Microbicidal Effect Research Articles

Combating SARS-CoV-2: leveraging microbicidal experiences with other emerging/re-emerging viruses.

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Wuhan City, China, late in December 2019 is an example of an emerging zoonotic virus that threatens public health and international travel and commerce. When such a virus emerges, there is often insufficient specific information available on mechanisms of virus dissemination from animal-to-human or from person-to-person, on the level or route of infection transmissibility or of viral release in body secretions/excretions, and on the survival of virus in aerosols or on surfaces. The effectiveness of available virucidal agents and hygiene practices as interventions for disrupting the spread of infection and the associated diseases may not be clear for the emerging virus. In the present review, we suggest that approaches for infection prevention and control (IPAC) for SARS-CoV-2 and future emerging/re-emerging viruses can be invoked based on pre-existing data on microbicidal and hygiene effectiveness for related and unrelated enveloped viruses.

Preliminary Study: Comparative Analysis of the Effects of Ozone and Ultrasound on Streptococcus Mutans

ABSTRACT Streptococcus mutans is one of the principal pathogens of the human oral habitat, being one of the principal etiological agents of carious lesions. Ozone is a powerful oxidant, it has the ability to inactivate microorganisms in general, and ultrasound is an acoustic system generated through a piezoelectric crystal that also presents microbicidal effects. In the present study, a comparative analysis was made of the damage caused to Streptococcus mutans in vitro by ultrasound and ozone, through scanning electron microscopy (SEM) and atomic force microscopy (AF) analysis. In addition, flow cytometry was used to determine microbial viability and the formation of Reactive Oxygen Species (ROS) after the application of different techniques. The data obtained by means of microscopic analysis reveal that both ozone and ultrasound produce morphological alterations in bacteria, which become rod-shaped organisms. In addition to this deformation, on the microbial surface it was possible to identify crater-like impressions. In contrast, the irregularity of protuberances on the surface of the microbial wall was only detected when ozone was employed. Regarding the formation of ROS, it was observed that that ozone induces a significant growth (p < .05) of these molecules, while ultrasound does not present this effect. Ozone and ultrasound present microbicidal effects, however, ozone is more efficient.

A self-sterilizing fluorescent nanocomposite as versatile material with broad-spectrum antibiofilm features.

Hematogenous spread of infections from colonized central intravenous catheters or central lines is a long-recognized problem with infection rates of 2 and 6.8 per 1000days, respectively. Besides, removal of severe microbial colonization of implanted biomaterials is still a challenge and usually requires invasive operations. Hence, on demand self-sterilizing materials are required to avoid explant of colonized biomaterials and improve patient compliance. Moreover, photoluminescence is needed to make trackable biomaterials, which can be easily monitored upon implanting them in the body. Here, we propose the incorporation of near infrared (NIR) sensitive red-emitting carbon nanodot (CDs) into a polymeric matrix to give rise to innovative biomaterials with self-tracking and photothermal antimicrobial abilities. We obtain a material which can be processed to obtain medical devices using different techniques, among which, for instance, electrospinning. Herein, a proof-of-concept preparation of electrospun scaffolds is reported as it is highly desired in biomedical applications. Beside to confer imaging properties to the scaffold, that would allow an easy control over the in vivo positioning of implanted biomaterials as well as its degradation state and grade of integration with the surrounding native tissues, thanks to the capability to convert NIR light into local heat CDs can be exploited to exert broad-spectrum antimicrobial effect toward several pathogens. The rise in temperature can be easily modulated by controlling the irradiation time to achieve both an in vitro self-sterilization of the device and eventually in vivo destabilization of the microbial colonization. This innovative biomaterial could successfully inhibit biofilm formation and might be used as a powerful tool to treat antibiotic-resistant nature of biofilm-related infections in implanted medical devices.

