CFU Reduction Research Articles

Identification of genes associated with persistence in Mycobacterium smegmatis.

The prevalence of bacterial persisters is related to their phenotypic diversity and is responsible for the relapse of chronic infections. Tolerance to antibiotic therapy is the hallmark of bacterial persistence. In this study, we have screened a transposon library of Mycobacterium smegmatis mc2155 strain using antibiotic tolerance, survival in mouse macrophages, and biofilm-forming ability of the mutants. Out of 10 thousand clones screened, we selected ten mutants defective in all the three phenotypes. Six mutants showed significantly lower persister abundance under different stress conditions. Insertions in three genes belonging to the pathways of oxidative phosphorylation msmeg_3233 (cydA), biotin metabolism msmeg_3194 (bioB), and oxidative metabolism msmeg_0719, a flavoprotein monooxygenase, significantly reduced the number of live cells, suggesting their role in pathways promoting long-term survival. Another group that displayed a moderate reduction in CFU included a glycosyltransferase, msmeg_0392, a hydrogenase subunit, msmeg_2263 (hybC), and a DNA binding protein, msmeg_2211. The study has revealed potential candidates likely to facilitate the long-term survival of M. smegmatis. The findings offer new targets to develop antibiotics against persisters. Further, investigating the corresponding genes in M. tuberculosis may provide valuable leads in improving the treatment of chronic and persistent tuberculosis infections.

The Antibacterial Properties of a Silver Multilayer Coating for the Prevention of Bacterial Biofilm Formation on Orthopedic Implants—An In Vitro Study

The prevention of biofilm formation on orthopedic implants is essential, as biofilms are the main challenge in the effective treatment of periprosthetic joint infection (PJI). A silver multilayer (SML) coating was developed to prevent biofilm formation on the implant surface. Previous studies have already demonstrated its antibacterial properties without cytotoxic effects. However, the coating has not been previously tested when applied to common titanium surfaces used in total joint arthroplasty implants. These surfaces often have increased roughness and porosity in the case of cementless implants, which can alter the antibacterial effect of the coating. In this study, we assessed the antibacterial and anti-biofilm properties of the SML coating on corundum-blasted and plasma-sprayed microporous-coated titanium alloy surfaces, using S. aureus, S. epidermidis, and E. coli. An antibacterial activity test following the principles of ISO 22196, ASTM E2180-18, and JIS Z 2801 standards was performed, as well as a biofilm proliferation assay investigating bacterial adhesion and biofilm formation. The SML coating exhibited strong antibacterial effects for all bacterial strains. After 24 h biofilm culture, a >4-log reduction in CFU was induced by the SML coating for S. epidermidis and E. coli on the corundum-blasted and plasma-sprayed microporous-coated titanium surfaces, respectively, when compared to the uncoated surfaces. The coating showed bactericidal properties against Gram-positive bacteria on the corundum-blasted discs. The SML coating on two common titanium surfaces demonstrates significant potential as an effective strategy in combating PJI across a wide range of orthopedic implants.

Lactoferrin/pectin nanocomplex encapsulating ciprofloxacin and naringin as a lung targeting antibacterial nanoplatform with oxidative stress alleviating effect

Pseudomonas aeruginosa is an opportunistic Gram-negative bacterium with adaptive metabolic abilities. It can cause hospital-acquired infections with significant mortality rates, particularly in people with already existing medical conditions. Its ability to develop resistance to common antibiotics makes managing this type of infections very challenging. Furthermore, oxidative stress is a common consequence of bacterial infection and antibiotic therapy, due to formation of reactive oxygen species (ROS) during their mode of action. In this study we aimed to alleviate oxidative stress and enhance the antibacterial efficacy of ciprofloxacin (CPR) antibiotic by its co-encapsulation with naringin (NAR) within a polyelectrolyte complex (PEX). The PEX comprised of polycationic lactoferrin (LF) and polyanionic pectin (PEC). CPR/NAR-loaded PEX exhibited spherical shape with particle size of 237 ± 3.5 nm, negatively charged zeta potential (−23 ± 2.2 mV) and EE% of 61.2 ± 4.9 for CPR and 76.2 ± 3.4 % for NAR. The LF/PEC complex showed prolonged sequential release profile of CPR to limit bacterial expansion, followed by slow liberation of NAR, which mitigates excess ROS produced by CPR's mechanism of action without affecting its efficacy. Interestingly, this PEX demonstrated good hemocompatibility with no significant in vivo toxicity regarding hepatic and renal functions. In addition, infected mice administrated this nanoplatform intravenously exhibited significant CFU reduction in the lungs and kidneys, along with reduced immunoreactivity against myeloperoxidase. Moreover, this PEX was found to reduce the lungs´ oxidative stress via increasing both glutathione (GSH) and catalase (CAT) levels while lowering malondialdehyde (MDA). In conclusion, CPR/NAR-loaded PEX can offer a promising targeted lung delivery strategy while enhancing the therapeutic outcomes of CPR with reduced oxidative stress.

