Light, Copper, Action: Visible-Light Illumination Enhances Bactericidal Activity of Copper Particles.

Bacteria are an old concern to human health, as they are responsible for nosocomial infections, and the number of antibiotic-resistant microorganisms keeps growing. Copper is known for its intrinsic biocidal properties, and therefore, it is a promising material to combat infections when added to surfaces. However, its biocidal properties in the presence of light illumination have not been fully explored, especially regarding the use of microsized particles since nanoparticles have taken over all fields of research and subjugated microparticles despite them being abundant and less expensive. Thus, the present work studied the bactericidal properties of metallic copper particles, in microscale (CuMPs) and nanoscale (CuNPs), in the absence of light and under white LED light illumination. The minimum bactericidal concentration (MBC) of CuMPs against Staphylococcus aureus that achieved a 6-log reduction was 5.0 and 2.5 mg mL-1 for assays conducted in the absence of light and under light illumination, respectively. Similar behavior was observed against Escherichia coli. The bactericidal activity under illumination provided a percentage increase in log reduction values of 65.2% for S. aureus and 166.7% for E. coli when compared to the assays under dark. This assay reproduced the testing CuNPs, which showed superior bactericidal activity since the concentration of 2.5 mg mL-1 promoted a 6-log reduction of both bacteria even under dark. Its superior bactericidal activity, which overcame the effect of illumination, was expected once the nanoscale facilitated the interaction of copper within the surface of bacteria. The results from MBC were supported by fluorescence microscopy and atomic absorption spectroscopy. Therefore, CuMPs and CuNPs proved to have size- and dose-dependent biocidal activity. However, we have shown that CuMPs photoactivity is competitive compared to that of CuNPs, allowing their application as a self-cleaning material for disinfection processes assisted by conventional light sources without additives to contain the spread of pathogens.

Synergistic bactericidal combinations between gentamicin and chitosan capped ZnO nanoparticles: A promising strategy for repositioning this first-line antibiotic.

Gentamicin (GEN), a widely used broad-spectrum antibiotic, faces challenges amid the global emergency of antimicrobial resistance. This study aimed to explore the synergistic effects of zinc oxide nanoparticles (ZnO NPs) in combination with GEN on the bactericidal activity against various bacterial strains. Results showed ZnO NPs with MICs ranging from 0.002 to 1.5 µg/mL, while the precursor salt displayed a MIC range of 48.75-1560 µg/mL. Chitosan (CS)-capped ZnO NPs exhibited even lower MICs than their uncapped counterparts, with the CS-capped synthesized ZnO NPs demonstrating the lowest values. Minimal bactericidal concentrations (MBC) aligned with MIC trends. Combinations of CS-capped synthesized ZnO NPs and GEN proved highly effective, inhibiting bacterial growth at significantly lower concentrations than GEN or ZnO NPs alone. This phenomenon may be attributed to the conformation of CS on the ZnO NPs' surface, enhancing the positive particle surface charge. This possibly facilitates a more effective interaction between ZnO NPs and microorganisms, leading to increased accumulation of zinc and GEN within bacterial cells and an overproduction of reactive oxygen species (ROS). It's crucial to note that, while this study did not specifically involve resistant strains, its primary focus remains on enhancing the overall antimicrobial activity of gentamicin. The research aims to contribute to addressing the global challenge of antimicrobial resistance, recognizing the urgent need for effective strategies to combat this critical issue. The findings, particularly the observed synergy between ZnO NPs and GEN, hold significant implications for repositioning the first-line antibiotic GEN.

Litsea glaucescens Kuth possesses bactericidal activity against Listeria monocytogenes.

