How to achieve adequate quenching for DBP analysis in drinking water?

Quenching is an important step to terminate disinfection during preparation of disinfected water samples for the analysis of disinfection byproducts (DBPs). However, an incomplete quenching might result in continued reactions of residual chlorine, whereas an excessive quenching might decompose target DBPs. Therefore, an adequate quenching to achieve simultaneous disinfection termination and DBP preservation is of particular importance. In this study, the two-stage reaction kinetics of chlorine and three commonly used quenching agents (i.e., ascorbic acid, sodium thiosulfate, and sodium sulfite) were determined. Stopping quenching during the first stage prevented interactions of residual chlorine with natural organic matter. Complete quenching was achieved by minimizing the quenching time for ascorbic acid and sodium sulfite, while limiting the quenching time to less than 3 min for sodium thiosulfate. At the optimized quenching times, the molar ratios (MRs) of quenching agent to chlorine were 1.05, 1.10, and 0.75 for ascorbic acid, sodium sulfite, and sodium thiosulfate, respectively. The destructive effects of the three quenching agents on total organic halogen (TOX) followed the rank order of ascorbic acid (33.7-64.8 %) < sodium sulfite (41.6-72.8 %) < sodium thiosulfate (43.3-73.2 %), and the destructive effects on aliphatic DBPs also followed the rank order of ascorbic acid (29.5-44.5 %) < sodium sulfite (34.9-51.9 %) < sodium thiosulfate (46.9-53.2 %). For total organic chlorine (TOCl) and aliphatic DBPs, the quenching behavior itself had more significant destructive effect than the quenching agent type/dose and quenching time, but for total organic bromine (TOBr), the destructive effect caused by quenching agent type/dose and quenching time was more significant. High-dose, long-duration quenching enhanced the reduction of TOX, but had little effect on aliphatic DBPs. Additionally, the three quenching agents reduced the levels of halophenols (except for tribromophenol), while maintained or increased the levels of tribromophenol, halobenzoic/salicylic acids, and halobenzaldehydes/salicylaldehydes. To achieve adequate quenching for overall DBP analysis in chlorinated water samples, it is recommended to use ascorbic acid at a quenching agent-to-chlorine MR of 1.0 for a quenching time of < 0.5 h.

Effects of glutaraldehyde and povidone-iodine on apoptosis of grass carp liver and hepatocytes.

Since disinfectants are used all over the world to treat illnesses in people and other animals, they pose a major risk to human health. The comprehensive effects of disinfectant treatments on fish liver, especially the impacts on oxidative stress, toxicological effects, transcriptome profiles, and apoptosis, have not yet been fully analyzed. In the current investigation, healthy grass carp were exposed to 80 µg/L glutaraldehyde or 50 µg/L povidone-iodine for 30 days. First, the findings of enzyme activity tests demonstrated that the administration of glutaraldehyde could considerably increase oxidative stress by lowering T-SOD, CAT, and GPx and raising MDA. Furthermore, KEGG research revealed that exposure to glutaraldehyde and povidone-iodine stimulated the PPAR signal pathway. To further elucidate the transcriptome results, the relative expressions of related DEGs in the PPAR signal pathway were verified. Glutaraldehyde induced apoptosis in liver tissue of grass carp; however, it activated cytotoxicity and apoptosis in grass carp hepatocytes when exposed to glutaraldehyde or povidone-iodine. According to the current study, disinfectants can cause the impairment of the immune system, oxidative stress, and attenuation of the PPAR signal pathway in the liver of grass carp, making them detrimental as dietary supplements for grass carp, particularly in the aquaculture sector.

Adhesive Bond Strength of Restorative Materials to Caries-Affected Dentin Treated with Antimicrobial Photodynamic Therapy: A Systematic Review and Meta-Analysis.

