CFU Counts Research Articles

Drought Tolerant Enterobacter sp./Leclercia adecarboxylata Secretes Indole-3-acetic Acid and Other Biomolecules and Enhances the Biological Attributes of Vigna radiata (L.) R. Wilczek in Water Deficit Conditions.

Simple SummaryDrought stress is one of the most important factors that significantly affects agricultural lands and reduces the production of various crops. Among bean crops, Vigna radiata (mung bean) is a highly nutritious food crop that provides protein, carbohydrates, several essential minerals, amino acids, vitamins, and antioxidants. To resolve the problem of drought-affected agriculture of mung bean, we focused on finding a novel and sustainable solution by using a drought-tolerant bacterium Enterobacter sp./Leclercia adecarboxylata PAB19 that produces significant amounts of plant growth-promoting bioactive compounds and colonizes the roots of mung bean plants. By performing a series of in vitro and in situ (on field) experiments, we conclude that the bacterium PAB19 holds a great potential to mitigate drought stress. Several agriculturally important parameters were enhanced by the bacterial activity which was suppressed by the drought stress induced by a chemical PEG-6000 without bacterial inoculation. Conclusively, strain PAB19 can be applied to alleviate drought stress by improving the biological attributes of mung bean under water-deficit conditions.Drought or water stress is a limiting factor that hampers the growth and yield of edible crops. Drought-tolerant plant growth-promoting rhizobacteria (PGPR) can mitigate water stress in crops by synthesizing multiple bioactive molecules. Here, strain PAB19 recovered from rhizospheric soil was biochemically and molecularly characterized, and identified as Enterobacter sp./Leclercia adecarboxylata (MT672579.1). Strain PAB19 tolerated an exceptionally high level of drought (18% PEG-6000) and produced indole-3-acetic acid (176.2 ± 5.6 µg mL−1), ACC deaminase (56.6 ± 5.0 µg mL−1), salicylic acid (42.5 ± 3.0 µg mL−1), 2,3-dihydroxy benzoic acid (DHBA) (44.3 ± 2.3 µg mL−1), exopolysaccharide (204 ± 14.7 µg mL−1), alginate (82.3 ± 6.5 µg mL−1), and solubilized tricalcium phosphate (98.3 ± 3.5 µg mL−1), in the presence of 15% polyethylene glycol. Furthermore, strain PAB19 alleviated water stress and significantly (p ≤ 0.05) improved the overall growth and biochemical attributes of Vigna radiata (L.) R. Wilczek. For instance, at 2% PEG stress, PAB19 inoculation maximally increased germination, root dry biomass, leaf carotenoid content, nodule biomass, leghaemoglobin (LHb) content, leaf water potential (ΨL), membrane stability index (MSI), and pod yield by 10%, 7%, 14%, 38%, 9%, 17%, 11%, and 11%, respectively, over un-inoculated plants. Additionally, PAB19 inoculation reduced two stressor metabolites, proline and malondialdehyde, and antioxidant enzymes (POD, SOD, CAT, and GR) levels in V. radiata foliage in water stress conditions. Following inoculation of strain PAB19 with 15% PEG in soil, stomatal conductance, intercellular CO2 concentration, transpiration rate, water vapor deficit, intrinsic water use efficiency, and photosynthetic rate were significantly improved by 12%, 8%, 42%, 10%, 9% and 16%, respectively. Rhizospheric CFU counts of PAB19 were 2.33 and 2.11 log CFU g−1 after treatment with 15% PEG solution and 8.46 and 6.67 log CFU g−1 for untreated controls at 40 and 80 DAS, respectively. Conclusively, this study suggests the potential of Enterobacter sp./L. adecarboxylata PAB19 to alleviate water stress by improving the biological and biochemical features and of V. radiata under water-deficit conditions.

Specificity and Heterogeneity of Trained Immunity in Hematopoietic Stem and Progenitor Cells

