA5 (average 355.4 μg/L) compounds were formed as the result of chlorination of un-weathered PHCs. Amongst the regulated DBPs, THM4, which were comprised primarily of chloroform and bromodichloromethane, were more abundant than HAA5. Numerous unregulated DBPs and a large diversity of unidentified potentially halogenated organic compounds were also produced, with the most abundant being 1,1-dichloroacetone, 1,2-dibromo-3-chloropropane, chloropicrin, dichloroacetonitrile, and trichloracetonitrile. Together, the results demonstrated the DBP formation potential when PHC-contaminated water undergoes chlorination treatment. Further studies are needed to confirm the regulated DBP production and health risks under field relevant conditions.

Bioinspired Structures Made of Silicone Nanofilaments for Upcycling Waste Masks to Reusable N95 Respirators.

The increasing demand for personal protective equipment such as single-use masks has led to large amounts of nondegradable plastic waste, aggravating economic and environmental burdens. This study reports a simple and scalable approach for upcycling waste masks via a chemical vapor deposition technique, realizing a trichome-like biomimetic (TLB) N95 respirator with superhydrophobicity (water contact angle ≥150°), N95-level protection, and reusability. The TLB N95 respirator comprising templated silicone nanofilaments with an average diameter of ∼150 nm offers N95-level protection and breathability comparable to those of commercial N95 respirators. The TLB N95 respirator can still maintain its N95-level protection against particulate matter and viruses after 10 disinfection treatment cycles (i.e., ultraviolet irradiation, microwave irradiation, dry heating, and autoclaving), demonstrating durable reusability. The proposed strategy provides new insight into upcycle waste masks, breaking the existing design and preparation concept of reusable masks.

Pyro-catalysis for refrigerator disinfection via ubiquitous temperature fluctuation

Bacteria breeding in refrigerators can greatly compromise the quality and shelf life of stored food, posing a serious concern. The utilization of disinfection treatments, including ultraviolet irradiation, ozone, and precious metal ions, in refrigerators is constrained by the risk of secondary contamination and the associated high costs. To tackle this matter, we developed a pyro-catalytic disinfection technology that takes advantage of ubiquitous temperature fluctuations to trigger the generation of highly cytotoxic reactive oxygen species for antibacterial. By subjecting the synthesized Ba0.68Sr0.32TiO3 (BST) nanowires or composite patches (BST@C) to temperature fluctuations ranging from 5 to 25 °C for 40 cycles, the survival rates of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) were found to be below 5%. More importantly, the survival rates of S. aureus and E. coli were reduced to 19% and 34%, respectively, after only 80 refrigerator opening-closing cycles. This effective demonstration highlights the potential of the safety pyro-catalytic disinfection technology, which does not require additional energy consumption, and exhibits great compatibility with refrigerators.

Scenario-based assessment of fecal pathogen sources affecting bathing water quality: novel treatment options to reduce norovirus and Campylobacter infection risks.

Wastewater discharge and runoff waters are significant sources of human and animal fecal microbes in surface waters. Human-derived fecal contamination of water is generally estimated to pose a greater risk to human health than animal fecal contamination, but animals may serve as reservoirs of zoonotic pathogens. In this study, quantitative microbial risk assessment (QMRA) tools were used to evaluate the hygienic impact of sewage effluents and runoff water from municipalities and animal farms on surface and bathing waters. The human-specific microbial source tracking (MST) marker HF183 was used to evaluate the dilution of fecal pathogens originating from the sewage effluent discharge to the downstream watershed. As novel risk management options, the efficiency of UV-LED disinfection and wetland treatment as well as biochar filtration was tested on-site for the contamination sources. According to the dilution pattern of the MST marker HF183, microbes from wastewater were diluted (2.3-3.7 log10) in the receiving waters. The scenario-based QMRA revealed, that the health risks posed by exposure to human-specific norovirus GII and zoonotic Campylobacter jejuni during the bathing events were evaluated. The risk for gastroenteritis was found to be elevated during wastewater contamination events, where especially norovirus GII infection risk increased (1-15 cases per day among 50 bathers) compared with the business as usual (BAU) situation (1 case per day). The noted C. jejuni infection risk was associated with animal farm contamination (1 case per day, versus 0.2-0.6 cases during BAU). Tertiary treatment of wastewater with wetland treatment and UV-LED disinfection effectively reduced the waterborne gastroenteritis risks associated with bathing. Based on the experiences from this study, a QMRA-based approach for health risk evaluations at bathing sites can be useful and is recommended for bathing site risk assessments in the future. In case of low pathogen numbers at the exposure sites, the MST marker HF183 could be used as a pathogen dilution coefficient for the watershed under evaluation. The full-scale implementation of novel tertiary treatment options at wastewater treatment plants (WWTPs) as well as on-site runoff water treatment options should be considered for infection risk management at locations where scenario-based QMRA implies elevated infection risks.