Cold plasma treatment for fungal keratitis

Aims/Purpose: Fungal keratitis is serious ocular infection caused by any of the fungi species. It is treated with antifungal medications, in worst scenario with cornea transplantation. The therapy is still challenging due to poor drug penetration into the cornea. Cold plasma, produced by ionization of argon gas, contains especially reactive species but also UV radiation which damage microorganisms. The aim of this study is to determine the effect of cold plasma on human corneal epithelial cells (HCE), corneal tissue and multiple pathogen microorganisms to assess the opportunity of cold plasma treatment for fungal keratitis.Methods: The effect of cold plasma on HCE was analysed by the light microscopy, Live/Dead assay, metabolic activity assay, and immunohistochemistry. Disinfecting potential was analysed by plating prevalent yeasts (Candida albicans, C. krusei, C. parapsilosis, C. glabrata) on agar plates and treated with cold plasma. Plasma treatment of infected human donor corneas with C. albicans was determined by measurement of O.D. of liquid culture.Results: The treatment of HCE by cold plasma led to the change of the morphology, significantly lower viability, metabolic activity and proliferation of the cells. Yeast strains were significantly eradicated completely after 5 min of cold plasma treatment (p ≤ 0.001). Cold plasma therapy of the infected human donor corneas showed the decrease of the infection in all tested time intervals with statistical significance (p ≤ 0.01, p < 0.05 and p ≤ 0.001 respectively for 1, 2 and 5 min treatment).Conclusions: Cold plasma treatment showed negative impact on the culture of HCE. The analysis of its effect on the whole corneal tissue is in progress. On the contrary, a significant reduction of CFU was observed in all examined Candida spp. and significant decrease of infection was determined in infected corneas. Therefore, the cold plasma technology showed a potential to be an effective treatment for fungal keratitis.

Maltodextrin-binding protein as a key factor in Cronobacter sakazakii survival under desiccation stress

Cronobacter sakazakii (C. sakazakii) is a notorious pathogen responsible for infections in infants and newborns, often transmitted through contaminated infant formula. Despite the use of traditional pasteurization methods, which can reduce microbial contamination, there remains a significant risk of pathogenic C. sakazakii surviving due to its exceptional stress tolerance. In our study, we employed a comparative proteomic approach by comparing wild-type strains with gene knockout strains to identify the essential genes crucial for the successful survival of C. sakazakii during desiccation. Our investigation revealed the significance of envZ-ompR, recA, and flhD gene cassettes in contributing to desiccation tolerance in C. sakazakii. Furthermore, through our comparative proteomic profiling, we identified the maltodextrin-binding protein encoded by ESA_03421 as a potential factor influencing dry tolerance. This protein is regulated by EnvZ-OmpR, RecA, and FlhD. Notably, the knockout of ESA_03421 resulted in a 150% greater reduction in Log CFU compared to the wild-type C. sakazakii. Overall, our findings offer valuable insights into the mechanisms underlying C. sakazakii desiccation tolerance and provide potential targets for the development of new antimicrobial strategies aimed at reducing the risk of infections in infants and newborns.

