Log Reduction Research Articles

Green solutions for treating groundwater polluted with nitrates, pesticides, antibiotics, and antibiotic resistance genes for drinking water production.

The present study evaluates for the first time the seasonal performance of an innovative green groundwater treatment. The pilot plant combines microalgae-bacteria treatment and a cork-wood biofilter to reduce nitrates, pesticides, antibiotics (ABs), and antibiotic resistance genes (ARGs) from groundwater. Groundwater had nitrate concentrations ranging from 220 to 410mg/L, while ABs (sulfonamides and fluoroquinolones) and pesticides (triazines) were detected at concentrations ranging from a few ng/L to 150ng/L. Only the gene targets sul1, tetM and the class 1 integron-integrase gene (intl1) were detected in the groundwater. The microalgae-biofilter treatment system effectively removed 15%-98% of nitrates, depending on the season, and consistently eliminated over 90% of ABs and pesticides year-round. Among the components of the treatment system, the microalgal system was the most effective at removing ABs and pesticides. However, the cork-wood biofilter showed superior performance in reducing the bacterial load in groundwater, achieving more than a 1-log reduction in the absolute abundance of genes such as sul1 and intl1. The accumulation of ABs and pesticides in microalgae biomass was minimal or undetectable (<20ng/g of fresh weight). Overall, our results indicate that the microalgae-biofilter treatment plant is an effective solution for significantly reducing nitrates, antibiotics, and pesticides from groundwaters, while also producing a valuable biomass, and meeting drinking water standards during warmer months.

Robotic versus manual disinfection of global priority pathogens at COVID-19 dedicated hospitals.

Twelve bacterial families were identified as global priority pathogens by the World Health Organization in 2017, recognizing the greatest threat they pose to human health and the declining antibiotic efficacy. Robotics has emerged as a swift and contactless tool for disinfecting bacterial surface contamination in healthcare facilities, however, head-to-head comparison of disinfection efficacy of robotic versus manual disinfections is limited. This study aimed at comparing how robotic disinfection performs over manual disinfection against the global priority pathogens in the healthcare setting. A spraying disinfection robot was developed, and its disinfection efficacy was compared against manual disinfection during July 2020-December 2020. Disinfections were performed on the clinical surfaces and inanimate objects at two hospitals in Nepal using robotic or manual application of a disinfectant (NaOCl). Swab samples from floor, bed, doorknob, and medical devices at both hospitals were collected before and after disinfection and examined for total heterotrophic plate count and bacterial pathogens were identified based on Gram's staining and biochemical characteristics. Disinfection outcomes were reported as log reduction (log10 CFU/inch2) of heterotrophic count and presence or absence of target bacteria. A total of 76 samples were collected from two study sites including major pathogens: Staphylococcus aureus, Escherichia coli, Acinetobacter spp., and Klebsiella pneumoniae, among others. Both robotic and manual disinfection significantly reduced microbial load (log 2.3 to log 5.8) in the hospitals. No pathogens were detected post-disinfection using the robot. The use of robotic disinfection was more effective, significantly reducing more bacterial load (log 5.8) compared to manual disinfection (log 3.95). Our results showed better efficacy of robotic disinfection compared to manual disinfection of hospital surfaces, and thus contactless robotic disinfection is recommended for disinfecting bacterial contamination of surfaces in the hospital and clinical settings as it favors patient safety against global priority pathogens.

Inactivation of S. mutans dental biofilm by using Cold Atmospheric Plasma

Abstract S. mutans cells in oral cavity could adhere to surfaces of the teeth form the bacterial biofilm, strongly resist daily cleaning and brushing. The growth of the bacterial protected by the biofilm may lead to dental plaque formation and tooth decay. Cold Atmospheric Plasma (CAP) generated from a capillary-guided corona discharge is investigated for the inactivation of Streptococcus mutans biofilm associated with dental caries. The plasma device was optimised to generate a 4-mm plasma plume while maintaining a temperature near to ambient. The heat generated was not susceptible to thermal damage for the biofilm, as well as the oral cavity. Through experimental evaluations, the gaseous plasma plume from the CAP with a treatment durations of up to 15 minutes were responsible in reducing the S. mutans biofilm. The highest removal was achieved after 15-minute of CAP treatment. The results shown that a log-reduction of 3.08 of the cells in the S. mutans biofilm was killed during the treatment. The 10-minute treatment demonstrated a high value of log reduction at 1.79 compared to the control well. The efficacy is found to be strongly correlated to treatment duration whereby at the minimum duration of 1 minute treatment resulted a log reduction of 0.23. The outcomes of this research highlight CAP as a promising and safe approach for combating S. mutans biofilm. By offering a non-thermal alternative to traditional antimicrobial methods, CAP presents an opportunity to minimize harm to healthy tissues while effectively targeting biofilm.