When innate immune cells and hematopoietic stem and progenitor cells (HSPCs) are exposed to pathogenic agents, they develop heightened responses to subsequent infection through a process called trained immunity. After exposure to a pathogen, bone marrow derived macrophages (BMDMs) generated from trained HSPCs are capable of enhanced pathogen clearance and cytokine production, while exhibiting persistent metabolic rewiring. Because some models of HSPC trained immunity are dependent on interferon gamma (IFNγ) signaling, and our lab has described extensive changes in HSC self-renewal and differentiation upon IFNγ exposure, we hypothesized that persistent IFNγ signaling induced by chronic infection results in reprogramming of HSPCs, causing improved non-specific immunity. To test our hypothesis, we generated a chimeric mouse model of trained immunity by transplanting control or M. avium-exposed HSPCs into naïve recipient mice. Mice that received M. avium trained HSPCs had decreased bacterial load, less splenomegaly, and fewer granulomas upon subsequent M. avium infection, indicating improved immunity. Furthermore, BMDMs generated from mice trained with a single dose of recombinant IFNγ (rIFNγ) exhibited increased pathogen clearance and metabolic profiles ex vivo. To test if rIFNγ training was sufficient to induce HSPC trained immunity in vivo, we isolated HSPCs from rIFNγ-exposed mice and challenged the recipients 4 months later. These in vivo experiments demonstrated that rIFNγ training was insufficient to induce substantial protection against subsequent M. avium challenge, but still induced BMDM metabolic rewiring four months post HSPC training. Collectively, our studies indicate that there are degrees of training that occur upon IFNγ exposure, likely related to the concentration and duration of the primary stimulus.To assess the specificity of cross protection of HSPC trained immunity, we utilized our chimeric mouse model and tested two different training and infection pathogens: M. avium and influenza. When we challenged M. avium-trained HSPC recipients with influenza, we found that although there was mildly decreased lung histopathology and increased production of IFNγ and TNFα, mice succumbed to infection like untrained controls. When we swapped the order of pathogens, we observed that mice receiving influenza-trained HSPCs produced BMDMs with increased killing capability and systemically higher IL-6 and RANTES levels, but these features were insufficient to significantly reduce bacterial CFU counts upon M. avium challenge. These transplant experiments indicate that trained immunity encoded in HSPCs is pathogen specific.To dissect the mechanism of M. avium-induced trained immunity in HSPCs, we performed RNAseq analysis on M. avium-trained HSPCs post-transplant and cross referenced it with RNAseq and WGBS data on primary M. avium-exposed HSPCs. These studies showed consistent differences in cellular signaling, metabolism, immunity, and antigen processing and presentation in the trained HSPCs, indicating that epigenetic and transcriptional reprogramming induced by M. avium exposure is durable following transplant and secondary challenge.To ascertain whether transcriptional changes are homogeneous throughout the HSC compartment, we completed scRNA-seq on naïve and M. avium-exposed hematopoietic cells. We found that genes upregulated upon M. avium exposure in HSCs, including Batf2 and Cxcl9, were induced in a subset of HSPCs, indicating that there is a heterogeneous response to training within the HSPC pool. Strikingly, the trained immunity signature was maintained in neutrophils and macrophages but lost in mature B cells, indicating specific propagation of genetic signatures induced by training in certain lineages. Finally, we found an emerging population of HSCs with B cell gene signatures upon M. avium exposure. Emergence of this HSPC subpopulation may suggest the development of a cell that acts as a direct intermediate between HSC and B cells following training.Our work shows that trained immunity induced by M. avium and persistent IFNγ signaling is pathogen-specific and heterogeneous among primitive HSPCs. Emergence of specific responder cell populations within the HSPC pool may be responsible for enhanced protection against specific infection stimuli, whereas the presence of non-responders may insure long term health of the HSPC pool. DisclosuresNo relevant conflicts of interest to declare.

Computational Design and Lab-Based Investigation of a Novel Small-Molecule Inhibitor That Targets CadA Metal Efflux Pump Activity in Hospital Methicillin-Resistant Staphylococcus Aureus: A Research Protocol