Use of an eco‐friendly preservation technology as a strategy to increase the microbiological shelf‐life of a novel ready‐to‐eat salad containing vegetable by‐products

AbstractThe objective of this investigation was to evaluate different UV‐C irradiation doses in a novel ready‐to‐eat vegetable product containing vegetable by‐products (red beet leaves) and determine the microbiological shelf‐life and quality indicators during refrigerated storage (5 ± 1°C). During processing, no chemical disinfection was carried out and after the packaging step, 3 doses of UV‐C irradiation were applied (CTRL: 0 kJ/m2, L: 1 kJ/m2, M: 4 kJ/m2, and H: 7 kJ/m2) on the vegetable product studied (50% Creola purple lettuce, 25% beet leaves, and 25% arugula). It was observed that the intermediate dose (M) was the most suitable treatment since it could increase in six times its microbiological shelf‐life. Additionally, M was the one that showed the lowest loss of total polyphenols and the one that best maintained the antioxidant capacity (DPPH), probably attributed to the decrease in the activity of deterioration enzyme, PPO and higher ascorbic acid content at day 4. When evaluating % CO2/O2 on headspace of bags, UV‐C treatments reached earlier the dynamic equilibrium. Finally, all UV‐C irradiation treatments were successful against the simulated contamination. In that way, significant reductions of L. innocua and E. coli were found, with differences from up to 2 log cycles during storage. Finally, it can be concluded that UV‐C treatment can increase the microbiological shelf‐life of the novel ready‐to‐eat vegetable product, with quality indicators stabilization.Practical applicationsReady‐to‐eat salads present a short shelf‐life, which hinders their commercialization. As preservation technologies are required, UV‐C irradiation is an eco‐friendly alternative for its preservation as it has the potential to replace traditional disinfection treatments by reducing the water footprint of the total process. Therefore, since the UV‐C treatment is applied in the last step of the process (after packaging the product), microbiological contamination occurring in this type of vegetable products during processing is minimized. However, additional investigation is necessary to assess its suitability for a novel ready‐to‐eat salad containing horticultural by‐products.

On the Possibility of Using 5-Aminolevulinic Acid in the Light-Induced Destruction of Microorganisms.

Antimicrobial photodynamic inactivation (aPDI) is a method that specifically kills target cells by combining a photosensitizer and irradiation with light at the appropriate wavelength. The natural amino acid, 5-aminolevulinic acid (5-ALA), is the precursor of endogenous porphyrins in the heme biosynthesis pathway. This review summarizes the recent progress in understanding the biosynthetic pathways and regulatory mechanisms of 5-ALA synthesis in biological hosts. The effectiveness of 5-ALA-aPDI in destroying various groups of pathogens (viruses, fungi, yeasts, parasites) was presented, but greater attention was focused on the antibacterial activity of this technique. Finally, the clinical applications of 5-ALA in therapies using 5-ALA and visible light (treatment of ulcers and disinfection of dental canals) were described.