Effectiveness of Cold Smoking on Inactivating Murine Norovirus in Salami-Like Pork Sausages (Mettwurst), and Hepatitis E Virus and Murine Norovirus in Solution

Hepatitis E virus (HEV) is a zoonotic virus that infects humans when virus-containing pork products are consumed. This study aimed to explore MNV (murine norovirus) and HEV inactivation during cold smoking and ripening/fermentation treatments used for salami-like sausages (mettwurst). MNV inactivation was monitored in culture medium solution and in sausage while being subjected to a salami-like sausage manufacturing process. The inactivation of MNV in the solution was also monitored at room temperature (RT) for four weeks. HEV inactivation was monitored in solution during the cold smoking process and at RT. A TCID50 assay was used to calculate the infectious MNV and HEV titres. MNV survival was modelled using Bayesian inference. MNV load in solution decreased by as much as 4.7 (SD 0.9) log10 TCID50/ml when it was subjected to the cold smoking process. Modelling revealed that 99.999% MNV might be inactivated during the treatment when observed at a level of 95% CI (Bayesian Confidence Interval). On the contrary, MNV load decreased by only 1.8 (0.2) log10 when stored at RT. The low-titre HEV in solution was inactivated (> 1.1 (0.2) log10) when treated, and at RT. However, MNV was resistant in the sausage matrix during the cold smoking process (log10 reduction of 1.9 (0.5) TCID50/ml). Based on modelling, a substantial amount of virus would remain in the product, even when the uncertainty was considered. Hence, viruses, here exemplified by MNV, may not be inactivated from salami-like pork sausages during manufacturing, which poses a risk for consumers in real-life situations.

A Novel Isotropic Optical Fiber: Antimicrobial Effect of Blue Light on Drug Resistant Organisms.

Drug-resistant organisms (DROs) necessitate the development of new therapies. Antimicrobial blue light (ABL) is a promising option, utilizing photoexcitation of endogenous bacterial components to generate reactive oxygen species, leading to bacterial death. The aim of this study is to investigate the effects of a novel isotropic optical fiber under in-vitro conditions on multidrug-resistant gram-negative Pseudomonas aeruginosa (MDR-Pa) and methicillin-resistant Staphylococcus aureus (MRSA). Time-to-kill assays were conducted in tubes containing 10 mL of 0.9% NaCl solution with an inoculum of 1 × 10⁵ CFU/mL for MDR-Pa or MRSA. The experiments were repeated at least three times per strain. Experimental tubes had either one (low power, LP) or two (high power, HP) optical fibers delivering five ABL wavelengths (405, 415, 435, 450, and 475 nm) over 60 min. Control tubes lacked optical fibers. Samples were taken at 0, 10, 20, 30, and 60 min, streaked on agar, and incubated to determine CFU/mL. Bactericidal reduction was defined as a ≥ 99.9% (≥ 3 log10) reduction in CFU/mL. One-way ANOVA were conducted. The novel isotropic optical fiber was able to exhibit bactericidal effects for MDR-Pa only under HP-ABL with a log10CFU/mL ± SD difference of -3.71 ± 0.01 at 60 min (p = 0.03). Conversely, the optical fiber exhibited bactericidal effects on MRSA under both LP-ABL and HP-ABL with a log10CFU/mL±SD difference of -3.73 ± 0.08 at 60 min (p = 0.03) and -3.07 ± 0.28 at 20 min (p = 0.02), respectively. The isotropic optical fiber demonstrated bactericidal effects on MRSA and MDR-Pa in in-vitro studies and shows potential as a therapeutic option for DROs.