Introduction: Heavy metal exposure has been previously reported to decrease bacterial growth. During the growing antibiotic crisis in healthcare settings, metals may reduce bacterial burden in hospital environments. Despite proving successful, this has driven the evolution of metal-resistant strains like methicillin-resistant Staphylococcus aureus (MRSA). By expelling cadmium and zinc through surface efflux pumps such as CadA, MRSA is able to thrive in metal-rich environments. This protocol investigates the inhibitory activity of Scinapsin, a novel small-molecule inhibitor designed to bind the catalytic site of CadA. Scinapsin could be applied to clinical settings to combat metal resistance in MRSA populations amidst the COVID-19 pandemic. Methods: Computational biochemistry is used to characterize the structure of the S. aureus CadA protein. Small-molecule library screening generated a hit compound, which after modification to improve binding affinity produced the final Scinapsin structure. Several MSRA strains were screened for the presence of CadA from which the most favourable strain for the experiment is chosen (i.e. prevalence in hospitals, CadA expression levels). For the experimental protocol, MRSA strains with metal resistance are incubated with increasing concentrations of Scinapsin, either in the presence or absence of zinc and cadmium (at 50% of predetermined MIC). Samples are then diluted and plated to allow for CFU counting. Results: Scinapsin is anticipated to have an inhibitory effect on MRSA growth in the presence of metals at 50% MIC, confirming the successful inactivation of CadA function. A saturation point may also occur at higher concentrations of Scinapsin where no further growth inhibition is achieved. Discussion: Docking analysis has confirmed the theoretical feasibility for Scinapsin to act as a CadA-specific inhibitor. In an in vitro setting like the one presented, Scinapsin should allow for excess zinc and cadmium to accumulate in the cytoplasm and ultimately cause cell death. Further experiments could aim to confirm the proposed biological mechanism of antibacterial activity. Conclusion: Scinapsin holds promise in reversing metal resistance in hospital MRSA populations and may pave the way for other small-molecule antibacterial drugs. Future research is needed to determine safe levels of Scinapsin exposure for humans and how this inhibitor affects other hospital microbes.

Efficiency of ultraviolet light for disinfection of fertile broiler eggs

ABSTRACT This study aimed to evaluate the effectiveness of ultraviolet light in reducing bacterial load of eggshells and the impact of experimental disinfection on hatching, embryo mortality, and time-borne distribution using broiler breeder hens of different ages (38, 42, and 48 weeks old). Fertile eggs were subjected to different exposure periods (5, 7, and 9 minutes) of UV light (UV-C) with a 254 nm wavelength. For controls, eggs disinfected with paraformaldehyde (5.3 g/m3) and eggs not disinfected (NC). After subjection to disinfection protocols, the eggs were placed into sterile plastic bags containing 20 mL of peptone saline solution (0.1% m:v) and massaged for 1 minute to release the bacterial load. Aliquots of this solution were incubated in specific medium for bacterial growth for 48 hours at 37ºC for subsequent CFU counts. To evaluate the effects of disinfection on production, eggs previously disinfected by UV-C (9 min) and paraformaldehyde and NC eggs were candled between incubation days 10 and 13 and at the end of the incubation period to assess embryonic mortality. Hatchability distribution was performed every 8 hours. The 9 minutes 254nm UV-C light exposure was able to disinfect viable eggs and matched the effectiveness of the paraformaldehyde technique.

Effect of TiF4/NaF and chitosan solutions on biofilm formation and prevention of dentin demineralization

ObjectiveThis study evaluated the effect of experimental solutions containing TiF4/NaF and chitosan on bacterial species of microcosm biofilm and on dentin demineralization. DesignMicrocosm biofilm was produced from human saliva mixed with McBain medium (0.2% sucrose) on bovine dentin for 5 days, under 5% CO2 and 37 °C. From the 2nd day to 5th day, the treatments were applied (1×60s/day) as following: (1) NaF (500 ppm F−, positive control); (2) TiF4 and NaF (TiF4: 190 ppm Ti4+ and 300 ppm F-; NaF: 190 ppm F−); (3) similar to 2 plus 0.5% chitosan (Ch 500 mPa.s, 75% deacetylation); (4) phosphate buffer solution (negative control); and (5) 0.5% chitosan (Ch 500 mPa.s, 75% deacetylation). CFU counting was performed for total microorganism, total streptococci, total lactobacilli and mutans streptococci. Dentin demineralization was measured by transverse microradiography-TMR. The data were compared using ANOVA/Tukey or Kruskal-Wallis/Dunn tests (p < 0.05). ResultsNo differences were found between the treatments with respect to CFU counting (p > 0.05). Dentin treated with TiF4/NaF plus chitosan solution presented the lowest demineralization compared to the negative control and pure chitosan solution. On the other hand, this experimental solution did not significantly differ from TiF4/NaF solution, being both able to significantly reduce mineral loss. ConclusionTiF4/NaF plus chitosan solution, at suitable pH to be clinically applicable, had no antimicrobial effect, but it was able to reduce dentin caries development under this model.