Comparative evaluation of plaque removal efficacy and quantitative analysis of <em>Streptococcus mutans</em> in saliva after using nylon and charcoal bristles toothbrushes in children: A clinico-microbiological study

Background: Dental biofilms are the primary aetiologic factors in the 2 most prevalent oral diseases, dental caries and periodontal disease. Among all oral hygiene methods available, mechanical plaque removal with a toothbrush is the primary mode of maintaining good oral hygiene.Objectives: Comparative evaluation of plaque removal efficacy and quantitative analysis of Streptococcus mutans in saliva after using nylon and charcoal bristles toothbrushes in children.Method: Forty healthy children aged 8-10 years having decayed-missing-filled-tooth (DMFT) score less than 5 were randomly allocated into two groups, one using charcoal bristles and the other using nylon bristles toothbrush. Loe & Silness Plaque Index was recorded along with saliva sample collection for Streptococcus mutans count before and after using the respective toothbrushes for 1 week.Results: A significant reduction in plaque index was observed in each group with a non-significant reduction in Streptococcus mutans CFU. However, the comparison between the two groups was not statistically significant.Conclusions: This randomised, parallel, singleblinded clinical study demonstrated that both nylon and charcoal bristles toothbrushes significantly enhanced plaque control but there was no significant difference in the two methods. There was no significant reduction in Streptococcus mutans CFU.

2532. Pharmacokinetic-Pharmacodynamic Analyses for Ceftobiprole Efficacy Based on Phase 3 Data from Patients with Staphylococcus aureus Bacteremia

2532. Pharmacokinetic-Pharmacodynamic Analyses for Ceftobiprole Efficacy Based on Phase 3 Data from Patients with <i>Staphylococcus aureus</i> Bacteremia

Quaternary ammonium-based coating of textiles is effective against bacteria and viruses with a low risk to human health

While the global healthcare system is slowly recovering from the COVID-19 pandemic, new multi-drug-resistant pathogens are emerging as the next threat. To tackle these challenges there is a need for safe and sustainable antiviral and antibacterial functionalized materials. Here we develop an 'easy-to-apply' procedure for the surface functionalization of textiles, rendering them antiviral and antibacterial and assessing the performance of these textiles. A metal-free quaternary ammonium-based coating was applied homogeneously and non-covalently to hospital curtains. Abrasion, durability testing, and aging resulted in little change in the performance of the treated textile. Additionally, qualitative and quantitative antibacterial assays on Staphylococcus aureus, Pseudomonas aeruginosa, and Acinetobacter baumanii revealed excellent antibacterial activity with a CFU reduction of 98–100% within only 4 h of exposure. The treated curtain was aged 6 months before testing. Similarly, the antiviral activity tested according to ISO-18184 with murine hepatitis virus (MHV) showed > 99% viral reduction with the functionalized curtain. Also, the released active compounds of the coating 24 ± 5 µg mL−1 revealed no acute in vitro skin toxicity (IC50: 95 µg mL−1) and skin sensitization. This study emphasizes the potential of safe and sustainable metal-free textile coatings for the rapid antiviral and antibacterial functionalization of textiles.

Glycogen plays a key role in survival of Salmonella Typhimurium on dry surfaces and in low-moisture foods

Salmonella enterica is known to survive in desiccate environments and is often associated with low-moisture foods (LMFs). In this work, S. Typhimurium ATCC 14028 was found to survive better by achieving the least reductions (3.17 ± 0.20 Log CFU reduction) compared to S. Tennessee ATCC 10722 (3.82 ± 0.13 Log CFU reduction) and S. Newport ATCC 6962 (6.03 ± 0.36 Log CFU reduction) after 30 days on surfaces with a relative humidity of 49% at ambient temperature. A metabolomic analysis revealed that S. Typhimurium was still active in energy metabolism after 24 h in the desiccate environment and glycogen, an energy reserve, was drastically reduced. We followed up on the glycogen levels over 30 days and found indeed a sharp decline on the first day. However, the glycogens detected on day 7 were significantly higher (P < 0.05) and thereafter remained stable above the original levels until day 30. The expression levels of both glycogen anabolism- and catabolism-related genes (csrA, glgA, glgC, glgX) were significantly up-regulated at all tested points (P < 0.05). The glgA and glgC insertion mutants displayed weaker survivability on both dry surfaces and in representative LMFs (flour and milk powder) compared to the wild-type strain. This work highlights the role of glycogen during different periods of desiccation, which may bring novel insight into mitigating Salmonella by disrupting glycogen metabolism.