Antimicrobial Efficacy of Five Wound Irrigation Solutions in the Periprosthetic Joint Infection Microenvironment In Vitro and Ex Vivo.

Background/Objectives: Periprosthetic joint infections (PJI) are difficult to treat due to biofilm formation on implant surfaces and the surrounding tissue, often requiring removal or exchange of prostheses along with long-lasting antibiotic treatment. Antiseptic irrigation during revision surgery might decrease bacterial biofilm load and thereby improve treatment success. This in vitro study investigated and compared the effect of five advanced wound irrigation solutions to reduce bacterial burden in the PJI microenvironment. Methods: We treated in vitro biofilms grown on titanium alloy implant discs with clinical bacterial strains isolated from patients with PJIs, as well as abscess communities in a plasma-supplemented collagen matrix. The biofilms were exposed for 1 min to the following wound irrigation solutions: Preventia®, Prontosan®, Granudacyn®, ActiMaris® forte ('Actimaris'), and Octenilin®. We measured the bacterial reduction of these irrigation solutions compared to Ringer-Lactate and to the strong bactericidal but not approved Betaseptic solution. Additionally, ex vivo free-floating bacteria isolated directly from clinical sonication fluids were treated in the same way, and regrowth or lack of regrowth was recorded as the outcome. Results: Irrigation solutions demonstrated variable efficacy. The mean CFU log10 reduction was as follows: Octenilin, 3.07, Preventia, 1.17, Actimaris, 1.11, Prontosan, 1.03, and Granudacyn, 0.61. For SACs, the reduction was: Actimaris, 8.27, Octenilin, 0.58, Prontosan, 0.56, Preventia, 0.35, and Granudacyn, 0.24. Conclusions: All solutions achieved complete bacterial eradication in all tested ex vivo sonication fluids, except Granudacyn, which was ineffective in 33% of the samples (2 out of 6). Advanced wound irrigation solutions have the potential to reduce bacterial burden in the PJI microenvironment during revision surgery. However, their efficacy varies depending on bacterial species, growth state, and the composition of the irrigation solution. This underscores the importance of considering these factors when developing future PJI-specific irrigation solutions.

Control of rotavirus by sequential stress of disinfectants and gamma irradiation in leafy vegetable industry.

Rotavirus (RV) causes severe gastroenteritis in infants and young children worldwide. Fresh produce has been reported as a source of RV infection during production and harvesting, leading to foodborne illness. Cases of contamination from contact surfaces have also been reported. Therefore, this study applied chemical methods (chlorine dioxide [ClO2], peracetic acid [PAA]), physical methods (gamma irradiation), and a combination of methods (disinfectants+gamma irradiation) to inactivate RV on food contact surfaces (stainless steel) and food (lettuce). Furthermore, the changes in food quality after the combined treatments were assessed. The results of the chemical treatment showed that RV was reduced below the detection limit after treatment for 1min with 20ppm ClO2 or 120ppm PAA in RV suspension. On stainless steel, treatment with 200ppm ClO2 or 2,000ppm PAA reduced contaminated RV by more than 4 log. A 5min treatment with 50ppm ClO2 or 80ppm PAA on lettuce reduced the RV by 1.79 and 0.75 log, respectively. Treatment with 4kGy of gamma irradiation resulted in more than 5 log reduction in suspensions and 3.27 log reduction on food. The sequential treatments, including 30ppm ClO2 followed by 1.5kGy gamma irradiation and 80ppm PAA followed by 1.5kGy gamma irradiation, showed additional inactivation effects (p<0.05) compared to each single treatment. No changes in food quality (color difference and texture) were observed after any treatments, suggesting that the combined treatment of both ClO2 and gamma irradiation and PAA and gamma irradiation can be applied in the fresh food industry to reduce RV contamination.