Background: Litsea glaucencens Kuth is an aromatic plant used for food seasoning food and in Mexican traditional medicine. Among, L. glaucencens leaves properties, it has proven antibacterial activity which can be used against opportunistic pathogens like Listeria monocytogenes, a foodborne bacteria that is the causal agent of listeriosis, a disease that can be fatal in susceptible individuals. The aim of this work was to investigate the antibacterial activity of L. glaucescens Kuth leaf extracts against L. monocytogenes and to identify its bioactive components. Material and Methods: L. glaucences leaves were macerated with four solvents of different polarity (n-hexane, dichloromethane, ethyl acetate, and methanol). To determine the capacity to inhibit bacterial proliferation in vitro, agar diffusion and microdilution methods were used. Next, we determined the minimal bactericidal concentration (MBC). Finally, we determined the ratio of MBC/MIC. Metabolites present in the active methanolic extract from L. glaucescens Kuth (LgMeOH) were purified by normal-phase open column chromatography. The structure of the antibacterial metabolite was determined using nuclear magnetic resonance (1H, 13C, COSY, HSQC) and by comparison with known compounds. Results: The LgMeOH extract was used to purify the compound responsible for the observed antimicrobial activity. This compound was identified as 5,7-dihydroxyflavanone (pinocembrin) by analysis of its spectroscopic data and comparison with those described. The MIC and MBC values obtained for pinocembrin were 0.68 mg/mL, and the ratio MBC/MIC for both LgMeOH and pinocembrin was one, which indicates bactericidal activity. Conclusion: L. glaucences Kuth leaves and its metabolite pinocembrin can be used to treat listeriosis due the bactericidal activity against L. monocytogenes.

Excretory-secretory products from adult helminth Nippostrongylus brasiliensis have in vitro bactericidal activity.

Introduction. Intestinal helminths and microbiota share the same anatomical niche during infection and are likely to interact either directly or indirectly. Whether intestinal helminths employ bactericidal strategies that influence their microbial environment is not completely understood.Hypothesis. In the present study, the hypothesis that the adult hookworm Nippostrongylus brasiliensis produces molecules that impair bacterial growth in vitro, is tested.Aim. To investigate the in vitro bactericidal activity of Nippostrongylus brasiliensis against commensal and pathogenic bacteria.Methodology. The bactericidal effect of somatic extract and excretory-secretory products of adult Nippostrongylus brasiliensis on Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli, Salmonella enterica serovar Typhimurium, and Klebsiella pneumoniae) bacteria was assessed using growth assays. Minimum inhibitory concentration and minimum bactericidal concentration assays were performed using excretory-secretory products released from the pathogen.Results. Broad-spectrum in vitro bactericidal activity in excretory-secretory products, but not somatic extract of adult Nippostrongylus brasiliensis was detected. The bactericidal activity of excretory-secretory products was concentration-dependent, maintained after heat treatment, and preserved after repeated freezing and thawing.Conclusion. The results of this study demonstrate that helminths such as Nippostrongylus brasiliensis release molecules via their excretory-secretory pathway that have broad-spectrum bactericidal activity. The mechanisms responsible for this bactericidal activity remain to be determined and further studies aimed at isolating and identifying active bactericidal molecules are needed.

Application of Silver Nanoparticles to Improve the Antibacterial Activity of Orthodontic Adhesives: An In Vitro Study.

There is a significant change in the bacterial plaque populations in the oral cavity during and after orthodontic treatment. Numerous studies have demonstrated that 2−96% of patients could increase the risk of white spot lesions. Streptococcus mutans and Lactobacilli ssp. are responsible for these white spot lesions. In this work, silver nanoparticles (AgNPs) with a diameter of 11 nm and dispersed in water were impregnated onto three different commercial orthodontic adhesives at 535 µg/mL. The shear bond strength (SBS) was assessed on 180 human premolars and metallic brackets. The premolars were divided into six groups (three groups for the commercial adhesives and three groups for the adhesives with AgNPs). All the groups were tested for their bactericidal properties, and their MIC, MBC, and agar template diffusion assays were measured. After adding AgNPs, the SBS was not significantly modified for any adhesive (p > 0.05), and the forces measured during the SBS did not exceed the threshold of 6 to 8 MPa for clinical acceptability in all groups. An increase in the bactericidal properties against both S. mutans and L. acidophilus was measured when the adhesives were supplemented with AgNPs. It was concluded that AgNPs can be supplement commercial orthodontic adhesives without modifying their mechanical properties with improved bactericidal activity.

Photobiological effect of eugenol-derived 3-benzoylcoumarin associated with led lights against MDR microorganisms.