Microbicidal effectiveness of irradiation from Gamma and X-ray sources at different dose rates against the foodborne illness pathogens Escherichia coli, Salmonella Typhimurium and Listeria monocytogenes in rice

The radiation response of three foodborne illness pathogens was examined for irradiation with cobalt-60 Gamma and low-energy (125 keV) X-ray at different dose rates. Escherichia coli, Salmonella Typhimurium and Listeria monocytogenes were inoculated into rice and irradiated at target doses of 0 (control), 250, 500, 750, 1000, and 1500 Gy with either Gamma radiation (dose rates of 9.1, 3.9 or 0.22 kGy/h) or X-ray radiation (dose rate of 0.76 kGy/h). Doses were measured with traceability to national standards. The dose rate did not significantly affect D10 values (microbicidal effectiveness) for any of the Gamma-irradiated pathogens. Low energy X-ray irradiated pathogens had significantly higher D10 values (lower microbicidal effectiveness) for all pathogens compared to Gamma-irradiated pathogens. The combination of Gamma or X-ray irradiation with a mixture of oregano/thyme essential oil (EO) fumigation generally increased the microbicidal effectiveness compared to irradiation alone. Gamma or low energy X-ray irradiation and plant essential oils such as oregano/thyme, applied alone or in combination, are effective antimicrobial treatments.

In vitro antimicrobial activity of hydrosol from Litsea cubeba (Lour.) Pers. against Helicobacter pylori and Candida albicans

Introduction: Helicobacter pylori and Candida albicans are classified as the most common pathogenic agents in humans. H. pylori is responsible for gastroduodenal diseases and greatly associated with gastric carcinogenesis, while C. albicans is the main cause of fungal urinary tract, genital yeast, and fungal skin infections. The increasing appearance of drug-resistant strains of H. pylori and C. albicans has made the treatment of the infections more serious. Hydrosols from plant steam distillation have been traditionally used in medicine, cosmetics, and culinary uses. They have been recently suggested as antimicrobial agents owing to their safety and ability to reduce the potential of resistance. The aim of the present study is to assess antibacterial and antifungal activities of hydrosols extracted from the fresh fruits of Litsea cubeba against H. pylori and C. albicans.&#x0D; Methods: The L. cubeba fruit hydrosol was obtained by steam distillation method. Evaluation of the growth-inhibiting and microbicidal effects of the hydrosol towards the H. pylori ATCC 43504 and C. albicans ATCC 10231 was determined through MIC (minimal inhibitory concentration), MBC (minimal bactericidal concentration), and MFC (minimal fungicidal concentration) measurements using broth dilution assays. Compositions of the dissolved essential oil (dEO) from the hydrosol were analyzed by GC-MS (gas chromatography-mass spectrometry).&#x0D; Results: The results indicated that the L. cubeba fruit hydrosol exhibited strong antimicrobial ability towards the bacterium H. pylori (MIC of 10%, MBC of 30%) and the yeast C. albicans (MIC of 10%, MFC of 40%). The cells of H. pylori and C. albicans were killed completely after 24 and 18 hours of treatment with 30% and 40% of the hydrosol, respectively. The major constituents of the dEO were geranial (32.92%), neral (27.12%), p-menthan-8-yl acetate (8.45%), 2-cyclopropyl-2-methylspiro[2.2]pentane-1-carboxylic acid (8.09%), linalool (4.24%), and methyl heptenone (4.15%).&#x0D; Conclusion: The results of the study suggest that L. cubeba fruit hydrosols could be used as potent natural antibacterial and antifungal preparations in the global effort to discover safe alternatives to toxic antimicrobial agents.&#x0D;

Cupric ion in combination with hydrogen peroxide and hydroxylamine applied to inactivation of different microorganisms