Protection induced by Streptococcus pneumoniae extracellular vesicles against nasal colonization and invasive infection in mice and the role of PspA

Diseases caused by Streptococcus pneumoniae (pneumococcus) produce a great impact on public health, killing about one million people annually despite available vaccines. Recent research has revealed that the pneumococcus produces extracellular vesicles (pEVs), which display selective cargo and hold potential for vaccine development. Here, we evaluated the immunogenicity and protective potential of pEVs derived from a non-encapsulated pneumococcal strain (R6) using murine models of pneumococcal colonization and invasive pneumonia. Characterization of the immune response revealed that while pEVs contain multiple virulence determinants, immunization with these nanoparticles only induces antibodies against a subset of them. Specifically, subcutaneous immunization elicits a high antibody response against PspA, a modest response against PrsA, and limited response against Ply, MalX and PsaA. The antibody response was further supported by agglutination studies, showing that sera from pEV immunized mice agglutinate pneumococci and that PspA contributes to this response in a strain-dependent manner. Subcutaneous immunization with pEVs provides protection in the invasive pneumonia model whereas nasal immunization results in one log reduction in pneumococcal colonization of the upper respiratory tract. Finally, PspA is a strong contributor to protection in the invasive model and provides a degree of protection even across heterologous families of PspA. We conclude that pEVs demonstrate potential for vaccine development, protecting across capsular types and providing some degree of protection across heterologous PspA variants.

Native and cationic cellulose nanofibril films enriched with avocado seed compounds as a green alternative for potential wound care applications

Cellulose nanofibrils (CNF) show great potential for skin wound care and healing due to their biocompatibility, non-cytotoxicity, and high swelling with good mechanical stability. In the presented study, for the first time native and cationized cellulose nanofibrils were used in combination with avocado seeds extracts obtained with different extraction methods (ASE), as an alternative to a well-known antibiotic, Clindamycin, to produce films with high and long-lasting antimicrobial efficacy. The swelling capacity of prepared films and extracts/antibiotic release kinetics were studied at different pH values to evaluate pH response behavior.All developed films exhibited high bacteriostatic and bactericidal activity against Gram-negative Escherichia coli and G-positive Staphylococcus aureus, resulting in up to 100 % bacterial reduction with the log reduction factor up to 5.64 or 6.50, at 14.2 mg of avocado seed extract or clindamycin integrated in the 1 cm2 of CNF film. The high swelling capacity (up to 65.67 %) and stability of avocado seed extracts-enriched CNF films provide a suitable moisture environment and a sustainable release (up to 40.98 % in 48 h) of bioactive compounds. The prepared antibacterial films' chemical and morphological characteristics and pH-responsive behavior proved the potential applications in the cosmetics, biomedicine, and pharmaceutical industry.

Determination of Time Required for 5 Log Reduction of Foodborne Pathogens by High Hydrostatic Pressure Processing in Foods

Determination of Time Required for 5 Log Reduction of Foodborne Pathogens by High Hydrostatic Pressure Processing in Foods

Determination of an Effective Sanitizing Procedure for Listeria innocua in Personal Protective Equipment Used in Dairy Facilities.

The presence of Listeria monocytogenes in the dairy environment remains a food safety challenge. The source of microbial contamination may include employees and their personal protective equipment (PPE). This study investigated the effectiveness of cleaning protocols (i.e., detergents and mechanical action) and three chemical sanitizers commonly employed at dairy facilities against Listeria innocua contamination on different types of gloves, aprons, and boots. Coupons made of PPE material were inoculated with a two-strain cocktail of L. innocua suspended in either Phosphate Buffered Saline (PBS) or skim milk to determine the potential effect of organic matter. In general, peroxyacetic acid (0.20% (v/v)) was more effective at reducing Listeria counts on aprons and gloves compared to chlorine and quaternary ammonium at 200 ppm. Depending on the type of sanitizer, Listeria reductions ranged from 1.95 - 4.72 and 1.52 - 4.60 log CFU/in2 on aprons and gloves, respectively. In comparison, sanitizers achieved a 0.93 - 2.32 log CFU/in2 reduction on boot soles, with no significant differences observed among sanitizers. PVC (vinyl) gloves achieved lower Listeria log reductions than nitrile and latex gloves. Sanitizers were less effective on boots with wider and deeper lugs than those with shallow lugs. The presence of organic matter significantly reduced the antimicrobial efficacy of all sanitizers (<1 log CFU/in2 reduction). However, the inclusion of cleaning protocols with and without mechanical action achieved a ≥3 log CFU/in2 reduction in the different types of PPE. This study highlights the importance of scrubbing as an essential step to reduce Listeria on PPE.