Assessing passive thermosyphon solar water heater as low-cost, sustainable water disinfection technology: Leveraging the Germicidal effect of copper and thermal convection loops

This study investigated the passive thermosyphon solar water heater (TSWH) as a domestic size point-of-use water disinfection treatment system for inactivating bacteria by utilizing both the germicidal properties of copper in heat exchanger and the heat generated in thermal convection loops. Additionally, life cycle analysis and manufacturing cost analysis were conducted to reveal its environmental and economic benefits. Initially, the germicidal capacity of copper tube against E. coli and total coliform in rapidly flowing polluted water was tested in laboratory settings with contact times ranging from 1.5 to 94 min. Without any additional heat, the copper tubes achieved 99.9% (log 3.01) removal of E. coli, and 99.24% (log 2.12) removal of total coliform after 94 min of contact. In the presence of heat (50–80 ºC), complete removal of the bacteria was achieved after only 1.5 mins of contact time at 50ºC. A domestic-sized passive TSWH with a copper tube heat exchanger was evaluated for disinfecting 20 L/day of microbiologically polluted tap water and synthetic groundwater in a field study. The average contact time of polluted water in copper tube heat exchanger was 5.58±1.2 min in the morning (with an outlet water temperature of 87.3 ºC), and 11.83±1.41 min in the afternoon (with an outlet water temperature of 78±5.1 ºC). These contact times and temperatures, achieved throughout the year, were sufficient to meet the required minimum for complete bacterial removal in the synthetic groundwater. Importantly, the system achieved complete inactivation of pathogens at pasteurization temperatures below 75 ºC, relying solely on the combined effect of copper and thermal convection loops, without pumps or electricity. Compared to an active TSWH using circulating pumps and controls, the passive system generated 62.2% less green house gas, had 55.5% lower cumulative energy demand and cost 323.3 $ compared to 544.64 $. Highlighting significant economic and environmental benefits, the passive TSWH offers a promising solution for disinfecting water in low-income areas with limited access to safe water.

Effect of NaClO disinfectant treatment on the yields, components and combustion characteristics of typical medical waste pyrolysis products

Medical waste with pathogenic bacteria is infectious and toxic, which could cause significant harm to the environment and human health without being adequately disposed of. Pyrolysis-incineration coupled technology can realize the rapid and efficient treatment of medical waste while reducing the generation of pollutants. Whereas, the NaClO disinfection treatment, which is a necessary process prior to transfer and disposal of medical waste, has not been sufficiently described in terms of its effect on the pyrolysis yield and components characteristics of medical waste. This study clarified the influence mechanism of NaClO disinfection treatment on the yields, components, and combustion characteristics of pyrolysis products derived from typical medical waste (cotton swab sticks, masks, and latex gloves). The results showed that NaClO disinfection treatment induced depolymerization of the internal structure of the polymer and increased pyrolysis tar and syngas at 400 °C. In addition, NaClO disinfection treatment reduced syngas quality, which was attributed to generating more CO2 and inhibiting alkynes gas production under medium-low pyrolysis temperatures. Furthermore, the condensation or cyclization of light components into heavy components in the tar increased the average double-bond equivalents and oxygen content, which was detrimental to tar ignition and combustion. Moreover, the combustion performance of char was improved because there was a tendency for the conversion of graphitic carbon to fatty carbon in the char. These findings elucidate the feasibility of pyrolysis-incineration coupled technology for the fast and effective treatment of medical waste.

Characterization and decontamination of deposited dust: a management regime at a museum