The microbial inactivation by cupric ion (Cu(II)) in combination with hydrogen peroxide (H2O2) and hydroxylamine (HA) was investigated for twelve different microorganisms (five Gram-negative bacteria, three Gram-positive bacteria, and four bacteriophages). The inactivation efficacy, protein oxidation, and RNA (or DNA) damage were monitored during and after treatment by Cu(II), Cu(II)/HA, Cu(II)/H2O2 and Cu(II)/HA/H2O2. The rate of microbial inactivation by the (combined) microbicides generally increased in the order of Cu(II) < Cu(II)/H2O2 < Cu(II)/HA < Cu(II)/HA/H2O2; Cu(II)/HA/H2O2 resulted in 0.18–0.31, 0.10–0.18, and 0.55–3.83 log inactivation/min for Gram-negative bacteria, Gram-positive bacteria, and bacteriophages, respectively. The degrees of protein oxidation and RNA (or DNA) damage increased in the order of Cu(II) < Cu(II)/HA < Cu(II)/H2O2 < Cu(II)/HA/H2O2. In particular, Cu(II)/HA/H2O2 led to exceptionally fast inactivation of the viruses. Gram-positive bacteria tended to show higher resistance to microbicides than other microbial species. The microbicidal effects of the combined microbicides on the target microorganisms were explained by the roles of Cu(I) and Cu(III) generated by the redox reactions of Cu(II) with H2O2, HA, and oxygen. Major findings of this study indicate that Cu(II)-based combined microbicides are promising disinfectants for different waters contaminated by pathogenic microorganisms.

Biophysical insights into the interaction of human serum albumin with Cassia fistula leaf extracts inspired biogenic potent antibacterial and anticancerous gold nanoparticles

In the present investigation, the characterization of Cassia fistula leaf extracts (CFLE) mediated gold nanoparticles (CF-GNPs) and its binding features with human serum albumin (HSA) through interaction have been probed. The results from UV-visible, TEM and EDX analysis proved the formation of CF-GNPs. The functional groups like OH, NH, CN etc present in the phytochemicals of CFLE were mainly acted as reducing and protecting agent which was confirmed by FTIR study. The zeta potential (−17.8 mV) and hydrodynamic size (20.4 nm) of the CF-GNPs were also measured by DLS. The microbicidal effect of the CF-GNPs was estimated against gram negative bacterium, Escherichia coli (DH5-Alpha) and MIC was found to be 2.8 nM. Anticancer activity of the CF-GNPs was also checked against A375 (skin melanoma) cell lines where IC50 was 6.5 nM. The interaction study of CF-GNPs with HSA and conformational alteration of HSA upon interaction were investigated by the fluorescence, lifetime, synchronous, circular dichroism spectrum and zeta potential measurement. The negative value of Gibb’s free energy indicated spontaneity of the CF-GNPs-HSA complex formation. The fluorescence lifetime measurement confirmed the construction of ground state CF-GNPs-HSA complex passing through static quenching mechanism and determined the distance from donor to acceptor also. Circular dichroism spectroscopy signified unchangeable native structure of HSA with minor decrease of alpha helix structure (54.5% to 51.1%) upon interaction. The more negative zeta potential value (−25.9 mV) of CF-GNPs-HSA system than the CF-GNPs (−17.8 mV) proved the adsorption of HSA on the outer surface of CF-GNPs. Communicated by Ramaswamy H. Sarma

Effect of pilot-scale UV-C light treatment assisted by mild heat on E. coli, L. plantarum and S. cerevisiae inactivation in clear and turbid fruit juices. Storage study of surviving populations