Objective: This systematic review aimed to evaluate the adhesive bond strength of restorative materials to caries-affected dentin (CAD) treated with antimicrobial photodynamic therapy (aPDT) in comparison with conventional chemical disinfectants. Methods: Three databases, including the Web of Science, Scopus, and PubMed, were searched to address the focused question: "What is the effect of aPDT compared to conventional chemical disinfection techniques on the adhesive bond strength of restorative materials to CAD?." Search keywords included "dentin*" "adhes bond*" "caries-affected dentin" "photodynamic "photochemotherapy" "photosensitizing agent" "phototherapy" "photoradiation" "laser" "light activated" "photoactivated." A fixed-effects model was used in each meta-analysis and the inverse variance was used to calculate the standard mean difference (SMD). For evaluating the statistical heterogeneity, the Cochrane's Q test and the I2 statistics were used. The risk of bias was evaluated based on the Cochrane Collaboration's tool. Results: Fourteen studies were included in the qualitative as well as quantitative analysis. The results of the meta-analyses exhibited an SMD of 2.38% [95% confidence interval (CI): 2.03-2.73; p < 0.00001], indicating a statistically significant difference in the shear bond strength scores between the tested group (samples treated with aPDT) and the control group (i.e., favoring the sound dentin and/or conventional chemical disinfectants). Contrarily, an SMD of -1.46% (95% CI: -2.04 to -0.88; p < 0.00001) and -0.37% (95% CI: -0.70 to -0.03; p = 0.03) was observed, indicating a statistically significant difference in the microtensile bond strength (µTBS), as well as microleakage scores between the tested group (favoring the samples treated with aPDT) and the control group (i.e., sound dentin and/or conventional chemical disinfectants). Conclusions: Adhesive bond strength of restorative materials to CAD treated with conventional chemical disinfectants showed superior outcomes compared to photodynamic therapy (aPDT).

Premise Plumbing Pipe Materials and In-Building Disinfectants Shape the Potential for Proliferation of Pathogens and Antibiotic Resistance Genes.

In-building disinfectants are commonly applied to control the growth of pathogens in plumbing, particularly in facilities such as hospitals that house vulnerable populations. However, their application has not been well optimized, especially with respect to interactive effects with pipe materials and potential unintended effects, such as enrichment of antibiotic resistance genes (ARGs) across the microbial community. Here, we used triplicate convectively mixed pipe reactors consisting of three pipe materials (PVC, copper, and iron) for replicated simulation of the distal reaches of premise plumbing and evaluated the effects of incrementally increased doses of chlorine, chloramine, chlorine dioxide, and copper-silver disinfectants. We used shotgun metagenomic sequencing to characterize the resulting succession of the corresponding microbiomes over the course of 37 weeks. We found that both disinfectants and pipe material affected ARG and microbial community taxonomic composition both independently and interactively. Water quality and total bacterial numbers were not found to be predictive of pathogenic species markers. One result of particular concern was the tendency of disinfectants, especially monochloramine, to enrich ARGs. Metagenome assembly indicated that many ARGs were enriched specifically among the pathogenic species. Functional gene analysis was indicative of a response of the microbes to oxidative stress, which is known to co/cross-select for antibiotic resistance. These findings emphasize the need for a holistic evaluation of pathogen control strategies for plumbing.

Antifungal activity and mechanism of action of natural product derivates as potential environmental disinfectants.

There have been a considerable number of antifungal studies that evaluated natural products (NPs), such as medicinal plants and their secondary metabolites, (phenolic compounds, alkaloids), essential oils, and propolis extracts. These studies have investigated natural antifungal substances for use as food preservatives, medicinal agents, or in agriculture as green pesticides because they represent an option of safe, low-impact, and environmentally friendly antifungal compounds; however, few have studied these NPs as an alternative to disinfection/sanitation for indoor air or environmental surfaces. This review summarizes recent studies on NPs as potential fungal disinfectants in different environments and provides information on the mechanisms of inactivation of these products by fungi. The explored mechanisms show that these NPs can interfere with ATP synthesis and Ca++ and K+ ion flow, mainly damaging the cell membrane and cell wall of fungi, respectively. Another mechanism is the reactive oxygen species effect that damages mitochondria and membranes. Inhibition of the overexpression of the efflux pump is another mechanism that involves damage to fungal proteins. Many NPs appear to have potential as indoor environmental disinfectants. ONE-SENTENCE SUMMARY: This review shows the latest advances in natural antifungals applied to different indoor environments. Fungi have generated increased tolerance to the mechanisms of traditional antifungals, so this review also explores the various mechanisms of action of various natural products to facilitate the implementation of technology.