The problem of antibiotic resistance by bacteria threatens human health. Therefore, studies in this area seek alternatives to circumvent it. The study with coumarins and eugenol has already proven that these classes of compounds act against bacteria. In this same aspect, exposure to LED also shows a bactericidal effect. Seeking a possible enhancement of this effect, the present work studied coumarins derived from eugenol in association with LED to investigate the bactericidal effect. Four compounds were tested. For this, minimum inhibitory concentrations (MICs) and modulation with three antibiotics against Escherichia coli and Staphylococcus aureus bacteria were determined. To test the behavior of the activity against exposure to LED, the plates were exposed for 20 min to blue light, 415 nm and then incubated at 37°C for 24 h. For control, duplicates were made, and one of them did not undergo this exposure. C1 exhibited better activity against S. aureus, as synergism prevailed under the conditions tested. C3 and C4 were promising against E. coli as they showed synergism in association with the three antibiotics both with and without LED exposure. Thus, the compounds showed bactericidal activity, and LED was shown to enhance synergism.

Evaluation of collision/reaction gases in single-particle ICP-MS for sizing selenium nanoparticles and assessment of their antibacterial activity.

Selenium nanoparticles (SeNPs) have recently attracted attention because they combine the benefits of Se and lower toxicity compared to other chemical forms of this element. In this study, SeNPs were synthesized by a green method using ascorbic acid as the reducing agent and polyvinyl alcohol as stabilizer. The nanoparticles were widely characterized. To determine the total concentration of Se by ICP-MS, several isotopes and the use of He as collision gas were evaluated, which was effective in minimizing interferences. A method for sizing SeNPs by single particle ICP-MS (SP-ICP-MS) was developed. For this purpose, He and H2were evaluated as collision/reaction gases, and the second one showed promising results, providing an average diameter of 48 nm for the SeNPs. These results agree with those obtained by TEM (50.1 nm). Therefore, the SP-ICP-MS can be implemented for characterizing SeNPs in terms of size and size distribution, being an important analytical tool for Se and other widely studied nanoparticles (e.g. Ag, Au, Ce, Cu, Fe, Zn). Finally, the antibacterial activity of SeNPs was assessed. The SeNPs showed bacteriostatic activity against three strains of Gram-positive bacteria and were particularly efficient in inhibiting the growthE. faecaliseven at very low concentrations (MIC < 1.4 mg l-1). In addition, a bactericidal activity of SeNPs againstS. aureuswas observed. These nanoparticles may have potential application in pharmaceutical industry, biomedicine and agriculture.

Current Status of Endolysin-Based Treatments against Gram-Negative Bacteria.

The prevalence of multidrug-resistant Gram-negative bacteria is a public health concern. Bacteriophages and bacteriophage-derived lytic enzymes have been studied in response to the emergence of multidrug-resistant bacteria. The availability of tRNAs and endolysin toxicity during recombinant protein expression is circumvented by codon optimization and lower expression levels using inducible pET-type plasmids and controlled cultivation conditions, respectively. The use of polyhistidine tags facilitates endolysin purification and alters antimicrobial activity. Outer membrane permeabilizers, such as organic acids, act synergistically with endolysins, but some endolysins permeate the outer membrane of Gram-negative bacteria per se. However, the outer membrane permeation mechanisms of endolysins remain unclear. Other strategies, such as the co-administration of endolysins with polymyxins, silver nanoparticles, and liposomes confer additional outer membrane permeation. Engineered endolysins comprising domains for outer membrane permeation is also a strategy used to overcome the current challenges on the control of multidrug-resistant Gram-negative bacteria. Metagenomics is a new strategy for screening endolysins with interesting antimicrobial properties from uncultured phage genomes. Here, we review the current state of the art on the heterologous expression of endolysin, showing the potential of bacteriophage endolysins in controlling bacterial infections.

Molecular epidemiology of cefotaxime-resistant but ceftazidime-susceptible Enterobacterales and evaluation of the in vitro bactericidal activity of ceftazidime and cefepime.