Consumer growing demands for high-quality and safe food and beverages have stimulated the interest in alternative preservation technologies. Short-wavelength ultraviolet light (UV-C, 254 nm) has proven to be useful for the decontamination of a great variety of clear juices while improving their quality compared to traditional thermal treatments. Suspended solids and coloured compounds in turbid juices, diminish light transmission. The use of UV-C under a hurdle approach, may be a promising strategy for their treatment. The purpose of this study was to analyse Escherichia coli ATCC 25922, Saccharomyces cerevisiae KE 162 and Lactobacillus plantarum ATCC 8014 inactivation in clear pear juice (PJ), turbid orange-tangerine (OT) and orange-banana-mango-kiwi-strawberry (OBMKS) juices processed by single UV-C (390 mJ/cm2, 20 °C) and UV-C assisted by mild heat (UV-C/H, 50 °C) at pilot-scale in a coiled tubing unit and stored under refrigeration (5 °C). Inactivation studies were also conducted in peptone water (PW) and model solution (MS). The adequacy of the Coroller, Weibull and Biphasic Plus Shoulder models was studied. UV-C was highly effective in PW, MS and PJ, achieving up to 5.5-6.3-4.7, 4.8-5.1-4.6 and 4.4-5.5 log reductions for L. plantarum, E. coli,and S. cerevisiae, respectively. Whereas, a moderate inactivation by single UV-C was recorded in the turbid blends, reducing up to 2.4-3.8-1.6 and 3.6-3.7-1.3 log-cycles in OT and OBMKS, respectively. When the UV-C/H treatment was applied, high bacterial inactivation was observed achieving 5.2-5.6, 6.3-6.6 and 5.5-6.7 log reductions in OT, OBMKS and PJ, respectively, while 4.6-4.9 log reductions were determined for the yeast in OBMKS and OT, respectively. Thus, additive inactivation effects between UV-C and H were observed. All the models tested gave useful information regarding the existence of microbial subpopulations with varying resistances. However, the cumulative Weibull distribution function was the most versatile one, fitting inactivation curves with different shapes. Additionally, the frequency distributions of resistances showed that UV-C/H not only increased the UV-C microbicidal effect but changed the distribution of inactivation times. Principal component analysis revealed that UV-C effectiveness was associated to low particle size, a⃰, turbidity and high UV-C transmittance. An increase on the inactivation of treated bacterial populations was recorded along storage, while no yeast recovery was observed, thus emphasizing the contribution of refrigerated storage to microbial inactivation. Microbial inactivation in clear and turbid juices achieved by UV-C (390 mJ/cm2) assisted by mild heat (50 °C) and subsequent refrigerated storage may represent an useful alternative for multiple applications in the juice industry.

Modulation of the Drug Resistance by Platonia insignis Mart. Extract, Ethyl Acetate Fraction and Morelloflavone/Volkensiflavone (Biflavonoids) in Staphylococcus aureus Strains Overexpressing Efflux Pump Genes.

Microbial resistance to antibiotics is a global public health problem, which requires urgent attention. Platonia insignis is a native species from the eastern Brazilian Amazon, used in the treatment of burns and wounds. To evaluate the antimicrobial activity of the hydroalcoholic extract of P. insignis (PIHA), the ethyl acetate fraction (PIAE), and its subfraction containing a mixture of biflavonoids (BF). Moreover, the effect of these natural products on the antibiotic activity against S. aureus strains overexpressing efflux pump genes was also evaluated. Minimal inhibitory concentrations were determined against different species of microorganisms. To evaluate the modulatory effect on the Norfloxacin-resistance, the MIC of this antibiotic was determined in the absence and presence of the natural products at subinhibitory concentrations. Inhibition of the EtBr efflux assays were conducted in the absence or presence of natural products. PIHA showed a microbicidal effect against S. aureus and C. albicans, while PIAE was bacteriostatic for S. aureus. PIAE and BF at subinhibitory concentrations were able to reduce the MIC of Norfloxacin acting as modulating agents. BF was able to inhibit the efflux of EtBr efflux in S. aureus strains overexpressing specific efflux pump genes. P. inignisis, a source of efflux pump inhibitors, including volkensiflavone and morelloflavone, which were able to potentiate the Norfloxacin activity by NorA inhibition, being also able to inhibit QacA/B, TetK and MsrA. Volkensiflavone and morelloflavone could be used as an adjuvant in the antibiotic therapy of multidrug resistant S. aureus strains overexpressing efflux pumps.

Effectiveness of vaginal microbicides in preventing HIV transmission.