Estimation of alkali dosage and contact time for treating human excreta containing viruses as an emergency response: a systematic review.

Water, sanitation, and hygiene provisions are essential during emergencies to prevent infectious disease outbreaks caused by improper human excreta management in settlements for people affected by natural disasters and conflicts. Human excreta disinfection is required when long-term containment in latrines is not feasible on-site. Alkali additives, including lime, are effective disinfectants for wastewater and faecal sludge containing large amounts of solid and dissolved organic matter. The aim of this study was to determine the minimum dose and contact time of alkali additives for treating virus-containing human excreta in emergency situations. We used literature data collected by searching Google Scholar and Web of Science. The date of the last search for each study was 31th May 2023. Only peer-reviewed articles that included disinfection practices in combination with quantitative data for the physicochemical data of a matrix and viral decay were selected for data extraction. Two reviewers independently collected data from each study. We extracted datasets from 14 studies that reported quantitative information about their disinfection tests, including viral decay over time, matrix types, and physicochemical properties. Three machine learning algorithms were applied to the collected dataset to determine the time required to achieve specified levels of virus inactivation under different environmental conditions. The best model was used to estimate the contact time to achieve a 3-log10 inactivation of RNA virus in wastewater and faeces. The most important variables for predicting the contact time were pH, temperature, and virus type. The estimated contact time for 3 log inactivation of RNA virus was <2 h at pH 12, which was achieved by adding 1.8 and 3.1% slaked lime to wastewater and faeces, respectively. The contact time decreased exponentially with the pH of the sludge and wastewater. In contrast, the pH of the sludge and wastewater increased linearly with the slaked lime dosage. Lime treatment is a promising measure where long-term containment in latrine is not feasible in densely populated areas, as 1 day is sufficient to inactivate viruses. The relationship we have identified between required contact time and lime dosage is useful for practitioners in determining appropriate treatment conditions of human waste.

Antiviral Natural Products, Their Mechanisms of Action and Potential Applications as Sanitizers and Disinfectants.

Plant extracts, natural products and plant oils contain natural virucidal actives that can be used to replace active ingredients in commercial sanitizers and disinfectants. This review focuses on the virucidal mechanisms of natural substances that may exhibit potential for indoor air and fomite disinfection. Review of scientific studies indicates: (1) most natural product studies use crude extracts and do not isolate or identify exact active antiviral substances; (2) many natural product studies contain unclear explanations of virucidal mechanisms of action; (3) natural product evaluations of virucidal activity should include methods that validate efficacy under standardized disinfectant testing procedures (e.g., carrier tests on applicable surfaces or activity against aerosolized viruses, etc.). The development of natural product disinfectants requires a better understanding of the mechanisms of action (MOA), chemical profiles, compound specificities, activity spectra, and the chemical formulations required for maximum activity. Combinations of natural antiviral substances and possibly the addition of synthetic compounds might be needed to increase inactivation of a broader spectrum of viruses, thereby providing the required efficacy for surface and air disinfection.

Screening of natural extracts with anti-norovirus effects and analysis of this mechanism in grape seed extract.

Norovirus (NoV）is a major causative virus of viral gastroenteritis and requires a general disinfection method because it is resistant to common disinfectants such as ethanol and chlorhexidine. This study aimed to find natural extracts as candidates for versatile disinfectant ingredients. The antiviral effect of natural extracts against NoV can be evaluated using the feline calicivirus (FCV）-inactivation test and NoV virus-like particle (NoV-VLP）-binding inhibition test. In this study, screening of natural extracts with anti- NoV effects was performed using these two methods. Of the 63 natural extracts examined, 14 were found to have high FCV-inactivation and NoV-VLP-binding inhibitory effects. In addition, we evaluated the NoV-VLPbinding inhibitory effect of grape seed extract（GSE）containing proanthocyanidins under multiple concentration conditions and treatment times and determined that the binding inhibitory effect of GSE was concentration- and time-dependent. Electron microscopy showed that GSE-treated NoV-VLPs aggregated, distorted, and swelled, suggesting that GSE directly interacts with NoV particles. The results suggest that some natural extracts containing GSE can be used as components of disinfectants against NoV.

