Additive Antimicrobial Effect Research Articles

Enhanced Antimicrobial Activity of Laser‐induced Graphene Wrapped Tri‐Metal Organic Framework Nanocomposites

Crystalline and porous metal‐organic frameworks (MOFs) are potential candidates for different antibacterial, photocatalytic, and adsorption applications. Moreover, multi‐principal element nanoparticles are effective against multidrug‐resistant bacteria, and combining metals with carbon nanomaterials can enhance activity. In this study, a Tri‐MOF comprised of iron, zinc, and cobalt and 2‐methyl imidazole was grown together with laser‐induced graphene (LIG) powder. Electron microscopy imaging showed the successful preparation and the crystalline nature of the LIG/Tri‐MOF composite. Fourier‐transform infrared and X‐ray photoelectron spectroscopy confirmed a non‐covalent mixture of LIG and Tri‐MOF. Compared with the negligible activity of LIG alone, low doses (0.91‐4.54 mg/mL) of the prepared LIG/Tri‐MOF composite showed excellent antibacterial activity (≥ 95% bacterial removal) and a MIC of 0.6 mg/mL, for Gram‐negative bacteria via the gradual leaching of metal ions and organic linker from the material enhanced by bacterial aggregation near the LIG/Tri‐MOF. Compared to a mixture of separately synthesized Tri‐MOF and LIG, the LIG/Tri‐MOF composite showed improved antibacterial effects. All materials showed cytotoxicity for L929 mouse cell lines, the solids showing a disrupting effect on cells grown in vitro. Performance‐enhancing combinations of various materials leading to synergistic or additive antimicrobial effects is an essential strategy for minimizing the possible emergence of antibiotic‐resistant strains.This article is protected by copyright. All rights reserved.

Azalomycin F4a targets peptidoglycan synthesis of Gram-positive bacteria revealed by high-throughput CRISPRi-seq analysis

Azalomycin F4a is a promising 36-membered polyhydroxy macrolide that shows antibacterial activity against drug-resistant Gram-positive bacteria, but its exact working mechanism remains to be elusive. Here, we isolated the azalomycin F4a product from a Streptomyces solisilvae and demonstrated its antibacterial activity against Gram-positive pathogens including Streptococcus pneumoniae, Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA). We further showed that combination of azalomycin F4a with methicillin has an additive antimicrobial effect on MRSA, where the minimal inhibitory concentrations (MIC) of methicillin to MRSA was decreased by 1000-fold in the presence of sublethal concentration of azalomycin F4a. A CRISPRi-seq based whole genome screen was employed to identify the potential targets of azalomycin F4a, which revealed that peptidoglycan synthesis (PGS) was inhibited by azalomycin F4a. Furthermore, azalomycin F4a treatment could significantly impair S. aureus biofilm formation. Our research highlights that cell wall synthesis is an additional target for novel classes of macrolide besides ribosome.

Short-term Clinical and Microbiological Performance of Resin-modified Glass Ionomer Cement Containing Chlorhexidine for Atraumatic Restorative Treatment.

This study evaluated the short-term clinical and microbiological performance of resin-modified glass ionomer cement (RM-GIC) cement containing chlorhexidine (CHX) for atraumatic restorative treatment (ART) in primary teeth. The clinical trial was conducted in 36 children that received ART in primary molars either with GIC (group I, n = 18) or GIC containing 1.25% CHX (group II, n = 18). The survival rate of restorations was checked 7 days, 3, and 6 months after their application when saliva and biofilm were collected for microbiological assessment of mutans streptococci (MS) counts. Data were analyzed using the Kruskal-Wallis/Mann-Whitney U tests for clinical analysis and microbiological evaluations (p < 0.05). The survival rate of restorations was similar comparing groups I with II. Microbiological analysis showed a significant reduction in MS levels 7 days after the treatment in both saliva and biofilm of children treated with RM-GIC containing CHX (group II); however, MS counts at 3 and 6 months did not differ from the initial counts. A total of 1.25% CHX improved the microbiological properties of GIC in the short term without impairing the clinical performance of ART restorations. Glass ionomer cement (GIC) containing CHX could be an alternative in ART procedures with the objective of promoting an additional antimicrobial effect, which is interesting for children with high counts of MS during the initial phase of adaptation to dental treatment. da Silva ME, de Sena MD, Colombo NH, et al. Short-term Clinical and Microbiological Performance of Resin-modified Glass Ionomer Cement Containing Chlorhexidine for Atraumatic Restorative Treatment. Int J Clin Pediatr Dent 2023;16(S-1):S27-S32.