Study on the Survival of Enteric Virus in Chilled and Frozen Oyster Meat Using MS2 Bacteriophage As a Surrogate

This study utilized Escherichia coli bacteriophage MS2 as a surrogate to evaluate the survival of enteric viruses in oyster meat. The MS2 phage was propagated in its host, Escherichia coli, spiked into oyster meat at a concentration of 8.6 x10¹⁰ PFU/ml (10.93 log CFU/ml) and stored under chilled conditions on ice and at -20°C (frozen storage). Phage titres were measured using the soft agar overlay method, with sampling conducted every second day for ice-stored meat and every fifth day for frozen-stored meat. The survival analysis demonstrated that MS2 phages and by extension enteric viruses, could persist in ice for up to 10 days with counts reaching 4.78 log PFU/g. In frozen storage, the phages survived for up to 35 days, exhibiting 4 log reduction in viral counts. These results highlight a significant reduction in bacteriophage survival in oyster meat during both ice and frozen storage conditions.

Synergistic Enzybiotic Effect of a Bacteriophage Endolysin and an Engineered Glucose Oxidase Against Listeria.

Listeria monocytogenes represents one of the main risks for food safety worldwide. Two enzyme-based antimicrobials (enzybiotics) have been combined in a novel treatment against this pathogenic bacterium, resulting in a powerful synergistic effect. One of the enzymes is an endolysin from Listeria phage vB_LmoS_188 with amidase activity (henceforth A10), and the other is an engineered version of glucose oxidase from Aspergillus niger (GOX). Both enzymes, assayed separately against Listeria innocua, showed antibacterial activity at the appropriate doses. The combination of the two enzybiotics resulted in a synergistic effect with a log reduction in viable cells (log N0/N) of 4, whereas, taken separately, the same dose of A10 and GOX caused only 1.2 and 0.2 log reductions, respectively. Flow cytometry and microscopy analyses revealed that A10 treatment alone induced the aggregation of dead cells. L. monocytogenes showed higher resistance to single treatment with GOX or A10 than L. innocua. However, the synergic combination of A10 and GOX resulted in a high lethality of L. monocytogenes with a log N0/N higher than 5 (below the detection limit in our analysis). Altogether, these results represent a novel efficient and eco-friendly antimicrobial treatment against the most lethal food-borne pathogen.

Active plasma sterilizer for planetary protection and contamination control for space missions

This paper introduces a novel, compact plasma sterilization system, the Active Plasma Sterilizer (APS), for planetary protection space missions. The development of the APS system is done through iterative testing and design modifications aimed at addressing decontamination modalities for time and temperature, cleaning adhesive surfaces, and cleaning protocols beyond alcohol and bleach. Decontamination testing of Deinococcus radiodurans, Geobacillus stearothermophilus (spore forming bacteria), and Aspergillus fumigatus (fungi) was verified for the APS on relevant materials of 4 to 5 log reduction up to complete killing in 45 min or less. The material compatibility testing of the APS performed with Stainless Steel 316, Teflon PTFE, and FR-4 PCB using a single exposure showed no visible material degradation through SEM analysis. This study demonstrates the efficacy of the APS technology for use with planetary protection due to its low-temperature operation, low weight and size, zero-plumbing requirements, safety features, decontamination capabilities, and material compatibility.

New Strategy for the Covalent Immobilisation of Phenolic Compounds on Silica Particles to Fight Against Foodborne Pathogens.

The immobilisation of essential oil components (EOCs) on food-grade supports is a promising strategy for preserving liquid foods without the drawbacks of direct EOC addition such as poor solubility, high volatility, and sensory alterations. This study presents a novel method for covalently immobilising EOCs, specifically thymol and carvacrol, on SiO2 particles (5-15 µm) using the Mannich reaction. This approach simplifies conventional covalent immobilisation techniques by reducing the steps and reagents while maintaining antimicrobial efficacy and preventing compound migration. The antimicrobial effectiveness of the EOC-SiO2 system, applied as an additive, was tested against foodborne pathogens (Escherichia coli, Salmonella enterica, Staphylococcus aureus, and Listeria monocytogenes) inoculated into phosphate buffer solution and fresh apple juice. The results showed high antimicrobial activity, with inactivation exceeding 4-log reductions, depending on the EOC type, target microorganism, and medium. Moreover, the addition of functionalised particles did not affect the juice organoleptic properties. This study demonstrates that the Mannich reaction is an effective method for developing antimicrobial systems based on the covalent immobilisation of EOCs on silica particles, and offers a practical solution for food preservation without compromising food quality.