Flow cytometry method for absolute counting and single-cell phenotyping of mycobacteria

Detection and accurate quantitation of viable Mycobacterium tuberculosis is fundamental to understanding mycobacterial pathogenicity, tuberculosis (TB) disease progression and outcomes; TB transmission; drug action, efficacy and drug resistance. Despite this importance, methods for determining numbers of viable bacilli are limited in accuracy and precision owing to inherent characteristics of mycobacterial cell biology—including the tendency to clump, and “differential” culturability—and technical challenges consequent on handling an infectious pathogen under biosafe conditions. We developed an absolute counting method for mycobacteria in liquid cultures using a bench-top flow cytometer, and the low-cost fluorescent dyes Calcein-AM (CA) and SYBR-gold (SG). During exponential growth CA + cell counts are highly correlated with CFU counts and can be used as a real-time alternative to simplify the accurate standardisation of inocula for experiments. In contrast to CFU counting, this method can detect and enumerate cell aggregates in samples, which we show are a potential source of variance and bias when using established methods. We show that CFUs comprise a sub-population of intact, metabolically active mycobacterial cells in liquid cultures, with CFU-proportion varying by growth conditions. A pharmacodynamic application of the flow cytometry method, exploring kinetics of fluorescent probe defined subpopulations compared to CFU is demonstrated. Flow cytometry derived Mycobacterium bovis bacillus Calmette-Guérin (BCG) time-kill curves differ for rifampicin and kanamycin versus isoniazid and ethambutol, as do the relative dynamics of discrete morphologically-distinct subpopulations of bacilli revealed by this high-throughput single-cell technique.

Cold Atmospheric Plasma Jet as a Possible Adjuvant Therapy for Periodontal Disease.

Due to the limitations of traditional periodontal therapies, and reported cold atmospheric plasma anti-inflammatory/antimicrobial activities, plasma could be an adjuvant therapy to periodontitis. Porphyromonas gingivalis was grown in blood agar. Standardized suspensions were plated on blood agar and plasma-treated for planktonic growth. For biofilm, dual-species Streptococcus gordonii + P. gingivalis biofilm grew for 48 h and then was plasma-treated. XTT assay and CFU counting were performed. Cytotoxicity was accessed immediately or after 24 h. Plasma was applied for 1, 3, 5 or 7 min. In vivo: Thirty C57BI/6 mice were subject to experimental periodontitis for 11 days. Immediately after ligature removal, animals were plasma-treated for 5 min once—Group P1 (n = 10); twice (Day 11 and 13)—Group P2 (n = 10); or not treated—Group S (n = 10). Mice were euthanized on day 15. Histological and microtomography analyses were performed. Significance level was 5%. Halo diameter increased proportionally to time of exposure contrary to CFU/mL counting. Mean/SD of fibroblasts viability did not vary among the groups. Plasma was able to inhibit P. gingivalis in planktonic culture and biofilm in a cell-safe manner. Moreover, plasma treatment in vivo, for 5 min, tends to improve periodontal tissue recovery, proportionally to the number of plasma applications.

Activity of chlorhexidine formulations on oral microorganisms and periodontal ligament fibroblasts.

Given the importance of microorganisms in the pathogenesis of the two most prevalent oral diseases (i.e. caries and periodontitis), antiseptics are widely used. Among the antiseptics chlorhexidine (CHX) is still considered as gold standard. The purpose of this in-vitro-study was to determine the antimicrobial activity of new CHX digluconate containing formulations produced in Switzerland. Two test formulations, with 0.1% or 0.2% CHX (TestCHX0.1, TestCHX0.2) were compared with 0.1% and 0.2% CHX digluconate solutions (CHXph0.1, CHXph0.2) without additives and with a commercially available formulation containing 0.2% CHX digluconate (CHXcom0.2). The minimal inhibitory concentrations (MIC) of the CHX formulations were determined against bacteria associated with caries or periodontal disease. Then the anti-biofilm activities of CHX preparations were tested regarding inhibition of biofilm formation or against an existing biofilm. Further, the cytotoxicity of the CHX preparations against periodontal ligament (PDL) fibroblasts was measured. There were no or only minor differences of the MIC values between the CHX preparations. Except for 0.1% CHXph, all formulations blocked the formation of the biofilms. When analyzing the effect on an established “cariogenic” biofilm, the TestCHX0.2 was most active (- 3.5 log10 colony forming units (cfu); p<0.001 vs. control). The cfu counts of an established periodontal biofilm were most decreased by CHXcom0.2 (-3.9 log10), followed by TestCHX0.2 (-3.34 log10) and CHXph0.2 (-3.0 log10 cfu) (each p<0.001 vs. control). All CHX preparations reduced the viability of the PDL fibroblasts. Taken together, the Swiss made test mouth rinses have an equal or better antibacterial and anti-biofilm activity as the respective CHX solutions and can be recommended.