Delineating the functional role of the PPE50 (Rv3135) - PPE51 (Rv3136) gene cluster in the pathophysiology of Mycobacterium tuberculosis

The extraordinary success of Mycobacterium tuberculosis (M. tb) has been attributed to its ability to modulate host immune responses, and its genome encodes multiple immunomodulatory factors, including several proteins of the multigenic PE_PPE family. To understand its role in M. tb pathophysiology we have characterised the PPE50 (Rv3135)-PPE51 (Rv3136) gene cluster, one of nine PPE-PPE clusters in the genome. We demonstrate here that this cluster is operonic, and that PPE50 and PPE51 interact - the first demonstration of PPE-PPE interaction. THP-1 macrophages infected with recombinant M. smegmatis strains expressing PPE50 and PPE51 showed less intracellular viability than the control, which correlated with an increase in transcript levels of iNOS2. Infected macrophages also exhibited an upregulation in levels of IL-10, indicating an immunomodulatory role for these proteins. Using pull-downs and signalling assays, we identified TLR1 to be the cognate receptor for PPE50 - all the phenotypes observed on infection of THP-1 macrophages were reversed on pre-treatment with an anti-TLR1 antibody, validating the functional outcome of PPE50-TLR1 interaction. Our data reveals a TLR1 dependent role for the PPE50-PPE51 cluster in promoting bacillary persistence, via CFU reduction and concomitant upregulation of the anti-inflammatory response - a two-pronged strategy to circumvent host immune surveillance.

Green synthesis of silver nanomaterials and evaluation of their antibacterial and antioxidant effectiveness in chicken meat

Nanomaterials, chiefly silver nanoparticles (AgNP), are widely used in many commercial products, including medical commodities, food packaging and cosmetics. The goal of this research was to establish a cost-effective and environmentally safe approach to synthesize AgNP using turmeric powder. The reduction of silver ions resulted in an alteration of the turmeric extract color from yellow to brown after 24 h of reaction. The characterization of AgNP was accomplished by UV–vis spectroscopy, energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). The prominent peak of AgNP colloid in a UV–vis spectrum appears at 444 nm. EDS mapping showed a potent signal of the silver element. According to TEM, most of the synthesized AgNP was spherical with an average size of 23 ± 0.49 nm. Moreover, FTIR test proved the presence of organic constituents in the AgNP colloid. The green AgNP exhibited significant (P ≤ 0.05) antibacterial activities with a 2-log CFU reduction of a Salmonella Typhimurium and Salmonella Enteritidis cocktail in chicken meat after a 1-day direct exposure to 6, 12, and 18 μg/mL of AgNP. The phytoconstituents on the surface of the AgNP exhibited good antioxidant activities by scavenging DPPH and ABTS radicals. Moreover, the nanoparticles had a higher antioxidant capacity compared to standard ascorbic acid solution, especially at 12 and 18 μg/mL of AgNP concentrations. These outcomes indicate that AgNP coated with phyto-constituents possess powerful bioactivities by inhibiting the growth of food pathogenic bacteria and, simultaneously, conferring antioxidant capability.

Description and results of a new method for assessing real-life performance of a UV-C disinfection robot

Due to the disadvantages of manual disinfection of patient rooms, mobile disinfection robots using ultraviolet C (UV-C) radiation are increasingly being used. Assessing their in situ effectiveness remains challenging. This study describes a new method to prove adequate in situ disinfection (≥5-log reduction in bacterial load), and uses this method to assess the efficacy of a mobile disinfection robot using UV-C radiation. Agar plates serving as proxies for smooth surfaces in patient rooms were inoculated with bacterial suspension and placed on various surfaces in a patient room. After irradiation by an automated mobile UV-C robot, reduction in colony growth was determined by comparing the irradiated plates to a reference series of non-irradiated plates, enabling the evaluation of whether an adequate reduction in colony-forming units (CFU's) of ≥5-log was reached on these irradiated surfaces. The new technique described here proved a successful method for demonstrating an in situ ≥5-log reduction in CFU's for five different bacterial pathogens. Of the 32 plates placed on UV-accessible surfaces, 31 showed an adequate reduction in CFU's of ≥5-log. One plate could not be assessed. Inoculated agar plates placed in patient rooms before irradiation and subsequently compared to a reference series can be used to assess in situ efficacy of mobile disinfection robots using UV-C radiation. Our findings support the idea that UV-C robots, used adjunctively to conventional manual washing and disinfection, may achieve adequate bacterial load reduction on UV-accessible smooth surfaces in patient rooms for a selected subset of pathogens.