Durlobactam in combination with β-lactams to combat Mycobacterium abscessus.

Mycobacterium abscessus (Mab) presents significant clinical challenges. This study evaluated the synergistic effects of a β-lactam and β-lactamase inhibitor combination against Mab and explored the underlying mechanisms. Synergy was assessed through MIC tests and time-kill studies, and binding affinities of nine β-lactams and BLIs to eight target receptors (L,D-transpeptidases [LDT] 1-5, D,D-carboxypeptidase, penicillin-binding protein [PBP] B, and PBP-lipo) were assessed using mass spectrometry and kinetic studies. Thermal stability and morphological changes were determined. Imipenem demonstrated high binding affinity to LDTs and PBPs, with extremely low inhibition constants (Ki,app; ≤0.002 mg/L for LDT1-2, ≤0.6 mg/L for PBPs), while cephalosporins, sulopenem, tebipenem, and amoxicillin exhibited moderate to low binding affinity. Durlobactam inactivated BlaMab and LDT/PBPs more potently than avibactam. The Ki,apps of durlobactam for PBP B, PBP-lipo, and LDT2 were below clinically achievable unbound concentrations, while avibactam's Ki,app for LDT/PBPs exceeded the clinical concentrations. Single β-lactam treatments resulted in minimal killing (~1 log10 reduction). Although avibactam yielded no effect, combinations with avibactam showed a significant reduction (~4 log10 CFU/mL). Durlobactam alone showed ~2 log10 reduction, and when combined with imipenem or two β-lactams, durlobactam achieved near-eradication of Mab, surpassing the current therapy (amikacin + clarithromycin + imipenem/cefoxitin). Inactivation of PBP-lipo by sulopenem, imipenem, durlobactam, and amoxicillin (with avibactam) led to morphological changes, showing filaments. This study demonstrates the mechanistic basis of combinations therapy, particularly imipenem + durlobactam, in overcoming β-lactam resistance in Mab.

Design and development of Vaginal wall mimicking Poly (ε-caprolactone) based nanofibrous prosthetic mesh for pelvic organ prolapse: Evaluation of biocompatibility and antibacterial ability

Abstract Mechanical non-conformance of conventionally used transvaginal non-degradable meshes has led to complications like organ perforation, dyspareunia caused by mesh stiffness, and stress shielding. In this study, we have solved the dire need of mimicking the mechanical properties of vaginal wall by designing and developing a soft and elastic mesh made of polycaprolactone (PCL), citric acid modified polyethylene glycol (PEGC) and zinc oxide (ZnO) prepared through electrospinning and is tested in-vitro and in-vivo. Mesh containing 90:10:0.1 of PCL, PEGC and ZnO (PEGC-15 0.1ZnO mesh), conformed to the mechanical properties of vaginal wall of pelvic floor, has burst strength of ~35 N even after gamma-sterilization and 28 days of degradation in in-vitro. The in-vitro studies using adipose-derived stem cells revealed that PCL-PEGC-15 0.1ZnO meshes were biocompatible and supported higher collagen production than commercial mesh. In-vitro bacterial adhesion study showed 2-log reduction compared to the commercially available mesh for prolapse treatment. Initial biocompatibility assessment in rabbit model also showed that PCL-PEGC-15 0.1ZnO mesh is biocompatible and supports fibrosis throughout the mesh. The softness and flexibility of PCL-PEGC-15 0.1ZnO mesh based on in-vitro trials and initial in-vivo trials has proved to have a potential clinical impact for pelvic floor repair treatment.

Synergy of sodium dodecyl sulfate and citric acid in removing bacterial biofilms in hydroponic farming facilities.