Deposited dust represents a nutritional niche for microflora. Inhibiting microflora-associated deposited dust is a critical approach to manage cultural heritage buildings. Knowledge on the effectiveness of commercial disinfection on microflora in a real field environment is limited. The present study aims to: (1) characterize deposited dust composition, and (2) assess the effectiveness of several commercial biocides/and an air ionizer on microflora-associated floor surface and air before and after treatment. Deposited dust was collected using a dust collector and microbial air sampling was conducted via a volumetric impactor sampler. Susceptibility of microorganisms to biocide/ionizer was performed in a naturally ventilated unoccupied room with a floor area of 18 m2. One-treatment protocol, a daily disinfection mode, was applied to each biocide/ionizer. The surface floor was adjacently sprayed by a biocide, and the ionizer was turned on for 30 min. Indoor deposited dust rates varied between 0.75 and 8.7 mg/m2/day with indoor/outdoor ratio of ~ 1:100. Ion concentrations of NH4+, Cl−, SO42− and NO3− were higher indoor than outdoor. The concentration of microorganisms-associated deposited dust averaged 106 CFU/g; 105 CFU/g and 104 CFU/g for bacteria, fungi and actinomycetes, respectively. A total of 23 fungal taxa were identified, with Aspergillus flavus, Asp. fumigatus and Asp. niger were the predominant taxa. Biocides quickly reduced floor surface and airborne microbial loads. The biocidal effect was time limited, as microflora loads increased again after ~ 4 days of the treatment protocol. Benzalkonium chloride (BAC) out-performed other biocides, showed a relatively permanent microbial inhibiting effect. The air ionizer reduced airborne microorganisms and increased surface floor ones. Characterizing of deposited dust (rate and composition) and choice an appropriate biocide may effectively reduce biodeterioration. Further real field treatment trials under various microenvironmental conditions are needed to determine the effectiveness of disinfection treatment.

Performance of full-scale rural wastewater treatment plants in the reduction of antibiotic-resistant bacteria and antibiotic resistance genes from small-city effluents

The main objective of this study was to evaluate the performance of full-scale rural wastewater treatment plants (WWTPs) in the reduction of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) from small-city effluents. Twenty full-scale WWTPs in rural Chile with different biological treatment technologies (vermifiltration (VF), activated sludge (AS) and biodisc (BD)) and disinfection treatments (chlorination (Cl) and UV irradiation (UV)) were monitored and studied in two campaigns: Campaign 1 (20 WWTPs) and Campaign 2 (6 WWTPs). In both campaigns, the rural WWTPs improved the water quality of the effluents very significantly (90%, 70%, and 40% reductions in TU, COD, and NH4+-N, respectively) and reduced ARB and ARG loads by 2–4 log units. All three biological treatments contributed to the final quality of the effluents, especially in terms of microbiological parameters, with statistically indistinguishable efficiencies between them. These results show the importance of rural WWTPs in improving the water quality of urban effluents while reducing microbiological risk and the spread of antibiotic resistance into the environment. The study demonstrates the utility of a non-centralized, self-managed wastewater treatment scheme that can be implemented in many sparsely populated areas around the world.

Study of helminth eggs (Ascaris suum) inactivation by anaerobic digestion and electrochemical treatment

Background The use of insufficiently treated wastewater or Faecal sludge in agriculture raises concerns because of the pathogen content. Helminth eggs (HE) are one of the most crucial pathogens for ensuring public health and safety. Widely used disinfection treatment methods do not guarantee the complete inactivation of helminth eggs. The current study evaluated the effectiveness of anaerobic digestion and electrochemical process on helminth (Ascaris suum) egg inactivation. Methods Lab-scale biochemical methane potential (BMP) assay was conducted by spiking A. suum eggs in a serum bottle. Total solid (TS), volatile solid (VS), pH, biogas production and its composition, and volatile fatty acids (VFA) were analyzed along with A. suum inactivation every third day for the initial 15 days and fifth day for 45 days. In the second set of experiments, a hypochlorite (4700 ppm) solution was generated by electrolysis of aqueous NaCl solution in a membrane-less electrochemical cell. The hypochlorite was diluted (940, 470, 235, and 156ppm) in wastewater, spiked with A. suum eggs and then examined for inactivation at regular intervals. Results The results of the anaerobic digestion treatment documented 98% inactivation of A. suum eggs (0.15 eggs/mL) in 35 days and remained at 0.14 eggs/mL until day 45. Correlation analysis revealed a positive relationship between non-viable eggs and pH and a negative relationship with all the other parameters. Electrochemical treatment achieved 10% inactivation at 940 ppm concentration in 24h. Conclusions This study revealed that the inactivation of A. suum eggs by anaerobic digestion or electrochemical treatment is a combined effect of more than one parameter.