Synergistic effect of chlorhexidine and azoles on candida biofilm on titanium surface.

Candida infections of orthopedic implants are one of the most detrimental orthopedic implant-related complications with unsuccessful treatment and a poor prognosis. Most orthopedic Candida infections form biofilms and have resistance to the commonly used antifungal agents. This study aimed to develop a novel combination of normally prescribed drugs against Candida biofilm on orthopedic implants. We cultured 26 clinical isolates of Candida strains to form biofilm without titanium sheets or on titanium sheets, which are the most commonly used materials for permanent or orthopedic implants. The checkerboard method was used to evaluate the synergistic effects of chlorhexidine (CHL) and azoles on these Candida biofilms. For the evaluation of synergistic effects, we constructed the cell viability assay by fluorescence staining and CFU reduction hot map of Candida. Twenty-six clinical isolates of Candida strains formed biofilm in 96-well plates without titanium sheets, and we selected 9 of them to form biofilm on titanium sheets in 24-well plates. In Candida biofilm formed in 96-wells, the synergistic rates of CHL with fluconazole, itraconazole, and voriconazole were 61% (16/26), 65% (17/26), and 23% (6/26), respectively. When compared to the blank control group, CHL monotherapy significantly inhibited biofilm formation on titanium sheets (P < 0.05). We demonstrated 100% synergistic rates of the CHL and fluconazole combination against Candida biofilm formation on titanium sheets, and the minimum inhibitory concentration of CHL and FLU decreased four- to eight-fold. We concluded that CHL combined with azoles inhibited the Candida biofilm formation 96-wells or on titanium sheets and has the potential to control the infections of orthopedic implants.

Eco-Friendly Capsaicin-Containing Water-Based Antifouling Coatings for Marine Aquaculture

Natural antifoulants have received significant interest in the search for non- or less-toxic antifouling coating systems for marine structures. Capsaicin, a natural compound that can be found in chili peppers, is known as an environmentally friendly antifouling agent with an excellent performance and a low environmental impact. However, controlling its release from the coating matrix is still an issue to be solved. With the aim of developing an eco-friendly antifouling system with prolonged long-term activity, in this study, we incorporated capsaicin in combination with dichlofluanid into water-based acrylic coating formulations. The antifouling activity of the resulting coatings was studied by examining the survival behavior of a Gram-negative marine bacterium Aeromonas Salmonoid ATCC 33658, and the release rate of capsaicin from the paint matrix was also assessed. The combination of 0.75 wt.% capsaicin and 0.75 wt.% dichlofluanid into the same matrix showed an antibacterial performance of up to 99.9% cfu reduction with an antibacterial value R 2.5–3 times higher than those obtained with the single biocides at 1.5 wt.%. The association between the two organic biocides created a synergistic effect on the antifouling performance, further resulting in a prolonged activity.

Evaluation of omadacycline against intracellular Mycobacterium abscessus in an infection model in human macrophages.