Extended-spectrum ß-lactamases' (ESBLs) production is the main resistance mechanism to third-generation cephalosporins (TGCs) in gram-negative bacilli. In Argentina, there is a high prevalence of cefotaximase-type ESBLs (CTX-M). For this reason, dissociated resistance phenotype (DRP) displaying a profile of resistance to cefotaxime (CTX) and susceptibility to ceftazidime (CAZ) might be detected. The aims of this study were to determine the prevalence of DRP in Enterobacterales clinical isolates, to characterize the mechanisms responsible for this phenotype and to evaluate the in vitro behaviour against different antibiotics. Sixty Enterobacterales resistant to any TGC were studied, and among them, 25% displayed a DRP. The ß-lactamases associated with DRP were 5/11 CTX-M-2, 4/11 CTX-M-14, 1/11 CTX-M-15 and 1/11 CMY-2 in E. coli, 2/3 CTX-M-2 and 1/3 CMY-2 in P. mirabilis and 1/1 CTX-M-14 in K. pneumoniae. Furthermore, CTX-M-2 and CTX-M-14 were related with DRP in both wild-type isolates and the corresponding transconjugants. Time-kill experiments showed CAZ bactericidal activity on CTX-M-2-and CTX-M-14-producing strains and bacterial regrowth in those CMY-2 producers. An opposite behaviour was evident when cefepime (FEP) was used. However, CAZ and gentamicin combination showed a synergistic effect against the CMY-2 producers. We concluded that Enterobacterales with DRP responded differently to CAZ or FEP depending on the type of ß-lactamase they possess, suggesting that these cephalosporins could be a therapeutic option. Therefore, the characterization of the involved resistance mechanism might contribute to define the appropriate antibiotic treatment.

In vitro bactericidal activity of a carbohydrate polymer with zinc oxide for the treatment of chronic wounds.

Introduction. Biological adhesives and effective topical therapeutic agents that improve wound healing are urgently required for the treatment of chronic ulcers. A biodegradable adhesive based on a carbohydrate polymer with zinc oxide (CPZO) was shown to possess anti-inflammatory activity and enhance wound healing, but its bactericidal activity was unknown.Aim. To investigate the bactericidal activity of CPZO against bacteria commonly present as infectious agents in chronic wounds.Methodology. We examined the bactericidal activity of CPZO against three biofilm-producing bacteria (Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa) through three strategies: bacterial suspension, biofilm disruption and in vitro wound biofilm model.Results. In suspension cultures, CPZO had direct, potent bactericidal action against S. aureus within 24 h, whereas E. coli took 7 days to be eliminated. By contrast, P. aeruginosa survived up to 14 days with CPZO. CPZO had biofilm disruption activity against clinical isolates of S. aureus in the anti-biofilm test. Finally, in the in vitro wound biofilm model, CPZO dramatically reduced the bacterial viability of S. aureus and P. aeruginosa.Conclusions. Together with its previously shown anti-inflammatory properties, the bactericidal activity of CPZO gives it the potential to be a first-line therapeutic option for chronic various ulcers and, possibly, other chronic ulcers, preventing or controlling microbial infections, and leading to the healing of such complicated chronic ulcers.

Early Bactericidal Activity Trial of Nitazoxanide for Pulmonary Tuberculosis.

This study was conducted in treatment-naive adults with drug-susceptible pulmonary tuberculosis in Port-au-Prince, Haiti, to assess the safety, bactericidal activity, and pharmacokinetics of nitazoxanide (NTZ). This was a prospective phase II clinical trial in 30 adults with pulmonary tuberculosis. Twenty participants received 1 g of NTZ orally twice daily for 14 days. A control group of 10 participants received standard therapy over 14 days. The primary outcome was the change in time to culture positivity (TTP) in an automated liquid culture system. The most common adverse events seen in the NTZ group were gastrointestinal complaints and headache. The mean change in TTP in sputum over 14 days in the NTZ group was 3.2 h ± 22.6 h and was not statistically significant (P = 0.56). The mean change in TTP in the standard therapy group was significantly increased, at 134 h ± 45.2 h (P < 0.0001). The mean NTZ MIC for Mycobacterium tuberculosis isolates was 12.3 µg/ml; the mean NTZ maximum concentration (Cmax) in plasma was 10.2 µg/ml. Negligible NTZ levels were measured in sputum. At the doses used, NTZ did not show bactericidal activity against M. tuberculosis Plasma concentrations of NTZ were below the MIC, and its negligible accumulation in pulmonary sites may explain the lack of bactericidal activity. (This study has been registered at ClinicalTrials.gov under identifier NCT02684240.).