In-vitro Comparative Assessment of Antibacterial and Anti-adherent Effect of Two Types of Surface Modificants on Stainless Steel Orthodontic Brackets Against Streptococcus mutans

Objective: Comparative evaluation of antibacterial and anti-adherent properties of surface-modified stainless steel (SS) orthodontic brackets against Streptococcus mutans ( S. mutans). Materials and Methods: The study was conducted on 120 SS orthodontic McLaughlin, Bennett, Trevisi (MBT) 0.022″ slot by Leone, Italy. Orthodontic brackets that constituted the sample size were divided into 6 groups, consisting of 20 samples each in two control (non-surface coated) and four experimental groups. The experimental group’s surface coatings were photocatalytic zinc oxide (ZnO) and photocatalytic titanium oxide (TiO2), which were carried out by radiofrequency (RF) magnetron sputtering method for surface modification. Brackets were subjected to microbiological tests against S. mutans. For anti-adherence, weight change, pre- and postexposure, was evaluated to gauge the adherence of bacteria and colony-forming units/milliliter (CFU/mL) count measuring the survival rate of bacterial cells for antibacterial activity. Results: The TiO2-coated group showed statistically significant anti-adherence ( P-value &lt; .05) against S. mutans than control and ZnO groups. The CFU count of TiO2 group was lower than control as well as ZnO group. Conclusion: TiO2 is superior to ZnO and should be continued to be considered for surface modification of orthodontic brackets against White Spot Lesions (WSLs) and gingivitis.

Hydrogen-peroxide generating electrochemical bandage is active in vitro against mono- and dual-species biofilms

Biofilms formed by antibiotic-resistant bacteria in wound beds present unique challenges in terms of treating chronic wound infections; biofilms formed by one or more than one bacterial species are often involved. In this work, the in vitro anti-biofilm activity of a novel electrochemical bandage (e-bandage) composed of carbon fabric and controlled by a wearable potentiostat, designed to continuously deliver low amounts of hydrogen peroxide (H2O2) was evaluated against 34 mono-species and 12 dual-species membrane bacterial biofilms formed by Staphylococcus aureus, S. epidermidis, Enterococcus faecium, E. faecalis, Streptococcus mutans, Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella pneumoniae, Cutibacterium acnes, and Bacteroides fragilis. Biofilms were grown on polycarbonate membranes placed atop agar plates. An e-bandage, which electrochemically reduces dissolved oxygen to H2O2 when polarized at −0.6 VAg/AgCl, was then placed atop each membrane biofilm and polarized continuously for 12, 24, and 48 h using a wearable potentiostat. Time-dependent decreases in viable CFU counts of all mono- and dual-species biofilms were observed after e-bandage treatment. 48 h of e-bandage treatment resulted in an average reduction of 8.17 ± 0.40 and 7.99 ± 0.32 log10 CFU/cm2 for mono- and dual-species biofilms, respectively. Results suggest that the described H2O2 producing e-bandage can reduce in vitro viable cell counts of biofilms grown either in mono- or dual-species forms, and should be further developed as a potential antibiotic-free treatment strategy for treating chronic wound infections.

Planktonic and Biofilm-Associated Pseudomonas aeruginosa and Staphylococcus epidermidis Elicit Differential Human Peripheral Blood Cell Responses.

Despite the considerable progress made in recent years, our understanding of the human immune response to microbial biofilms is still poor. The aim of the present study was to compare the in vitro response of human peripheral blood mononuclear cells (PBMC) to biofilms and planktonic cells of Pseudomonas aeruginosa and Staphylococcus epidermidis, two bacterial species particularly relevant in patients with cystic fibrosis or undergoing endovascular catheterization, respectively. PBMC isolated from healthy donors were co-cultured with 24 h-old biofilms or with exponentially growing cells of both species. Following 24 h of co-culture, the expression of early activation markers and the levels of cytokines in the culture supernatants were assessed by flow cytometry, while biofilm biomass and architecture were evaluated by crystal violet staining, CFU count, and confocal microscopy. Around 20% of PBMC was activated in response to both biofilms and planktonic cells of P. aeruginosa. In contrast, planktonic cells of S. epidermidis induced a statistically higher degree of activation than their biofilm counterpart (25% versus 15%; p < 0.01). P. aeruginosa biofilms stimulated pro-inflammatory (TNF-α, IL-1β, IFN-γ, and IL-6) and anti-inflammatory (IL-10) cytokine production at statistically significant levels higher than its planktonic counterpart, while an opposite trend was observed with S. epidermidis. Differences in the architecture of the biofilms and in the number of PBMC infiltrating the biofilms between the two bacterial species may at least partially explain these findings. Collectively, the results obtained highlighted marked differences in the host–cell response depending on the species and the mode of growth (biofilms versus planktonic cultures), allowing speculations on the different strategies adopted by P. aeruginosa and S. epidermidis to persist in the host during the course of chronic infections.