Omadacycline is an aminomethylcycline antibiotic in the tetracycline class that was approved by the US FDA in 2018 for the treatment of community-acquired bacterial pneumonia and acute bacterial skin and skin structure infections. It is available in both IV and oral formulations. Omadacycline has broad-spectrum in vitro activity and clinical efficacy against infections caused by Gram-positive and Gram-negative pathogens. Omadacycline is being evaluated in a 3 month placebo-controlled Phase 2 clinical trial of oral omadacycline versus placebo in adults with non-tuberculous mycobacteria (NTM) pulmonary disease caused by Mycobacterium abscessus (NCT04922554). To determine if omadacycline has intracellular antimicrobial activity against NTM, bacteria that can cause chronic lung disease, in an ex vivo model of intracellular infection. Two strains of M. abscessus were used to infect THP-1 macrophages. Intracellular M. abscessus was then challenged with omadacycline and control antibiotics at multiples of the MIC over time to evaluate intracellular killing. At 16 × the MIC at 72 h, omadacycline treatment of intracellular NTM yielded a log10 reduction in cfu of 1.1 (91.74% reduction in cfu) and 1.6 (97.65% reduction in cfu) consistent with killing observed with tigecycline, whereas amikacin and clarithromycin at 16 × the MIC did not show any reduction in cfu against the intracellular M. abscessus. Omadacycline displayed intracellular activity against M. abscessus within macrophages. The activity was similar to that of tigecycline; as expected, intracellular killing was not observed with clarithromycin and amikacin.

Plasma-activated water for inactivation of Salmonella Typhimurium avirulent surrogate: Applications in produce and shell egg and understanding the modes of action

Plasma-activated water (PAW) is gaining interest as a novel sanitizer for foods. However, the sanitizing efficacy of PAW varies under different conditions, and its modes of action and impacts on food quality need further investigation for it to be applied in the food industry. This study evaluated the inactivation efficacy of PAW against a Salmonella Typhimurium avirulent surrogate, investigated the underlying mechanisms, and assessed the impacts of PAW on the safety and quality of cherry tomatoes and shell eggs. PAW was effective in inactivating S. Typhimurium in a planktonic state (1.5–5.8 log CFU reduction in 2–5 min) and on the food surface (>5 log CFU reduction in 5 min). PAW prepared with deionized water vs. tap water did not differ significantly in sanitizing efficacy. Various reactive oxygen and nitrogen species (RONS) contributed to the antimicrobial property of PAW, with nitric oxide playing the most significant role. The acidic nature of PAW might synergistically affect bacteria by disrupting cell membrane and enhancing RONS permeation. PAW did not modify the visual appearance and internal pH of the treated foods. This study demonstrates that PAW has the potential to be applied as a novel sanitizer for fresh produce and egg washing.

Pharmacokinetic, Pharmacokinetic/Pharmacodynamic, and Safety Investigations of Lefamulin in Healthy Chinese Subjects.

This study aimed to explore the pharmacokinetics (PK) and safety of oral (PO) and intravenous (IV) lefamulin in healthy Chinese subjects and to evaluate the efficacy of the intravenous administration regimen using pharmacokinetic/pharmacodynamic (PK/PD) analysis. This study was a randomized, open-label, single- and multiple-dose, intravenous and oral administration study. PK parameters were calculated, and the probability of target attainment (PTA) and the cumulative fraction of response (CFR) after IV administration of lefamulin 150 mg 1 h q12 h were analyzed with Monte Carlo simulations. Lefamulin exhibited extensive distribution. The mean steady-state AUC0-24 h of 150 mg lefamulin IV and 600 mg lefamulin PO were 10.03 and 13.96 μg·h/mL, respectively. For Streptococcus pneumoniae and Staphylococcus aureus, based on the free-drug AUC over MIC ratio (fAUC/MIC) target of 1-log10 cfu reduction, the PK/PD breakpoints were 0.25 and 0.125 mg/L, respectively. The CFR was over 90% for both types of strains with 95% protein binding rate, suggesting that the regimen was microbiologically effective. Lefamulin was safe and well-tolerated. The PK of lefamulin in healthy Chinese subjects were consistent with that in foreign countries. Lefamulin demonstrated the microbiological effectiveness against Streptococcus pneumoniae and Staphylococcus aureus.