Ultraviolet C as a method of disinfecting medical silicone used in facial prostheses: An in vitro study – Part 2

Statement of problemDisinfection is an important factor in preserving facial prostheses and maintaining tissue health. However, whether disinfection with ultraviolet C is an effective disinfection method is unclear. PurposeThe purpose of this in vitro study was to evaluate the effectiveness of irradiation with different exposure durations of an ultraviolet-C light-emitting diode in the disinfection of the silicone (A-588–1; Factor II) used in facial prostheses. Material and methodsA total of 216 specimens were prepared, contaminated by multispecies biofilm, and divided into 9 groups (n=24) for different treatments: chlorhexidine 0.12% (G CHG), ultraviolet-C light-emitting diode for 5 minutes (G UVC5), ultraviolet-C light-emitting diode for 10 minutes (G UVC10), ultraviolet-C light-emitting diode for 20 minutes (G UVC20), their respective untreated controls (Gcontrol CHG, Gcontrol UVC5, Gcontrol UVC10, Gcontrol UVC20), and dimethyl sulfoxide (G DMSO) as the negative control. Cell viability was measured by using the methyl tetrazolium salt (MTT) method. Two statistical analyses were performed. First, a 2×3 ANOVA was carried out to compare the control groups (Gcontrol UVC5, Gcontrol UVC10, and Gcontrol UVC20) and the experimental groups of UV-C LED light with different exposure durations (G UVC5, G UVC10, and G UVC20). The second analysis was performed using generalized linear models to compare the optical density of the groups (G UVC5, G UVC10, G UVC20, G CHG, and G DMSO). ResultsCell viability results demonstrated a microbial reduction after exposure to the ultraviolet-C light-emitting diode for 20 minutes (G UVC20) compared with untreated controls (P<.05). The 5- and 10-minute exposures were statistically similar to their respective control groups (P>.05). The 20 minutes exposure had the lowest average optical density value, being statistically different from the 5-minute exposure (P<.05). A 20-minute exposure to the ultraviolet-C light-emitting diode (G UVC20) was similarly effective when compared with the standard disinfection treatment (G CHG) and dimethyl sulfoxide (G DMSO) (P>.05). ConclusionsIrradiation with an ultraviolet-C light-emitting diode for 20 minutes decreased the in vitro microbial cell viability on the medical silicone used in facial prostheses.

Evaluation of Truck Cab Decontamination Procedures following Inoculation with Porcine Epidemic Diarrhea Virus and Porcine Reproductive and Respiratory Syndrome Virus.

This experiment aimed to evaluate commercially available disinfectants and their application methods against porcine epidemic diarrhea virus (PEDV) and porcine reproductive and respiratory syndrome virus (PRRSV) on truck cab surfaces. Plastic, fabric, and rubber surfaces inoculated with PEDV or PRRSV were placed in a full-scale truck cab and then treated with one of eight randomly assigned disinfectant treatments. After application, surfaces were environmentally sampled with cotton gauze and tested for PEDV and PRRSV using qPCR duplex analysis. There was a disinfectant × surface interaction (p < 0.0001), indicating a detectable amount of PEDV or PRRSV RNA was impacted by disinfectant treatment and surface material. For rubber surfaces, 10% bleach application had lower detectable amounts of RNA compared to all other treatments (p < 0.05) except Intervention via misting fumigation, which was intermediate. In both fabric and plastic surfaces, there was no evidence (p > 0.05) of a difference in detectable RNA between disinfectant treatments. For disinfectant treatments, fabric surfaces with no chemical treatment had less detectable viral RNA compared to the corresponding plastic and rubber (p < 0.05). Intervention applied via pump sprayer to fabric surfaces had less detectable viral RNA than plastic (p < 0.05). Furthermore, 10% bleach applied via pump sprayer to fabric and rubber surfaces had less detectable viral RNA than plastic (p < 0.05). Also, a 10 h downtime, with no chemical application or gaseous fumigation for 10 h, applied to fabric surfaces had less detectable viral RNA than other surfaces (p < 0.05). Sixteen treatments were evaluated via swine bioassay, but all samples failed to produce infectivity. In summary, commercially available disinfectants successfully reduced detectable viral RNA on surfaces but did not eliminate viral genetic material, highlighting the importance of bioexclusion of pathogens of interest.