Protozoan-Priming and Magnesium Conditioning Enhance Legionella pneumophila Dissemination and Monochloramine Resistance.

Opportunistic pathogens (OPs) are of concern in drinking water distribution systems because they persist despite disinfectant residuals. While many OPs garner protection from disinfectants via a biofilm lifestyle, Legionella pneumophila (Lp) also gains disinfection resistance by being harbored within free-living amoebae (FLA). It has been long established, but poorly understood, that Lp grown within FLA show increased infectivity toward subsequent FLA or human cells (i.e., macrophage), via a process we previously coined "protozoan-priming". The objectives of this study are (i) to identify in Lp a key genetic determinant of how protozoan-priming increases its infectivity, (ii) to determine the chemical stimulus within FLA to which Lp responds during protozoan-priming, and (iii) to determine if more infectious forms of Lp also exhibit enhanced disinfectant resistance. Using Acanthamoeba castellanii as a FLA host, the priming effect was isolated to Lp's sidGV locus, which is activated upon sensing elevated magnesium concentrations. Supplementing growth medium with 8 mM magnesium is sufficient to produce Lp grown in vitro with an infectivity equivalent to that of Lp grown via the protozoan-primed route. Both Lp forms with increased infectivity (FLA-grown and Mg2+-supplemented) exhibit greater monochloramine resistance than Lp grown in standard media, indicating that passage through FLA not only increases Lp's infectivity but also enhances its monochloramine resistance. Therefore, laboratory-based testing of disinfection strategies should employ conditions that simulate or replicate intracellular growth to accurately assess disinfectant resistance.

Mechanisms of emerging resistance associated with non-antibiotic antimicrobial agents: a state-of-the-art review.

Although the development of resistance by microorganisms to antimicrobial drugs has been recognized as a global public health concern, the contribution of various non-antibiotic antimicrobial agents to the development of antimicrobial resistance (AMR) remains largely neglected. The present review discusses various chemical substances and factors other than typical antibiotics, such as preservatives, disinfectants, biocides, heavy metals and improper chemical sterilization that contribute to the development of AMR. Furthermore, it encompasses the mechanisms like co-resistance and co-selection, horizontal gene transfer, changes in the composition and permeability of cell membrane, efflux pumps, transposons, biofilm formation and enzymatic degradation of antimicrobial chemicals which underlie the development of resistance to various non-antibiotic antimicrobial agents. In addition, the review addresses the resistance-associated changes that develops in microorganisms due to these agents, which ultimately contribute to the development of resistance to antibiotics. In order to prevent the indiscriminate use of chemical substances and create novel therapeutic agents to halt resistance development, a more holistic scientific approach might provide diversified views on crucial factors contributing to the persistence and spread of AMR. The review illustrates the common and less explored mechanisms contributing directly or indirectly to the development of AMR by non-antimicrobial agents that are commonly used.

Biosynthesis of silver nanoparticles using nitrate reductase from Aspergillus terreus N4 and their potential use as a non-alcoholic disinfectant.

Green technology has been developed for the quick production of stabilized silver nanoparticles (AgNPs), with the assistance of nitrate reductase from an isolated culture of Aspergillus terreus N4. The organism's intracellular and periplasmic fractions contained nitrate reductase, with the former demonstrating the highest activity of 0.20 IU/g of mycelium. When the fungus was cultivated in a medium comprising 1.056% glucose, 1.836% peptone, 0.3386% yeast extract, and 0.025% KNO3, the greatest nitrate reductase productivity of 0.3268 IU/g was achieved. Statistical modeling via response surface methodology was used to optimize the enzyme production. The periplasmic and intracellular enzyme fractions were found to convert Ag+ to Ag0, initiating synthesis within 20 min, with predominant nanoparticle sizes between 25 and 30 nm. By normalizing the effects of temperature, pH, AgNO3 concentration, and mycelium age with a variable shaking period for enzyme release, the production of AgNPs with the periplasmic fraction was optimized. The synthesis of nanoparticles occurred at temperatures of 30, 40, and 50 °C, with the highest yield observed at 40 and 50 °C during shorter incubation periods. Similarly, the nanoparticles were synthesized at pH levels of 7.0, 8.0, and 9.0, with the greatest production observed at pH 8.0 and 9.0 at lower incubation periods. The antimicrobial activity of AgNPs was demonstrated against common foodborne pathogens, including Staphylococcus aureus and Salmonella typhimurium, indicating their potential as non-alcoholic disinfectants.