Microbicidal Dispersions and Coatings from Hybrid Nanoparticles of Poly (Methyl Methacrylate), Poly (Diallyl Dimethyl Ammonium) Chloride, Lipids, and Surfactants.

Hybrid and antimicrobial nanoparticles (NPs) of poly (methyl methacrylate) (PMMA) in the presence of poly (diallyl dimethyl ammonium) chloride (PDDA) were previously obtained by emulsion polymerization in absence of surfactant with low conversion. In the presence of amphiphiles such as cetyl trimethyl ammonium bromide (CTAB), dioctadecyl dimethyl ammonium bromide (DODAB) or soybean lecithin, we found that conversion increased substantially. In this work, the effect of the amphiphiles on the NPs core-shell structure and on the antimicrobial activity of the NPs was evaluated. NPs dispersions casted on silicon wafers, glass coverslips or polystyrene substrates were also used to obtain antimicrobial coatings. Methods for characterizing the dispersions and coatings were based on scanning electron microscopy, dynamic light scattering, determination of thickness, rugosity, and wettability for the coatings and determination of colony-forming unities (log CFU/mL) of microbia after 1 h interaction with the coatings or dispersions. The amphiphiles used during PMMA/PDDA/amphiphile NPs synthesis reduced the thickness of the NPs PDDA shell surrounding each particle. The antimicrobial activity of the dispersions and coatings were due to PDDA-the amphiphiles were either washed out by dialysis or remained in the PMMA polymeric core of the NPs. The most active NPs and coatings were those of PMMA/PDDA/CTAB-the corresponding coatings showed the highest rugosity and total surface area to interact with the microbes. The dispersions and coatings obtained by casting of the NPs dispersions onto silicon wafers were hydrophilic and exhibited microbicidal activity against Escherichia coli, Staphylococcus aureus, and Candida albicans. In addition, a major effect of reduction in particle size revealed the suitability of nanometric and cationic NPs (sizes below 100 nm) represented by PMMA/PDDA/CTAB NPs to yield maximal microbicidal activity from films and dispersions against all microbia tested. The reduction of cell viability by coatings and dispersions amounted to 6-8 logs from [PDDA] ≥ minimal microbicidal concentration.

In vitro growth inhibition and bactericidal activity of spathulenol against drug-resistant clinical isolates of Mycobacterium tuberculosis

ABSTRACT Spathulenol was isolated from an extract of Azorella compacta Phil., Apiaceae, by various chromatographic method; identification of the chemical structure was confirmed by comparing its spectroscopic data with those reported in the literature. The anti-Mycobacterium tuberculosis activity of spathulenol was evaluated on MDR, pre-XDR, and XDR clinical isolates of M. tuberculosis, as well as on the reference susceptible strain H37Rv and its cytotoxic activity was evaluated on the Vero Cell Line. The anti-M. tuberculosis activity of spathulenol was twice as potent against the MDR, pre-XDR, and XDR clinical isolates (6.25 µg/ml) than on the susceptible H37Rv strain (12.5 µg/ml). Additionally, the anti-M. tuberculosis activity shown by spathulenol was established as bactericidal on drug-resistant and susceptible strains of M. tuberculosis. Finally, cytotoxic activity on the Vero cell line (CC50 = 95.7 µg/ml) indicated that spathulenol is a selective anti-M. tuberculosis compound, with a selective index of 15.31 against drug-resistant clinical isolates of M. tuberculosis.

Probiotic properties and fatty acid composition of the yeast Kluyveromyces lactis M3. In vivo immunomodulatory activities in gilthead seabream (Sparus aurata).

The aim of this study was to analyze the probiotic potential, fatty acid composition and immunostimulant activities of Kluyveromyces lactis M3 isolated from a hypersaline sediment. For this purpose, K. lactis M3 resistance to different pH, salinities and bile, as well as its antioxidant capability were assayed. Furthermore, total fatty acid composition of the yeast was determined where the dominant fatty acids were palmitic, palmitoleic, oleic and linoleic acids. K. lactis M3 showed no cytotoxic effects on peripheral blood leukocytes. During an in vivo experiment in gilthead seabream (Sparus aurata), dietary K. lactis M3 supplemented at 0.55 or 1.1% of the basal diet enhanced bactericidal activity against Vibrio parahaemolyticus N16, V. harveyi Lg 16/00, and V. anguillarum CECT 43442 compared to fish fed commercial diet (control group). Finally, nitric oxide production, peroxidase activity and skin mucus lectin union levels strongly increased in fish fed K. lactis M3 with respect to the control group. The results suggested that the yeast K. lactis M3 had exhibited high antioxidant capability, and its dietary administration at 0.55 or 1% basal diet had immunostimulant activity for gilthead seabream. For all these reasons, it should be considered an appropriate probiotic candidate for the aquaculture fish industry.