Integrating meta-analysis with a quantitative microbial risk assessment model to investigate Campylobacter contamination of broiler carcasses

This study investigated the prevalence and associated risk factors of Campylobacter in South Korean broilers using a random-effects meta-analysis. Subsequently, to facilitate the design of preventive measures, the prevalence estimate from the meta-analysis was incorporated into a stochastic risk assessment model to quantify the Campylobacter contamination levels on broiler carcasses. The baseline model was developed based on the most common practices along the South Korean broiler processing line, with no interventions. Meta-analysis results revealed Campylobacter prevalence across the chicken supply chain in the following order: farms (60.6 % [57.3–63.4]), retail markets (43.90 % [24.81–64.99]), slaughterhouses (27.71 % [18.56–39.21]), and processing plants (14.50 % [3.96–41.09]). The model estimated a 52 % (36.1–70.8) Campylobacter prevalence at the end of chilling, with an average contamination level of 4.62 (2.50–6.74) log CFU/carcass. Sensitivity analysis indicated that Campylobacter fecal shedding (r = 0.95) and the amount of feces on bird exteriors (r = 0.17) at pre-harvest were the main factors for carcass contamination, while soft scalding (r = -0.22) and air chilling (r = -0.12) can serve as critical control points (CCPs) at harvest. Scenario analysis indicated that a combination of hard scalding, inside-outside bird washing, spray washing, and chlorinated water immersion chilling can offer a 30.9 % reduction in prevalence and a reduction of 2.23 log CFU/carcass in contamination levels compared to the baseline model. Apart from disinfection and sanitation interventions carried out during meat processing, the implementation of robust control measures is indispensable to mitigate Campylobacter prevalence and concentration at broiler farms, thereby enhancing meat safety and public health. Furthermore, given the high Campylobacter prevalence in the retail markets, future studies should explore the potential risk of cross-contamination at post-harvest stage.

A cluster of Candida parapsilosis displaying fluconazole-trailing in a neonatal intensive care unit successfully contained by multiple infection-control interventions.

This study aimed to investigate and contain a cluster of invasive candidiasis cases caused by fluconazole-resistant Candida parapsilosis (FRC) in a neonatal intensive care unit. Active surveillance was initiated. Direct observations of hand-hygiene compliance (HHC) among staff were conducted before and after the implementation of hand-hygiene (HH) education. Thirty-five environmental cultures were obtained. Phylogenetic analysis of FRC was performed using Fourier-transform infrared spectroscopy and microsatellite genotyping. A total of 14 patients (mean birth weight = 860 g, gestational age = 25 weeks) infected with FRC were identified using the fully automated analyzer, including 5 with clinical infection (three with catheter-related bloodstream infection, one with cutaneous infection, and one with fatal peritonitis) and 9 with colonization. The HHC rate in nurses before performing a sterile or aseptic procedure significantly improved after the HH education (P < .05). Sinks near the patients were contaminated with FRC. All FRC strains were confirmed to be susceptible to fluconazole using the CLSI method, and the microdilution procedure indicated a trailing effect. Phylogenetic analysis showed that all the fluconazole-trailing isolates from patients were clustered together and had the same genotype. Sinks were successfully decontaminated using accelerated hydrogen peroxide and drainage pipes were replaced. Ultraviolet-C decontamination was applied in the milk preparation room. No new cases were detected after the education and disinfection interventions. Sinks are an important reservoir of C. parapsilosis. Active surveillance, environmental hygiene, and constant staff education on maintaining a high level of HHC are necessary to limit the spread of C. parapsilosis.

Synthesis of Pt-MoS2 with enhanced photothermal and peroxidase-like properties and its antibacterial application.