An Effective Sanitizer for Fresh Produce Production: In Situ Plasma-Activated Water Treatment Inactivates Pathogenic Bacteria and Maintains the Quality of Cucurbit Fruit.

The effect of plasma-activated water (PAW) generated with a dielectric barrier discharge diffusor (DBDD) system on microbial load and organoleptic quality of cucamelons was investigated and compared to the established sanitizer, sodium hypochlorite (NaOCl). Pathogenic serotypes of Escherichia coli, Salmonella enterica, and Listeria monocytogenes were inoculated onto the surface of cucamelons (6.5 log CFU g-1) and into the wash water (6 log CFU mL-1). PAW treatment involved 2 min in situ with water activated at 1,500 Hz and 120 V and air as the feed gas; NaOCl treatment was a wash with 100 ppm total chlorine; control treatment was a wash with tap water. PAW treatment produced a 3-log CFU g-1 reduction of pathogens on the cucamelon surface without negatively impacting quality or shelf life. NaOCl treatment reduced the pathogenic bacteria on the cucamelon surface by 3 to 4 log CFU g-1; however, this treatment also reduced fruit shelf life and quality. Both systems reduced 6-log CFU mL-1 pathogens in the wash water to below detectable limits. The critical role of superoxide anion radical (·O2-) in the antimicrobial power of DBDD-PAW was demonstrated through a Tiron scavenger assay, and chemistry modeling confirmed that ·O2- generation readily occurs in DBDD-PAW generated with the employed settings. Modeling of the physical forces produced during plasma treatment showed that bacteria likely experience strong local electric fields and polarization. We hypothesize that these physical effects synergize with reactive chemical species to produce the acute antimicrobial activity seen with the in situ PAW system. IMPORTANCE Plasma-activated water (PAW) is an emerging sanitizer in the fresh food industry, where food safety must be achieved without a thermal kill step. Here, we demonstrate PAW generated in situ to be a competitive sanitizer technology, providing a significant reduction of pathogenic and spoilage microorganisms while maintaining the quality and shelf life of the produce item. Our experimental results are supported by modeling of the plasma chemistry and applied physical forces, which show that the system can generate highly reactive ·O2- and strong electric fields that combine to produce potent antimicrobial power. In situ PAW has promise in industrial applications as it requires only low power (12 W), tap water, and air. Moreover, it does not produce toxic by-products or hazardous effluent waste, making it a sustainable solution for fresh food safety.

Caries affected disinfection using Phycocyanin activated by PDT, Holy Basil, and Ti-sapphire laser on adhesive bond strength, microleakage, and bond failure.