Differentially Detectable Mycobacterium tuberculosis Cells in Sputum from Treatment-Naive Subjects in Haiti and Their Proportionate Increase after Initiation of Treatment.

Recent reports indicate that the sputum of 80% or more of treatment-naive subjects with tuberculosis recruited in England or South Africa contained more viable Mycobacterium tuberculosis cells detected by limiting dilution (LD) in liquid culture than detected as CFU. Efforts to generate such differentially detectable (DD) M. tuberculosis populations in vitro have been difficult to reproduce, and the LD assay is prone to artifact. Here, we applied a stringent version of the LD assay to sputum from 33 treatment-naive, HIV-negative Haitian subjects with drug-sensitive tuberculosis (TB) and to a second sputum sample after two weeks of standard treatment with isoniazid, rifampin, pyrazinamide, and ethambutol (HRZE) for 13 of these subjects. Twenty-one percent had statistically defined levels of DD M. tuberculosis in their pretreatment sputum at an average proportional excess over CFU of 3-fold. Sixty-nine percent of those who received HRZE had statistically defined levels of DD M. tuberculosis in their sputum, and of these, the mean proportionate excess over CFU was 7.9-fold. Thus, DD M. tuberculosis is detectable in pretreatment sputum from a significant proportion of subjects in the Western Hemisphere, and certain drugs or drug regimens, while reducing CFU, may at the same time increase the proportional representation of DD M. tuberculosis among the surviving bacilli. Monitoring DD M. tuberculosis may improve our ability to predict the efficacy of efforts to shorten treatment.IMPORTANCE Measurement of the reduction in CFU in sputum of patients with TB up to 2 weeks after the initiation of treatment is the gateway test for a new TB treatment. Reports have suggested that CFU assays fail to detect the majority of viable M. tuberculosis cells in sputum samples from the majority of patients when the number of M. tuberculosis is estimated by limiting dilution (LD). In an effort to avoid potential methodologic confounders, we applied a modified version of the LD assay in a study of a geographically distinct population. We confirmed that differentially detectable (DD) M. tuberculosis is often found before treatment, albeit at lower proportionate levels than in earlier reports. Strikingly, the prevalence and proportionate representation of DD M. tuberculosis increased during standard treatment. Sublethal exposure to certain antibiotics may help generate DD M. tuberculosis cells or enrich their representation among the surviving bacteria, and this may contribute to the need for prolonged treatment with those agents in order to achieve durable cures.

Usnic acid-loaded polyaniline/polyurethane foam wound dressing: preparation and bactericidal activity.

The improved bactericidal activity of new composites for wound dressing prototypes represents an important strategy for development of more efficient devices that make use of synergistic interaction between components. The doping level of polyaniline represents a critical parameter for its corresponding biologic activity. In this work, it is explored the doping effect of usnic acid on undoped polyaniline, that introduces important advantages namely, improved bactericidal activity of polyaniline and the anti-biofilm properties of lichen derivative. The deposition of the resulting material on polyurethane foam potentializes its applicability as wound dressing, characterizing a new platform for application against Escherichia coli and Staphylococcus aureus.