To evaluate the evidence on the effectiveness of vaginal microbicides in preventing HIV transmission in women. Systematic review through a comprehensive search of relevant electronic databases for eligible randomised controlled trials (RCTs) published through June 2019. Two authors independently screened titles and abstracts according to eligibility criteria, then extracted data and assessed risk of bias of included studies. We conducted a random-effects meta-analysis of risk ratios (RR) of HIV infection and assessed heterogeneity using chi-squared and I2 tests. Sources of heterogeneity were investigated through subgroup analysis, publication bias was assessed using funnel plots, and certainty of evidence was graded using GRADEPro software. We included 18 RCTs which enrolled 40,048 sexually active, HIV-negative, non-pregnant women, aged 16years and older, mainly from sub-Saharan Africa. The intravaginal ring containing dapivirine significantly reduced HIV risk by 29% (RR 0.71, 95% CI: 0.57-0.89; 2 RCTs, 4,564 women, moderate certainty of evidence). Estimates of effect of tenofovir 1% (RR 0.83, 95% CI: 0.65-1.06), nonoxynol-9 (RR 1.15, 95% CI: 0.93-1.42), cellulose sulphate (RR 1.16, 95% CI: 0.61-2.21), SAVVY (RR 1.34, 95% CI: 0.69-2.59), Carraguard (RR 0.89, 95% CI: 0.71-1.10), BufferGel (RR 1.02, 95% CI: 0.71-1.46), 0.5% PRO2000 (RR 0.88, 95% CI: 0.60-1.28) and 2% PRO2000 (RR 0.81, 95% CI: 0.58-1.12) failed to reach statistical significance; each had low certainty of evidence. The long-acting intravaginal ring containing dapivirine significantly reduced risk of HIV transmission in women by 29%. The remaining microbicides had no evident effect.

Effectiveness of commonly used high level disinfectants on bacteria responsible for hospital acquired infections in Sri Jayewardenepura General Hospital, Sri Lanka

Introduction: Hospital-acquired infections (HAIs) cause high morbidity and mortality in patients throughout the world. Nosocomial pathogens can be transmitted through contaminated instruments and surfaces. Disinfectants play a crucial role in preventing HAIs. This study focuses on two high level disinfectants designated ‘disinfectant 1’ which contains primarily peracetic acid and ‘disinfectant 2’ which contains primarily didecyldimethylammonium chloride. Objective: To determine the effectiveness of commonly used high level disinfectants on bacteria responsible for causing HAIs in Sri Jayewardenepura General Hospital, Sri Lanka (SJGH), on different surfaces. Method: Data of the Infection Prevention and Control (IPC) unit of SJGH was traced back to identify bacteria causing HAIs from 1st January to 31st July 2018. This experimental study was conducted for disinfectant 1 and 2 according to the quantitative carrier test (European Standard EN 14561:2006). Disinfectants were tested at three different concentrations on glass, stainless steel and rexine surfaces against the commonest three bacteria responsible for causing HAIs in SJGH. Results: Coliforms, Acinetobacter species and Staphylococcus aureus were the three most common bacteria responsible for causing HAIs in SGJH. Surgical site infections were the predominant type of HAI and Intensive Care Units (ICUs) were identified as having the highest prevalence of HAIs. Both high level disinfectants achieved a Microbicidal Effect (ME) value of 5 as per ‘clean disinfectants’ in manufacturer recommended dilutions and passed the test against Escherichia coli, Acinetobacter spp. and S. aureus under both clean and dirty condition on all three tested surfaces. However, bacterial colonies of all 3 test organisms were detected after both disinfectant 1 and 2 use . Effect of disinfectant 1 was poor in manufacturer recommended concentrations on glass, stainless steel and rexine surfaces. ME of disinfectant 2 was considerably higher when compared to disinfectant 1. Conclusion: Although the manufacturer stated test standard was achieved for both disinfectants, the presence of residual bacteria after high level disinfectant use on different surfaces is not acceptable.

High microbicidal effect of peroxynitric acid on biofilm-infected dentin in a root carious tooth model and verification of tissue safety

ObjectivesRoot-caries, which frequently occurs in elderly people, is more difficult to treat than caries in a tooth crown, especially in filling restorations. To overcome this difficulty, it is essential to find a strategy for sufficiently sterilizing the infected dentin; however, techniques for sterilizing carious pathogens inside the biofilm, called dental plaque, have not yet been established. Recently, dental applications of plasma sterilization technology have attracted attention. The mechanism of plasma sterilization became clear, and revealed that peroxynitric acid (PNA) is an effective sterilization substance. Highly concentrated PNA solutions can be chemically synthesized in large quantities without using plasma technology. We thought that the application of PNA solution could be a novel treatment for root caries, and examined the microbicidal effect and safety of PNA. MethodsA sterilization experiment was performed using an extracted tooth model infected with Streptococcus mutans. Subsequently, a biofilm of S. mutans and Candida albicans was formed on a plate or a dentin slice, and sterilization experiments were performed in comparison with chlorhexidine. Furthermore, a toxicity test of PNA was performed using an epithelial tissue model. ResultsIn the infection model, sterilization was achieved with a 22 mM PNA solution in only 10 s. In the biofilm model, a 22 mM PNA solution showed a higher microbicidal effect than 2.0% chlorhexidine. In the toxicity test, 2.0% chlorhexidine was toxic, but a 220 mM PNA solution showed no toxicity. ConclusionsPNA is an unprecedented disinfectant that has high microbicidal activity on biofilm and is safe for tissues.