AIM: To investigate the effect of different cavity disinfectants, Phycocyanin (PC), Ocimum Sanctum (OS), and Ti Sapphire Laser, on the bond integrity and microleakage of resin restorations. MATERIAL AND METHOD: 60 human mandibular molars were extracted and prepared based on ICDAS scores of 4 and 5. To obtain the CAD surface, a visual examination was supported by tactile sensation and a dye for caries detection. Samples were randomly allocated into 4 groups based on cavity disinfectants applied (n = 15). Group 1: Specimens disinfected with CHX, Group 2: Specimens disinfected with Ti sapphire laser, Group 3: Specimens disinfected with Phycocyanin activated by Photodynamic therapy, and Group 4: Specimens disinfected with OS. Following the disinfection of the CAD surfaces, composite bulk-fill restorative material was bonded to each specimen and all samples were subjected to thermocycling. Ten samples from each group underwent SBS testing performed on a universal testing machine. Five samples were subjected to a microleakage analysis. RESULT: The maximum microleakage scores were displayed by Group 3: PC (0.521 nm) treated specimens. Whereas, and minimum microleakage was exhibited by Group 4: OS (0.471 nm). Group 4: OS (23.06±0.21 MPa) treated group displayed the maximum bond scores of resin adhesive to the CAD surface. However, Group 3: PC (21.67±0.24 MPa) treated specimens exhibited the lowest bond scores. Failure mode analysis revealed that among all the investigated groups the predominant type of failure was cohesive failure i.e., Group 1 (80%), Group 2 (80%), Group 3 (70%), and Group 4 (90%). CONCLUSION: Ocimum Sanctum, Phycocyanin activated by Photodynamic therapy, and Ti-sapphire laser for disinfection of caries-affected dentin have shown promise in terms of improved bond strength and reduced microleakage.

Eco-friendly and effective antimicrobial Melaleuca alternifolia essential oil Pickering emulsions stabilized with cellulose nanofibrils against bacteria and SARS-CoV-2.

Melaleuca alternifolia essential oil (MaEO) is a green antimicrobial agent suitable for confection eco-friendly disinfectants to substitute conventional chemical disinfectants commonly formulated with toxic substances that cause dangerous environmental impacts. In this contribution, MaEO-in-water Pickering emulsions were successfully stabilized with cellulose nanofibrils (CNFs) by a simple mixing procedure. MaEO and the emulsions presented antimicrobial activities against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Moreover, MaEO deactivated the SARS-CoV-2 virions immediately. FT-Raman and FTIR spectroscopies indicate that the CNF stabilizes the MaEO droplets in water by the dipole-induced-dipole interactions and hydrogen bonds. The factorial design of experiments (DoE) indicates that CNF content and mixing time have significant effects on preventing the MaEO droplets' coalescence during 30-day shelf life. The bacteria inhibition zone assays show that the most stable emulsions showed antimicrobial activity comparable to commercial disinfectant agents such as hypochlorite. The MaEO/water stabilized-CNF emulsion is a promissory natural disinfectant with antibacterial activity against these bacteria strains, including the capability to damage the spike proteins at the SARS-CoV-2 particle surface after 15 min of direct contact when the MaEO concentration is 30 % v/v.

Efficacy of methylene blue and curcumin mediated antimicrobial photodynamic therapy in the treatment of indirect pulp capping in permanent molar teeth.

PURPOSE: This study aimed to evaluate the adhesive bond strength and antibacterial efficacy of methylene blue (MB)-mediated antimicrobial photodynamic therapy (aPDT) and curcumin (CUR)-mediated aPDT versus the conventional disinfectants, such as chlorhexidine gluconate (CHX) gel and sodium hypochlorite (NaOCl), for indirect pulp capping (IPC) treatment of permanent molars. METHODS: One Hundred grossly carious human permanent molars were collected through non-traumatic extraction. All specimens were embedded in polyvinyl cross-sections to the cemento-enamel junction. The cavity preparation was conducted by grinding the samples using silicon carbide discs. After culturing Streptococcus mutans (S. mutans), a 10 µL of S. mutans suspension (106 colony forming units/mL) was transferred in each tooth cavity and anaerobically incubated for 48 h at 37 °C. All specimens were randomly divided into 5 groups: Group-I: samples treated IPC; Group-II: samples treated with 2% CHX gel; Group-III: samples treated with 6% NaOCl; Group-IV: irradiation of prepared cavity with MB-mediated aPDT; and Group-V: irradiation of prepared cavity with CUR-mediated aPDT. After disinfection methods, the universal adhesive was used, and all specimens were restored using giomer. Eventually, confocal laser scanning microscopy, shear bond strength (SBS), micro-tensile bond strength (µTBS), four-point bending strength (4P-BS) analyses were performed, and the data were analyzed statistically. RESULTS: At baseline, the highest SBS (48.8 ± 6.5 MPa), µTBS (54.3 ± 3.9 MPa), and 4P-BS (123 ± 32 MPa) scores were demonstrated by the samples treated with MB-mediated aPDT. However, after 12 months of storage, the highest SBS (42.3 ± 3.9 MPa) and µTBS (45.2 ± 6.6 MPa) scores were shown by samples treated with MB-mediated aPDT, while CUR-mediated aPDT treated samples demonstrated the highest 4P-BS scores (70 ± 18 MPa). Moreover, the highest antibacterial activity against S. mutans was shown by the samples treated with MB-mediated aPDT. CONCLUSIONS: The application of aPDT, especially MB-mediated, demonstrated superior SBS, µTBS, and 4P-BS values as well as antibacterial activity against S. mutans as compared to 2% CHX gel and 6% NaOCl as cavity disinfectants for IPC treatment of permanent molars.