Inactivación in vitro de bacterias patógenas mediante el uso de ozono en diferentes tiempos de exposición / In vitro inactivation of pathogenic bacteria by the use of ozone in different exposure times

Intrdoduction: in the area of ​​health, ozone has many therapeutic properties. Several pathologies can be treated with ozone therapy, such as infectious, acute and chronic diseases caused by viruses, bacteria, fungi and parasites, autoimmune diseases, diseases with chronic ischemia, lung diseases, neuropathies, dermatological diseases, dental caries, among others. Objective: to evaluate the effect of ozone applied in vitro in the following strains: Escherichia coli CCCD E003, Salmonella enterica subsp. enterica serovar Typhi CCCD S009, Staphylococcus aureus CCCD S003, Pseudomonas aeruginosa CCCD P013, Streptococcus mutans ATCC 25175 and Enterococcus faecalis ATCC 18211. For this purpose use was made of different cell concentrations and different times of exposure to ozone. Methods: we used concentrations of 1 x 102, 1 x 103, 1 x 10 4, 1 x 105, 1 x 106, 1 x 107, 1 x 108 and 1 x 109 CFU/mL of NaCl (0.5 percent w/v) exposed to ozone for different time intervals (30, 60, 90, 120, 150, 180, 210, 240, 270, 300, 330, 360, 390, 420, 450, 480, 510 and 540 s). Bacterial viability was determined by CFU and the colorimetric method with 2,3,5-Triphenyltetrazolium Chloride. Results: it was found that the species S. aureus, E. coli, S. typhi, S. mutans and E. faecalis were sensitive to ozone, showing a decrease of 45-80 percent of viable cells after 30 s of ozone exposure relative to the initial population, whereas P. aeruginosa was reduced 25 percent compared to the initial population. The viability of bacteria exposed to ozone was dependent on the cell concentration and time exposure. Conclusions: ozone had a bactericidal effect on the bacteria used in this study and that this effect was proportional to the concentration of bacterial cells and the time of exposure to O3. The results show significant efficacy of ozone to control populations of pathogenic bacteria, providing relevant information for its use in different areas, but always taking into account the microorganism involved(AU)

Introducción: el ozono tiene muchas aplicaciones terapéuticas en la esfera de la salud. Algunas patologías pueden tratarse con ozonoterapia, entre ellas enfermedades infecciosas, agudas y crónicas causadas por virus, bacterias, hongos o parásitos, enfermedades autoinmunitarias, enfermedades con isquemia crónica, enfermedades pulmonares, neuropatías, enfermedades dermatológicas y caries dentales, entre otras. Objetivo: evaluar el efecto del ozono aplicado in vitro sobre las siguientes cepas: Escherichia coli CCCD E003, Salmonella enterica subesp. enterica serovar Typhi CCCD S009, Staphylococcus aureus CCCD S003, Pseudomonas aeruginosa CCCD P013, Streptococcus mutans ATCC 25175 y Enterococcus faecalis ATCC 18211. Con este propósito se utilizaron diferentes concentraciones celulares y diferentes tiempos de exposición al ozono. Métodos: utilizamos concentraciones de 1 x 102, 1 x 103, 1 x 104, 1 x 105, 1 x 106, 1 x 107, 1 x 108 y 1 x 109 UFC/mL de NaCl (0,5 por ciento m/v) expuestas a ozono durante diferentes intervalos de tiempo (30, 60, 90, 120, 150, 180, 210, 240, 270, 300, 330, 360, 390, 420, 450, 480, 510 y 540 s). La viabilidad bacteriana se determinó mediante UFC y el método colorimétrico con cloruro de 2,3,5-trifeniltetrazolio. Resultados: se observó que las especies S. aureus, E. coli, S. typhi, S. mutans y E. faecalis eran sensibles al ozono, mostrando una disminución de 45-80 por ciento de las células viables luego de una exposición de 30 s al ozono en comparación con la población inicial, mientras que la especie P. aeruginosa se redujo en un 25 por ciento en comparación con la población inicial. La viabilidad de las bacterias expuestas al ozono dependió tanto de la concentración celular como del tiempo de exposición. Conclusiones: el ozono mostró tener un efecto bactericida sobre las bacterias utilizadas en el estudio, y ese efecto fue proporcional tanto a la concentración de las células bacterianas como al tiempo de exposición al O3. Los resultados demuestran la significativa eficacia del ozono para controlar poblaciones de bacterias patógenas, y ofrecen información relevante con vistas a su uso en diferentes áreas, pero siempre teniendo en cuenta el microorganismo en cuestión(AU)

Cationic Biomimetic Particles of Polystyrene/Cationic Bilayer/Gramicidin for Optimal Bactericidal Activity.