Stabilized hypochlorous acid, a topical therapeutic strategy for Trichomonas vaginalis infection: An in vitro study

Background: Trichomonas vaginalis (TV) parasitic protozoan is a widespread sexually transmitted infection. It is emphasized by the World Health Organization that the global prevalence of TV is rising. The parasite causes infections in the urogenital system in humans, and recently it was determined that it has a potential effect on both prostate and cervical cancer. Due to its being a significant public health problem, new treatment methods need to be developed to combat the parasite. Objective: Previous studies on the use of stabilized hypochlorous acid (HOCl) indicated that it has a potential microbicidal effect on different types of microorganisms. From this point, we investigated the effect of stabilized HOCl on TV in vitro. Material and Methods: Direct microscopy for time-kill (TK) assay, and vital trypan blue assay were performed to determinate the effective dose (1/2 to 1/64 dilution) and time (0 to 90 min) of stabilized HOCl action on live TV. For negative controls, sterile PBS alone was added to TV and medium. Results: The death of TV was dose and time dependent. Parasites were killed at a dilution of 1/2 and 1/4 at 0 min and for the rest of the time courses at these dilutions. Whereas, decreased effect was observed on TV viability with dilutions of 1/8,1/16 and 1/32 with different time courses and there was no effect at a dilution of 1/64. Conclusions: According to our findings, stabilized HOCl has an effect on TV viability and this is the first study on the effect of HOCl on TV.

Efeito microbicida do ozônio gasoso em Pseudomonas aeruginosa, Staphylococcus aureus e Candida albicans

Objetivo: Avaliar o efeito microbicida do ozônio gasoso em diferentes concentrações e tempos perante aos micro-organismos patogênicos: Pseudomonas aeruginosa, Staphylococcus aureus e Candida albicans cultivadas em placas de Petri. Material e Métodos: O efeito do gás de ozônio perantes cepas padronizadas das bactérias Pseudomonas aeruginosa ATCC 27853 e Staphylococcus aureus ATCC 25923 e da levedura Candida albicans ATCC 10231 foi testado em seis concentrações diferentes utilizando um gerador de ozônio. Gupo 1: sem tratamento; grupos experimentais com tratamento: de ozônio: Grupo 2: 60 µg/ml a 10 minutos, Grupo 3: 40 µg/ml a 10 minutos, Grupo 4: 30 µg/ml a 10 minutos, Grupo 5: 20 µg/ml a 5 minutos e Grupo 6: 15 µg/ml a 5 minutos, Os micro-oorganismos foram inoculados em placas de Petri com ágar sangue e em seguida receberam o gás de ozônio. Resultados: O gás de ozônio mostrou atividade antimicrobiana na maioria das concentrações utilizadas. Conclusão: O gás de ozônio mostrou uma atividade antimicrobiana valiosa contra os microorganismos testados. Uma aplicação tópica única por nebulização de cada concentração utilizada de ozono inibiu o crescimento da maioria das estirpes de bactérias potencialmente patogénicas com resistência conhecida a agentes antimicrobianos.