This research explored various concentrations of sodium dodecyl sulfate (SDS) and citric acid (CA), both individually and in combination, to assess their effectiveness against Salmonella biofilms in hydroponic agriculture systems. Results demonstrated that a combined sanitizer of 0.1% SDS (1.0±0.1 log reduction when used alone) and 1% CA (1.4±0.3 log reduction when used alone) was highly effective in eliminating Salmonella biofilms from PVC pipes in hydroponic systems, reducing biofilm levels to below detectable limits (> 5.6 log reduction when used in combination). Confocal laser scanning microscopy (CLSM) showed significantly greater proportions of damaged/dead cells in the 0.1% SDS- and 1% CA-treated samples (82.6±2.6%) than in the single treatment with 0.1% SDS (26.1±3.0%) and 1% CA (31.6±2.5%) (P<0.05). Fourier transform infrared (FTIR) spectroscopy together with analysis of proteins and polysaccharides in the extracellular polymeric substances (EPS) of the biofilm matrices showed that the treatment not only affected bacterial viability but also significantly reduced the biomass of the biofilm. In summary, this research provides a foundation for the development of improved cleaning protocols in hydroponic systems, promoting safer and more sustainable farming practices.

Disinfection of Activated Sludge by Combination of the Fenton Reagent and Physical Treatment

Biological wastewater treatment plants could serve as an important alternative to renewable biological nitrogen mines, which are locally available and have a low carbon footprint. Recent progress in Fenton processes has revealed their potential use for sludge treatment to decrease organic contamination and pathogens. The aim of this study was to determine the optimal concentrations of metal catalyst Fe(II) and hydrogen peroxide H2O2 for activated sludge (AS) disinfection using the Fenton process at near-neutral pH, alone and in combination with thermal treatment and UV radiation. The efficiency of the 48 h treatment was evaluated by log reduction, fluorescein diacetate (FDA) hydrolysis activity, concentration of pharmaceuticals, changes in antimicrobial resistance, and ecotoxicity. Using the desirability function approach, a combination of 239 mM H2O2 and 8.6 mM Fe(II) was found to be optimal in frames of the chosen concentrations of reagents. The FDA hydrolysis activity correlated with log reduction at 287 mM H2O2 and different Fe(II) concentrations. Sludge treatment resulted in the removal of ciprofloxacin by 65.5%. The sets with the highest log reduction, i.e., additionally treated by heating and UV, were accompanied by increasing ecotoxic effects on crustaceans, Thamnocephalus platyurus. The Fenton process shows prospective ways on sludge stabilization for its application as a fertilizer.

Alcohol-based antisepsis without the use of chlorhexidine for arthroscopy in horses.

Alcohol-based antisepsis has shown experimentally to be as effective as 4% chlorhexidine gluconate (CHG) at reducing bacterial counts (colony forming units; CFU) on equine skin. Our objectives were to determine the immediate and post-surgical reduction in CFU/mL on equine skin prepared with CHG-based or 70% isopropyl alcohol (IPA)-based (without CHG) protocols in a clinical setting with arthroscopic surgery. Our hypotheses were that the log10CFU/mL reduction would not significantly differ between protocols immediately after preparation or at the end of surgery. Six horses underwent a 40 min bilateral tarsocrural joint arthroscopy with each limb randomly assigned to Group A or B. Group A tarsocrural joints underwent a rough scrub using 4% CHG and a 5 min sterile scrub using 2% CHG. Group B underwent a rough scrub with neutral soap followed by a 90s sterile scrub with IPA. Samples were collected before rough scrub (T0), immediately after sterile scrub (T1), and end of surgery (T2). CFU/mL were determined in duplicate and were log-transformed and averaged. ANOVA models compared the immediate reduction (T0-T1) and sustained reduction (T0-T2) between treatment groups. The immediate and sustained log10CFU/mL reduction between groups was not different (P=0.46, P=0.42). Both groups achieved at least a 2-log immediate and sustained reduction. Limitations include small population size, short surgical duration, length of follow-up, and researchers were not blinded to treatment during sampling. This study demonstrates efficacy of IPA-based antisepsis, without the need for CHG, and supports further investigation in clinical surgery as an acceptable method of surgical site preparation.