A Comparison of One Shape and ProTaper Next Rotary Systems for Elimination of Enterococcus Faecalis from Root Canal: Microbiological and SEM Evaluation

Incomplete removal of micro- organisms from infected root canals is a common cause of failed endodontic treatment. The difficulty in eradication of Enterococcus faecalis from root canals plays an essential role in pathogenesis of persistent pulpal and periradicular infections. The aim of the present study was to compare the reduction of Enterococcus faecalis in root canals by mechanical instrumentation using two rotary systems (One Shape and ProTaper Next) and Hand K-file instrumentation by using microbiological and Scanning Electron Microscopy (SEM) evaluation. Fifty one freshly extracted mandibular premolars with a single root were collected. After pre-instrumentation sampling, they were divided into three groups, Group A, Group B and Group C in which biomechanical preparation was done using Hand K-File, OneShape and Protaper Next respectively. Reduction in pre- instrumentation and post- instrumentation values of Enterococcus faecalis were analysed using microbiological and SEM evaluation. Statistical analysis by paired ‘t’ test and p value showed that there was highly statistical significant difference in CFU count reduction between the pre-instrumentation and post-instrumentation values in all the groups (p&lt;0.001). Statistical analysis by Kruskal-Wallis Test and Mann-Whitney Test showed that at 1mm and 3mm level, Group A (Hand K-File) scored significantly higher value followed by Group B (OneShape Apical) and Group C (ProTaper Next). The most effective instrumentation technique in eliminating Enterococcus faecalis from the root canal was ProTaper Next system in comparison to OneShape Apical and Hand K-File.

Evaluation of an Environmental Transport Medium for Legionella pneumophila Recovery

The collection and storage of water-related matrices such as biofilm from collection to processing are critical for the detection of Legionella pneumophila by cultural and molecular tests. SRK™ is a liquid medium that acts both as an antimicrobial neutralizing agent and a transport medium for bacterial culture enumeration and is useful to maintain the stability of the sample from collection to analysis. The aims of this study were to evaluate Legionella pneumophila viability and bacterial nucleic acids’ stability in SRK™ medium over time at different storage conditions. Artificial bacterial inoculates with an approximate concentration of 104, 103 and 102 CFU/mL were made using Legionella pneumophila certified reference material suspended in SRK™ medium. Bacteria recovery was analyzed by cultural and molecular methods at time 0, 24 and 48 h at room temperature and at 0, 24, 48 and 72 h at 2–8 °C, respectively. SRK™ medium supported Legionella pneumophila culture viability with CFU counts within the expected range. The recovery after 72 h at 2–8 °C was 83–100% and 75–95% after 48 h at room temperature. Real-time PCR appropriately detected Legionella pneumophila DNA at each temperature condition, dilution and time point. Results demonstrated a good performance of SRK™ medium for the reliable recovery of environmental Legionella.

Highly Efficient Self-Repairing Slippery Liquid-Infused Surface with Promising Anti-Icing and Anti-Fouling Performance.

Smart slippery liquid-infused porous surfaces (SLIPSs) have aroused remarkable attention owing to tremendous application foreground in biomedical instruments and industry. However, challenges still remain in fabricating durable SLIPSs. In this work, a fast and highly efficient self-repairing slippery surface (SPU-60M) was fabricated based on a polyurethane membrane and silicone oil. By introducing a great quantity of reversible disulfide bonds into the polymer backbone and hydrogen bonds in the polymer interchain, this SLIPS material could be quickly repaired in 15 min with 97.8% healing efficiency. Moreover, the self-healing efficiency could be maintained at 42.75% after the 10th cutting-healing cycle. Notably, SPU-60M showed excellent self-repairing ability not only in an ambient environment but also in an underwater environment and at ultralow temperatures. Besides, the icing delay time (DT) of SPU-60M could be prolonged to 1182 s at -15 °C, and the ice adhesion strength was only 10.33 kPa at -30 °C. In addition, SPU-60M had excellent anti-fouling performance with BSA adsorption of 2.41 μg/cm2 and Escherichia coli CFU counts of 41 × 104. These findings provide a facile way to design highly efficient self-repairing SLIPSs with multifunctionality.