Storage-related stability and antimicrobial efficacy of bottled, neutral-pH Electrolysed Oxidising Water

ObjectivesDenture stomatitis is prevalent in older people and poses serious health risks. Ready-to-use (RTU) neutral-pH Electrolysed Oxidizing Water (EOW) is an effective environmental disinfectant used in residential care settings and geriatric wards. However, the influence of storage on stability and effectiveness for denture disinfection has not been established. This research investigated the storage-related stability and antimicrobial activity of RTU EOW, and its efficacy against Candida albicans biofilms formed on denture resin. MethodsThe pH, oxidation/reduction potential (mV), available chlorine content (mg/L) and [HOCl] (mM) of RTU EOW (Envirolyte, New Zealand) solutions (n = 22) were measured from bottle opening to 28 days following storage at 4 °C, room temperature (RT) or 37 °C. Staphylococcus aureus and C. albicans cells were incubated in 80% EOW for contact times (CTs) up to 15 min and colony-forming units (cfu) determined. Minimum inhibitory concentrations (MIC90 EOW-HOCl) after CTs up to five minutes were determined for S. aureus and C. albicans reference strains and clinical isolates. C. albicans-denture resin disc biofilms were assessed after a five-minute CT with undiluted EOW by XTT-metabolic activity assay. Results[HOCl] remained stable when RTU EOW was stored at 4 °C or RT for five months after manufacture. One-minute CT resulted in log10 cfu reductions of >6 for S. aureus and >5 for C. albicans. Mean MIC90 for five-minute CT was 37 µM (S. aureus) and 54 µM (C. albicans). Undiluted EOW reduced C. albicans biofilm metabolic activity by 86%. ConclusionsRTU neutral-pH EOW is stable over five-months storage and is an effective denture disinfectant. Clinical significanceThe efficacy of the RTU neutral EOW against C. albicans isolates and biofilms formed on denture resin surfaces supports its use as a denture disinfectant and can inform future research to assess its potential for preventing denture-related oral Candida infections in the older population, especially in resource-limited communities.

Dielectric and dynamic antibacterial investigations of organic–inorganic conductive membranes based on oxidized cellulose with BNKT nanoceramics

The development of eco-friendly materials for advanced applications is highly demanded. The current study focuses on the preparation of conductive membranes based on tricarboxylic cellulose (TCC) loaded with cubic bismuth sodium titanate (BNKT) nanoceramics. FTIR, SEM, and EDX analyses confirm the presence of loaded BNKT on the membranes. The electrical response of the cellulose/xBNKT (x = 5, 10, 15, and 20% wt/wt) membrane is investigated using impedance spectroscopy. The real part (Z′) and the imaginary part (Z″) of the complex impedance are studied as a function of frequency (4Hz ~ 8MHz) and temperature (20 ~ 160 °C) for the different compositions. Impedance and modulus studies reveal a Debye-type relaxation phenomenon. The dielectric studies manifest promising dielectric properties. The bactericidal performance of all nanomembranes is evaluated. The nanomembrane with 20% BNKT (C20) exhibits bactericidal activity against Gram-negative and Gram-positive bacteria, with 6 log CFU reductions observed after an exposure time of 180 min. Treatment with the C20 nanomembrane shows the highest amounts of protein efflux. The results indicate that the C20 nanomembrane layer eradicated all bacterial cells. The findings suggest that the C20 nanomembrane is recommended as an intelligent and innovative antibacterial nano-system for bio-applications.

Exploring Washing Procedures for Produce Brush Washer

Previous environmental monitoring projects in food production facilities have revealed inconsistencies in how produce brush washer machines are cleaned after use; thus, the study of effective sanitation procedures for these machines is needed. Four chlorine solution treatments (ranging from 25 to 200 ppm), as well as a water-only treatment, were tested for efficacy in reducing bacterial loads for a selected small brush washer machine. Results indicate that rinsing with the machine’s power and water alone, a frequent practice among some produce processors, yielded a reduction of 0.91–1.96 log CFU per brush roller in bacterial counts, which was not statistically significant (p > 0.05). However, the chlorine treatments were found to be effective in reducing bacterial loads significantly, with higher concentrations being the most effective. The 200 ppm and 100 ppm chlorine treatments yielded bacterial reductions of 4.08 and 3.95 log CFU per brush roller, respectively, leaving bacterial levels statistically similar to the levels at postprocess decontamination, meaning these are the most effective at killing bacteria of all the chlorine concentrations tested. These data suggest the use of at least 100 ppm chlorine sanitizer solution is a good method to sanitize hard-to-clean produce washing machines, yielding an approximate 4 log CFU reduction of the inoculated bacteria.