In vitro Evaluation the Efficacy of Some New Plant Extracts and Biocides on the Viability of Acanthamoeba castellanii.

The purpose of this study was to assess the efficacy of certain plant extracts and to compare them with current biocides on the viability of Acanthamoeba castellanii cysts and trophozoites in vitro. Amoebicidal and cysticidal assays were performed against both trophozoites and cysts of Acanthamoeba castellanii (ATCC 50370). Ten plant extracts were evaluated alongside the current agents included polyhexamethylene biguanide (PHMB), octenidine and chlorhexidine digluconate. A. castellanii (ATCC 50370) was treated to serial two-fold dilutions of the test compounds and extracts in microtitre plate wells to investigate the effect on trophozoites and cysts of A. castellanii (ATCC 50370). Furthermore, the toxicity of each of the test compounds and extracts were assessed towards a mammalian cell line. Minimum trophozoite inhibitory concentration (MTIC), minimum trophozoite amoebicidal concentration (MTAC), and minimum cysticidal concentration (MCC) were used to establish A. castellanii (ATCC 50370) in vitro sensitivity. The findings of this research revealed that the biguanides PHMB, chlorhexidine, and octenidine all had excellent effectiveness against trophozoites and cysts of A. castellanii (ATCC 50370). The plant extracts testing results showed that, great activity against trophozoites and cysts ofA. castellanii (ATCC 50370) at lower concentrations. This is the first study to demonstrate that the Proskia plant extract had the lowest MCC value, which was 3.9 µg/mL. The time kill experiment confirmed this finding, as this extract reduced cysts of A. castellanii (ATCC 50370) by more than 3-log at 6 hour and by 4-log after 24 hour. The anti-amoebic efficacy of new plant extracts on the viability of A. castellanii (ATCC 50370) cysts and trophozoites was comparable to existing biocide treatments and was not toxic when tested on a mammalian cell line. This could be a promising novel Acanthamoeba treatment by using the tested plant extracts as a monotherapy against trophozoites and cysts.

Decontamination of lithium disilicate ceramics using various photosensitizers, herbal and chemical disinfectants, and the effect of surface conditioners on bond strength values.

AIM: To assess and compare the antimicrobial efficacy of disinfectants on lithium disilicate ceramic (LDC) used in dental applications and shear bond strength (SBS) of LDC after using different conditioners hydrofluoric acid (HF), self-etching ceramic primers (SECP) and Neodymium-doped yttrium orthovanadate (Nd: YVO4). MATERIALS AND METHODS: One hundred and twenty LDC discs were fabricated by auto-polymerizing acrylic resin using the lost wax technique. S. aureus, S. mutans, and C. albican were inoculated on thirty discs (n = 30 each). Each group was further divided into three subgroups based on different disinfecting agents used (n = 30) Group 1: Garlic extract, Group 2: Rose Bengal (RB) activated by PDT, and Group 3: Sodium hypochlorite (NaOCl). An assessment of the survival rate of microorganisms was performed. The remaining thirty samples were surface treated using three different LDC surface conditioners (n = 10) Group 1: HF + Silane (S), group 2: SECP, and Group 3: Nd: YVO4 laser+S. SBS and failure mode analysis were performed using a universal testing machine and stereomicroscope at 40x magnification, The statistical analysis was conducted using one-way ANOVA and Post Hoc Tukey test. RESULTS: Garlic extract, RB, and 2% NaOCl sample displayed comparable outcomes of antimicrobial potency against C. albicans, S aureus, and S. mutans (p > 0.05). Furthermore, SBS analysis showed HF+S, SECP, and Nd: YVO4+S exhibited comparable outcomes of bond strength (p > 0.05). CONCLUSION: Garlic extract and Rose bengal activated by PDT can be contemplated as alternatives to the chemical agent NaOCl used for LDC disinfection. Similarly, SECP and Nd: YVO4 possess the potential to be used for the surface conditioning of LDC to improve the bond integrity with resin cement.