SHORT TERM EFFECTS OF PHOTODYNAMIC THERAPY ON CLINICAL, MICROBIAL AND BIOCHEMICAL PARAMETERS IN PATIENTS WITH CHRONIC PERIODONTITIS

Objectives: Photodynamic therapy applies to the elimination of target cells by reactive oxygen species using a photosensitizing agent and a sufcient wavelength of light. It is a new, non-invasive approach to preventing infection. It is now an upcoming alternative treatment modality for periodontitis patients as a supplement to traditional scaling and root planing. The objective of the present study was to assess and compare the effect of photodynamic therapy with conventional Scaling and Root planing in patients with chronic periodontitis. Methods: The study included a minimum of 5 non-smoking males with mild to moderate periodontitis. Clinical parameters such as plaque index, gingival index, gingival bleeding index, pocket probing depth, clinical attachment level; microbiological parameter – anaerobic bacterial CFU count in subgingival plaque samples and biochemical parameter – GCF SOD levels were evaluated at baseline and 28 days postoperatively. The obtained data were analyzed using SPSS (SYSTAT 12) statistical software. The Wilcoxon signed Rank test was used to compare the mean values of various parameters before and after treatment. Results: The results of the study show that all clinical parameters improved from baseline to day 28. Following therapy, the mean levels of the anaerobic bacterial CFU and GCF SOD have decreased dramatically. Conclusion: The results of this study suggest a signicant improvement in clinical, microbiological and Biochemical parameters with the use of PDT as an adjunct to conventional SRP in chronic periodontitis patients

Effectiveness of Oil-Based Denture Dentifrices-Organoleptic Characteristics, Physicochemical Properties and Antimicrobial Action.

Denture dentifrices must be effective and not deleterious to prosthetic devices. This study formulated and evaluated dentifrices based on oils of Copaifera officinalis, Eucalyptus citriodora, Melaleuca alternifolia, Pinus strobus, and Ricinus communis. Organoleptic characteristics (appearance, color, odor, taste), physicochemical properties (pH, density, consistency, rheological, abrasiveness, weight loss, and surface roughness) and antimicrobial (Hole-Plate Diffusion–HPD)/anti-biofilm (Colony Forming Units–CFU) action against Staphylococcus aureus, Streptococcus mutans, and Candida albicans were evaluated. Formulations were compared with water (negative control) and a commercial dentifrice (positive control). The data were analyzed by Kruskal-Wallis and Dunn tests (α = 0.05). The organoleptic and physicochemical properties were adequate. All dentifrices promoted weight losses, with high values for C. officinalis and R. communis, and an increase in surface roughness, without differing from each other. For antimicrobial action, C. officinalis and E. citriodora dentifrices were similar to positive control showing effectiveness against S. mutans and C. albicans and no dentifrice was effective against S. aureus; regarding the anti-biofilm action, the dentifrices were not effective, showing higher CFU counts than positive control for all microorganisms. The dentifrices presented satisfactory properties; and, although they showed antimicrobial action when evaluated by HPD, they showed no effective anti-biofilm action on multispecies biofilm.

Laminar airflow versus turbulent airflow in simulated total hip arthroplasty: measurements of colony-forming units, particles, and energy consumption

The optimal type of ventilation in operating theatres for joint arthroplasty has been debated for decades. Recently, the World Health Organization changed its recommendations based on articles that have since been criticized. The economic and environmental impact of ventilation is also currently an important research topic but has not been well investigated. To compare how large, high-volume, laminar airflow (LAF) and turbulent airflow (TAF) ventilation systems perform during standardized simulated total hip arthroplasty (THA), as they pertain to colony-forming units (cfu), particle counts, and energy consumption. Two identical operating theatres were used to perform simulated THA. The only difference was that one was equipped with LAF and the other with TAF. Cfu and particles were collected from key points in the operating theatre, and energy was measured for each simulation. Thirty-two simulations were done in total. LAF had significantly reduced cfu and particle count when compared with TAF, at both 100% and 50% air influx. Furthermore, it was shown that lowering the air influx by 50% in LAF did not significantly affect cfu or particles, although reducing the fresh air influx from 100% to 50% significantly lowered the energy consumption. Most simulations in TAF did not meet the cleanroom requirements. Cfu were significantly lower in LAF at both 100% and 50% air influx. It is possible to reduce fresh air influx in LAF operating theatres by 50%, significantly reducing energy consumption, while still maintaining cfu and particle counts below the ISO classification threshold required for THA surgery.