Advances of native and non-native Antarctic species to in vitro conservation: improvement of disinfection protocols

Plants that inhabit Antarctica have raised scientific interest due to their resilience to climate change, abiotic tolerance mechanisms and potential biological applications. In vitro propagation is useful for conservation, genetic material availability of these species and avoiding mass collection in their habitat. In vitro culture protocols for the native plants Colobanthus quitensis and Deschampsia antarctica and the non-native Juncus bufonius have been affected by endophytic microorganisms that proliferate when introduced to tissue cultures. This study evaluated the microbicidal and phytotoxic effect of calcium hypochlorite (Ca(ClO)2), silver nitrate (AgNO3) and silver nanoparticles (AgNPs), and their use at different concentrations for different time periods. The Ca(ClO)2 at 100 mg mL−1 showed the best microbial contamination control in D. antarctica (applied for 20 min) and for the three C. quitensis populations (applied for 15 min). In J. bufonius, AgNO3 at 10 mg mL−1 for 10 min reduced the microbial growth, but oxidative damage was generated. AgNPs did not prevent contamination or have adverse effects on tissues. Survival plantlets from each treatment, population or species were effectively introduced to the tissue culture and their propagation was successful. These results constitute a fundamental advance for the introduction, propagation and conservation of Antarctic species and their use in scientific research.

Chemical and Antioxidant Charaterization of Native Corn Germplasm from Two Regions of Costa Rica: A Conservation Approach.

The cultivation of native corn has decreased in favor of the cultivation of improved commercial corn varieties. This study seeks to evaluate the antioxidant and antibacterial potential of 36 samples of native corn germplasm from the Brunca (BR) and Chorotega (CR) regions of Costa Rica. The main parameters of comparison were the composition of antioxidant compounds, antiradical activity, and microbicidal effect. The total amount of polyphenols in the germplasm (120 mg GAE/100 g d.w.) was not related to the regions from which the samples were obtained. The overall average for antioxidant capacity was 21.20 μmol TE/g d.w. Accessions from the CR region had higher antioxidant capacity. Anthocyanin content was higher in purple accessions and undetectable in white germplasm. Antioxidant capacity was statistically related to polyphenols content (r = 0.714, p < 0.01). The most promising corn accessions in terms of nutraceutical value came from the CR region.

Antimicrobial efficacy of a very stable hypochlorous acid formula compared with other antiseptics used in treating wounds: in-vitro study on micro-organisms with or without biofilm

Many antiseptics have been used to treat wounds. To compare the microbicidal efficacy of ClHO (Clortech®) with other antiseptics used on wounds, healthy skin and mucous membranes. The microbicidal efficacy of 13 antiseptic products on eight micro-organisms (three Gram-positive; three Gram-negative; two yeasts) inoculated on organic germ-carriers was studied. In addition, the loss of efficacy against Staphylococcus aureus and Pseudomonas aeruginosa with biofilm was assessed with the six best-performing products. Chlorhexidine (1%) had the highest microbicidal effect at 1 min. At 5 min, 500 and 1500 mg/L ClHO showed similar, or better, activity than the other antiseptics studied. The ClHO concentration of 300 mg/L achieved this same efficacy at 10 min. The product that lost the most efficacy due to biofilm was 1% chlorhexidine, while 1% PVP-I and ClHO at either 300 or 500 mg/L were moderately affected by biofilm. The most effective in the presence of biofilm was ClHO at 1500 mg/L. ClHO at medium-low concentrations (300 or 500 mg/L) is a good antiseptic that can be used on wounds and mucous membranes for 5-10 min. Lower concentrations of ClHO, as well as of the other antiseptics studied, were less effective or more altered by the biofilm. ClHO at a concentration of 1500 mg/L is very effective in the presence or absence of biofilm that can be used on healthy skin for 5 min.

Effect of Selected Environmental Factors on the Microbicidal Effectiveness of Radiant Catalytic Ionization.