Antimicrobial and antibiofilm potentiation by a triple combination of dual biocides and a phytochemical with complementary activity.

The failure of current sanitation practices requires the development of effective solutions for microbial control. Although combinations using antibiotics have been extensively studied to look for additive/synergistic effects, biocide combinations are still underexplored. This study aims to evaluate the antimicrobial effectiveness of dual biocide and triple biocide/phytochemical combinations, where phytochemicals are used as quorum sensing (QS) inhibitors. The biocides selected were benzalkonium chloride (BAC) and peracetic acid (PAA) - as commonly used biocides, and glycolic acid (GA) and glyoxal (GO) - as alternative and sustainable biocides. Curcumin (CUR) and 10-undecenoic acid (UA) were the phytochemicals selected, based on their QS inhibition properties. A checkerboard assay was used for the screening of chemical interactions based on the cell growth inhibitory effects against Bacilluscereus and Pseudomonasfluorescens. It was observed that dual biocide combinations resulted in indifference, except the PAA + GA combination, which had a potential additive effect. PAA + GA + CUR and PAA + GA + UA combinations also triggered additive effects. The antimicrobial effects of the combinations were further evaluated on the inactivation of planktonic and biofilm cells after 30 min of exposure. These experiments corroborated the checkerboard results, in which PAA + GA was the most effective combination against planktonic cells (additive/synergistic effects). The antimicrobial effects of triple combinations were species- and biocide-specific. While CUR only potentiate the antimicrobial activity of GA against B.cereus, GA + UA and PAA + GA + UA combinations promoted additional antimicrobial effects against both bacteria. Biofilms were found to be highly tolerant, with modest antimicrobial effects being observed for all the combinations tested. However, this study demonstrated that low doses of biocides can be effective in bacterial control when combining biocides with a QS inhibitor, in particular, the combination of the phytochemical UA (as a QS inhibitor) with GA and PAA.

An Antimicrobial Fabric Using Nano-Herbal Encapsulation of Essential Oils.

Lab coats are widely used in biohazard laboratories and healthcare facilities as protective garments to prevent direct exposure to pathogens, spills, and burns. These cotton-based protective coats provide ideal conditions for microbial growth and attachment sites due to their porous nature, moisture-holding capacity, and retention of warmth from the user's body. Several studies have demonstrated the survival of pathogenic bacteria on hospital garments and lab coats, acting as vectors of microbial transmission. A common approach to fix these problems is the application of antimicrobial agents in textile finishing, but concerns have been raised due to the toxicity and environmental effects of many synthetic chemicals. The ongoing pandemic has also opened a window for the investigation of effective antimicrobials and eco-friendly and toxic-free formulations. This study uses two natural bioactive compounds, carvacrol and thymol, encapsulated in chitosan nanoparticles, which guarantee effective protection against four human pathogens with up to a 4-log reduction (99.99%). These pathogens are frequently detected in lab coats used in biohazard laboratories. The treated fabrics also resisted up to 10 wash cycles with 90% microbial reduction, which is sufficient for the intended use. We made modifications to the existing standard fabric tests to better represent the typical scenarios of lab coat usage. These refinements allow for a more accurate evaluation of the effectiveness of antimicrobial lab coats and for the simulation of the fate of any accidental microbial spills that must be neutralized within a short time. Further studies are recommended to investigate the accumulation of pathogens over time on antimicrobial lab coats compared to regular protective coats.