Effect of TiF4/NaF and chitosan solutions on the development of enamel caries under a microcosm biofilm model

ObjectivesTo evaluate the effect of experimental solutions containing TiF4/NaF and chitosan on bacterial species and on enamel caries prevention. MethodsMicrocosm biofilm was produced from human saliva mixed with McBain saliva (0.2% sucrose) on bovine enamel for five days, under 5% CO2 and 37 °C. From the second day until the end, the treatments were applied (1 × 60 s/day): (1) NaF (500 ppm F−, positive control); (2) TiF4 and NaF (TiF4: 190 ppm Ti4+ and 300 ppm F−; NaF: 190 ppm F−); (3) similar to 2 plus 0.5% chitosan (Ch 500 mPas, 75% deacetylation); (4) phosphate buffer solution (negative control); and (5) 0.5% chitosan (Ch 500 mPas, 75% deacetylation). CFU counting was performed for total microorganism, total streptococcus, total lactobacillus and Streptococcus mutans. Enamel demineralization was measured by transverse microradiography-TMR. The data were compared using ANOVA/Tukey or Kruskal-Wallis/Dunn tests (p < .050). ResultsNo differences were found between the treatments with respect to CFU counting (ANOVA, p > .050). Enamel treated with TiF4/NaF plus chitosan solution presented the lowest demineralization compared to the negative control and pure chitosan solution. On the other hand, this experimental solution did not significantly differ from TiF4/NaF and NaF solutions, being all of them able to significantly reduce mineral loss (50–74%), but only TiF4/NaF plus chitosan reduced lesion depth (55%) compared to the negative control (p = .001). ConclusionTiF4/NaF plus chitosan solution had no antimicrobial effect, but it was able to reduce enamel caries development in 79% compared to control under this model. Clinical significanceThis study showed that TiF4/NaF plus chitosan solution had no antimicrobial effect, but it was able to reduce enamel caries development under a microcosm biofilm model.

Efficacy of Ebselen Against Invasive Aspergillosis in a Murine Model.

Invasive aspergillosis is one of the major causes of morbidity and mortality among invasive fungal infections. The search for new antifungal drugs becomes imperative when existing drugs are not able to efficiently treat these infections. Ebselen, is an organoselenium compound, already successfully approved in clinical trials as a repositioned drug for the treatment of bipolar disorder and prevention of noise-induced hearing loss. In this study, we aimed to reposition ebselen for the treatment of invasive aspergillosis by showing ebselen effectiveness in a murine model. For this, BALB/c mice were immunosuppressed and infected systemically with Aspergillus fumigatus. Animals were divided and treated with ebselen, voriconazole, or drug-free control, for four days. The kidneys were used for CFU count and, histopathological and cytokine analysis. Ebselen was able to significantly reduce the fungal burden in the kidneys of infected mice with efficacy comparable with voriconazole treatment as both had reductions to the same extent. The absence of hyphae and intact kidney tissue structure observed in the histopathological sections analyzed from treated groups corroborate with the downregulation of IL-6 and TNF. In summary, this study brings for the first time in vivo evidence of ebselen efficacy against invasive aspergillosis. Despite these promising results, more animal studies are warranted to evaluate the potential role of ebselen as an alternative option for the management of invasive aspergillosis in humans.

The Combined Use of Gentamicin and Silver Nitrate in Bone Cement for a Synergistic and Extended Antibiotic Action against Gram-Positive and Gram-Negative Bacteria.

Using bone cement as a carrier, gentamicin was for years the default drug to locally treat orthopedic infections but has lost favor due to increasing bacterial resistance to this drug. The objective of this study was to investigate the effect of combining gentamicin with silver nitrate in bone cement against S. aureus and P. aeruginosa. Antibacterial effects (CFU counts) of gentamicin and silver were initially studied followed by studies using subtherapeutic concentrations of each in combination. The release rates from cement were measured over 10 days and day 7 release samples were saved and analyzed for antibiotic activity. A strong synergistic effect of combining silver with gentamicin was found using both dissolved drugs and using day 7 bone cement release media for both Gram-positive and Gram-negative bacteria. The cement studies were extended to vancomycin and tobramycin, which are also used in bone cement, and similar synergistic effects were found for day 7 release media with P. aeruginosa but not S. aureus. These studies conclude that the combined use of low loadings of gentamicin and silver nitrate in bone cement may offer an economical and much improved synergistic method of providing anti-infective orthopedic treatments in the clinic.