The aim of this study was the assessment of the effect of time exposure, temperature, distance, and organic contaminants on radiant catalytic ionization (RCI) microbicidal effectiveness. The number of all examined bacteria decreased together with time exposure of RCI. The lowest recovery was obtained, both from the rubber surface (6.36 log CFU × cm–2) and steel (6.04 log CFU × cm–2) in the case of Escherichia coli O157:H7. On the other hand, Staphylococcus aureus was isolated in the largest number (rubber: 7.88 log CFU × cm–2, steel: 7.79 log CFU × cm–2). Among the tested environmental conditions, the greatest bacterial population was re-isolated at 4°C (distance: 0.5 m, time: 24 h), whereas the lowest population was found at a distance of 0.5 m (temperature: 20°C, time: 24 h) and on surfaces without contamination. In the samples treated with RCI, the bacterial population was the lowest on non-contaminated surfaces, ranging from 3.76 log CFU × cm–2 (E. coli O157:H7) to 5.58 log CFU × cm–2 (S. aureus) for the rubber, and from 3.26 log CFU × cm–2 (E. coli O157:H7) to 5.20 log CFU × cm–2 (S. aureus) for the stainless steel. The highest bacteria number was isolated from surfaces contaminated with meat and fish pulp. The lowest bacterial reduction caused by RCI was found in the case of rubber contaminated with meat-fish pulp (24 h, 0.5 m, 20°C). The reduction rate was equal to 0.89 log CFU × cm–2 for S. aureus, 1.17 log CFU × cm–2 for Listeria monocytogenes, 1.43 log CFU × cm–2 for Salmonella Enteritidis and 1.61 log CFU × cm–2 for E. coli O157:H7. In turn, the greatest bacterial reduction was found in the case of non-contaminated steel (24 h, 0.5 m, 37°C). The reduction rate was equal to 4.52 log CFU × cm–2 for L. monocytogenes, 3.61 log CFU × cm–2 for S. Enteritidis, 2.98 log CFU × cm–2 for E. coli O157:H7 and 2.77 log CFU × cm–2 for S. aureus. RCI allows the inactivation of pathogens from stainless steel and rubber surfaces. Its efficacy is species-dependent and affected by environmental factors.

Fecal lactoferrin as a parameter in determining invasive causes of acute diarrhea

Introduction Diarrhea may be acute, which subsides by 7–14 days and is related to infections (bacterial or viral) or reaction to medications, or chronic, which lasts more than 2 weeks and is mainly caused by inflammatory bowel disease, functional bowel disorder, food allergies, or parasitic infestations. The infective etiologies may be noninvasive or invasive pathogens that have the capacity to invade intestinal mucosa and stimulate local inflammatory response [by activated neutrophils that secrete lactoferrin (LF)] and sometimes cause ulceration, hemorrhage, and systemic inflammatory response. Stool culture is the standard method for the diagnosis of invasive diarrhea; however, it is laborious and time consuming. LF is a major constituent of the secondary granules of neutrophils. It activates innate immunity and has microbicidal and anticancer effects. It is stable in feces for several days at room temperature and resistant to proteolysis. The presence of LF in the intestinal lumen is proportional to the flux of neutrophils, and its assessment can provide a reliable biomarker for inflammation and intestinal invasion. Aim The aim was to evaluate the clinical usefulness of fecal lactoferrin (FL) assay in differentiating invasive from noninvasive types of acute diarrhea. Patients and methods This cross-sectional study was performed on 90 children with acute diarrhea (≤1 week). Their ages ranged 4–168 months, with a mean of 48.18 ± 39.89 months. The patients were divided into two groups: group 1 included 31 patients with invasive diarrhea, and group 2 included 59 patients with noninvasive diarrhea. Results Serum C-reactive protein was significantly higher in group 1 than group 2 (28.46 and 9.7 mg/l, respectively; t = 2.7, P Conclusion FL testing is a good useful noninvasive test in differentiating invasive from noninvasive acute diarrhea.

Characterization of the silver thin films produced at different substrate temperatures

Introduction: In recent decades, the antimicrobial surfaces/coating properties towards a longlasting microbicidal effect have drawn enormous attention by researchers, they have been developed and used in a wide variety of high-touch hospital devices as a potential approach.&#x0D; Methods: In this work, Ag NPs was synthesized by sputtering method at the different annealing temperatures of 100◦C, 200◦C, 300◦C, and 400◦C.&#x0D; Results: As a result, the as-synthesized Ag-300 exhibits the highest E. coli antibacterial performance compared with others. This can be attributed to the change of the Ag NPs toxicity based on the growth of nanoparticles during the deposition process related to the Ostwald ripening process, thermal activation and coalescence particles.&#x0D; Conclusion: This work provides an essential insight into the antimicrobial activity of Ag NPs-based films synthesized through the vacuum deposition technique, resulting in opening a new approach for enhancing the antimicrobial efficacy and prospects.&#x0D; &#x0D;