Despite tremendous efforts, bacterial infection and contamination remain a major clinical challenge to modern humans. Nanozyme materials with stimuli-responsive properties are expected to be powerful tools for the next generation of antibacterial therapy. Here, MoS2 nanosheet was firstly prepared by liquid phase exfoliation method, and Pt-MoS2 hybrid biomaterial was then successfully synthesized by a simple self-reduction method. The Pt decoration significantly improves the photothermal effect of MoS2 nanosheet under 808 nm NIR laser irradiation. Besides, benefiting from the formation of heterogeneous structure, the Pt-MoS2 has significantly enhanced peroxidase mimetic catalytic activity, which can kill bacteria through catalysis of H2O2 to generate antimicrobial hydroxyl radicals. Moreover, the temperature rise brought about by NIR laser stimulation further amplifies the nanozyme activity of the composites. After treatment by the synergistic platform, both Staphylococcus aureus and Escherichia coli can be effectively inhibited, demonstrating its broad-spectrum antibacterial properties. In addition, the developed antibacterial Pt-MoS2 nanozyme have the excellent biocompatibility, which makes them well suited for infection elimination in biological systems. Overall, this work shows great potential for rationally combining the multiple functions of MoS2-based nanomaterials for synergistic antibacterial therapy. In the future, the Pt-MoS2 nanozyme may find wider applications in areas such as personal healthcare or surface disinfection treatment of medical devices.

Effectiveness of Lime (Citrus amblycarpa) Solution in Improving the Bacteriological Quality of Tableware

According to research on cutlery, it did not meet the bacteriological quality requirements for cleanliness because the disinfection process was not carried out. nfection process is necessary to enhance the cleanliness of cutlery, employing both chemical and natural methods. Lime zest is a natural ingredient that can be used for disinfection because it contains compounds such as alkaloids, tannins, steroids, triterpenoids, saponins, and flavonoids that are antibacterial by damaging cell membranes. The study's goal was to determine the efficacy of lime (Citrus amblycarpa) solution in improving the bacteriological quality of cutlery. This research is experimental, with a posttest-only control group design. The study included a total of 24 cutlery (plate) samples. We collected the data by examining the number of germs and Escherichia coli in each sample. Using Kruskal-Wallis, we analysed bacterial count data. Meanwhile, Escherichia coli could not be tested because all the samples were negative. The results showed that the cutlery (plate) before treatment did not contain Escherichia coli. By taking swab samples of the cutlery (plates), we found that the number of germs after disinfection treatment ranged from 1 to 33 colonies/cm2. Lime solution is ineffective at reducing the number of germs. It is recommended that the shop manager use running water and provide a place for draining and storing closed cutlery. Future researchers can conduct laboratory tests first to prove the effect of lime zest on Escherichia coli and carry out control treatments before concentration treatments.

SOIL FERTILITY AND HYDROGEOLOGICAL CONDITIONS OF THE PILOT PLOT LOCATED ON THE TERRITORY OF THE MODULAR BIOLOGICAL TREATMENT PLANT OF THE VILLAGE OF TASBOGET

Forecast calculations show that the possible use of surface runoff for agriculture and industrial production by 2040 will be no more than 24.4 km3/year, and taking into account non-productive losses it will be possible to use up to 21.5 km3/year of water resources [1]. On the territory of Kyzylorda province, the water factor acquires a leading role in the ecological sustainability of the natural environment. The main cause of environmental problems in the river basin is pollution and chronic water deficit. Therefore, providing the population and various sectors of the national economy with water in the required quantity and quality is the most important problem of our time. The level of anthropogenic pressures on water resources is determined by quantitative and qualitative indicators of water use, wastes of life activity entering the water source and their compatibility with the natural environment. Despite the reduction of return water discharges to water sources, water quality in all water bodies remains unsatisfactory [2]. At the present stage, both in Kazakhstan and abroad, to utilize the increasing volume of wastewater, the natural method of water treatment on irrigated fields has been increasingly used, with maximum use of nutrients contained in wastewater. In this case, irrigated fields can be considered as the final link of their natural disinfection treatment, which has socio-economic, environmental and technological aspects.