Nanostructured particles of polystyrene sulfate (PSS) covered by a cationic lipid bilayer of dioctadecyldimethylammonium bromide (DODAB) incorporated gramicidin D (Gr) yielding optimal and broadened bactericidal activity against both Escherichia coli and Staphylococcus aureus. The adsorption of DODAB/Gr bilayer onto PSS nanoparticles (NPs) increased the zeta-average diameter by 8-10 nm, changed the zeta-potential of the NPs from negative to positive, and yielded a narrow size distributions for the PSS/DODAB/Gr NPs, which displayed broad and maximal microbicidal activity at very small concentrations of the antimicrobials, namely, 0.057 and 0.0057 mM DODAB and Gr, respectively. The results emphasized the advantages of highly-organized, nanostructured, and cationic particles to achieve hybrid combinations of antimicrobials with broad spectrum activity at considerably reduced DODAB and Gr concentrations.

Chemical composition and evaluation of the antibacterial and Cytotoxic activities of the essential oil from the leaves of Myracrodruon urundeuva.

BACKGROUND: This study evaluated the in vitro activity of essential oil extracted from the leaves of Myracrodruon urundeuva. METHODS: The oil was obtained by hydro-distillation and characterized by Gas Chromatography coupled to Mass Spectrometry (GC-MS) and Gas Chromatography with Flame Ionization Detector (GC-FID). The antibacterial activity was evaluated by the broth microdilution technique and the MIF was determined by using growth indicator CTT (2,3,5-triphenyl-tetrazolium) and CBM in BHI agar. The oil's cytotoxicity was evaluated in HeLa, HEK-293, and Vero E6 cells using MTT, 3- (4,5-dimethylthiazol-2-yl) -2,5-diphenyl tetrazolium. RESULTS: The oil showed chemical markers, including α-pinene (87.85%), trans-caryophyllene (1.57%), limonene (1.49%) and ß -pinene (1.42%), and activity against all strains: Staphylococcus aureus (MIC = MBC = 0.22 mg/mL), Staphylococcus epidermidis (MIC = 0.11 mg/mL and MBC = 0.22 mg/mL), Escherichia coli (MIC = 0.88 mg/mL and MBC = 1.75 mg/mL), Pseudomonas aeruginosa (MIC = MBC = 7 mg/mL) and Salmonella Enteritidis (MIC = MBC = 0.44 mg/mL). In vitro cytotoxicity tests showed that the oil is not toxic and has slight antitumor activity. CONCLUSIONS: We conclude that the M. urundeuva oil results are promising, with prospects of being pharmacologically viable.

Bactericidal Activity and Synergy Studies of Peptide AP-CECT7121 Against Multi-resistant Bacteria Isolated from Human and Animal Soft Tissue Infections.

AP-CECT7121 is an antimicrobial peptide, produced by Enterococcus faecalis CECT7121, with bactericidal activity against Gram-positive bacteria. The aim of this study was to evaluate the bactericidal activity of AP-CECT7121, alone and with gentamicin, against multi-resistant bacteria isolated from human and animals with soft tissue infections. During the period 2014-2015, bacterial strains producing human and animal soft tissue infections were studied. Samples from patients attended at a general hospital and cattle from four dairies in the Province of Buenos Aires (Argentina) were included. Twenty-two methicillin-resistant Staphylococcus aureus (11, human blood samples; 11, cow milk) and five vancomycin-resistant Ent. faecium strains isolated from four mastitic dairy cows were tested. AP-CECT7121 (12 mg/L) potency was assessed by time-kill curves alone or with sub-inhibitory concentrations of gentamicin. All staphylococcal strains were susceptible to gentamicin; enterococci did not show high-level gentamicin resistance. Colony counts were carried out at 0, 2, 4, 8, and 24 h of incubation. AP-CECT7121 showed bactericidal activity against all the enterococcal strains. In addition, AP-CECT7121 had a bactericidal effect on most staphylococci (16/22). Early AP-CECT7121/gentamicin synergy (4-8 h) for all staphylococci was detected. At 24 h, synergy (19/22) and indifference (3/22) were observed. Synergy with gentamicin was detected for staphylococci. AP-CECT7121 constitutes an attractive candidate for its use as a natural therapeutic tool for the treatment of infections produced by multi-resistant Staph. aureus and vancomycin-resistant Ent. faecium isolated from humans and animals.