Comparative study of zinc oxide nanocomposites with different noble metals synthesized by biological method for photocatalytic disinfection of Escherichia coli present in hospital wastewater.

Binary zinc oxide (ZnO) nanocomposites with different noble metals, silver (Ag) and ruthenium (Ru), were prepared from an aqueous leaf extract of Callistemon viminalis. The biosynthesized photocatalysts were characterized and examined for their photocatalytic disinfection against Escherichia coli isolated from hospital wastewater. The influence of the different noble metals showed a difference in physicochemical characteristics and photocatalytic efficiency between Ag-ZnO and Ru-ZnO. The photocatalytic degradation of methylene blue and photocatalytic disinfection were found to be in the order Ag-ZnO > Ru-ZnO > ZnO. The photocatalytic disinfection of Ag-ZnO reached a 75% reduction in 60 min, compared to 34 and 9% reductions of Ru-ZnO and ZnO, respectively. The kinetic reaction rate for the photocatalytic disinfection of Ag-ZnO was found to be 2.8 times higher than that of Ru-ZnO. The outstanding photocatalytic activity of Ag-ZnO over Ru-ZnO was attributed to higher crystallinity, greater UVA adsorption capacity, smaller particle size, and the additional antimicrobial effect of Ag itself. The C. viminalis-mediated Ag-ZnO nanocomposites can be a potential candidate for photocatalytic disinfection of drug-resistant E. coli in hospital wastewater.

Isobolographic analysis of the ciprofloxacin-gentamicin combination against beta-lactamase-producing Staphylococcus aureus.

Bacterial multi-resistance is a serious global problem that continues to worsen over time due to multiple factors. Among these factors, it is important to highlight the clinical misuse of antibiotics and the mechanisms that microorganisms have developed to protect themselves from these drugs. In this sense, Staphylococcus aureus (S. aureus) is a pathogen that has found a way to resist many of the drugs currently in use, so infections by this bacterium represent a serious clinical problem. The purpose of this study was to determine the type of interaction between ciprofloxacin and gentamicin against beta-lactamase-producing S. aureus using isobolographic analysis. Ciprofloxacin (0.5-0.05 mg/mL) and gentamicin (10-1 mg/mL) were used to make concentration-dependent curves for each individual drug. Thereafter, the 50 inhibitory concentration (IC50 ) of each drug was obtained, and different proportions of the ciprofloxacin-gentamicin combination-0.5:0.5, 0.8:0.2, 0.2:0.8, 0.9:0.1, 0.1:0.9, 0.95:0.05, and 0.05:0.95-were evaluated. The isobolographic analysis and the interaction index were used to analyze the data. The isobolographic evaluation of the combination showed that the ratios 0.5:0.5, 0.8:0.2, 0.2:0.8, and 0.9:0.1 produced a synergistic anti-staphylococcal effect, and the 0.95:0.05 ratio induced an additive antibacterial effect. Finally, the 0.1:0.9 and 0.05:0.95 ratios of the combination presented antagonistic effects against S. aureus. On the other hand, the interaction index showed similar results to the isobolographic analysis. The isobolographic results of this in vitro assay show that the ciprofloxacin-gentamicin combination induces synergistic, additive, and antagonistic antimicrobial effects against S. aureus.

Synergetic Antimicrobial Effect of Silver Nanoparticles Conjugated with Iprodione against Valsa mali.

Apple tree canker induced by Valsa mali is a vital disease in apple production around the world, and it highlyimpacts the development of apple industry. It is of great significance to study the inhibition effect of common fungicides and develop new fungistats for comprehensive control of apple tree canker. In this experiment, the inhibition activity of five fungicides, including mancozeb, metalaxyl, iprodione, prochloraz, and difenoconazole along with biosynthesized nanosilver against V. mali, were measured with the mycelium growth rate and agar well diffusion methods. The results showed that iprodione exhibited the best inhibitory effect, the median inhibition concentration (IC50) of iprodione and nanosilver was 0.62 μg.mL−1 and 45.50 μg.mL−1, the suppression rate achieved 67.93% at 200 μg.mL−1 of nanosilver. Moreover, a remarkable additive and synergistic antimicrobial effect was verified when silver nanoparticles were conjugated with iprodione at 9:1, 8:2, 7:3, and 6:4 (v/v), and the toxicity ratio was 1.04, 1.13, 1.01, and 0.98, respectively. It is proven that biosynthesized silver nanoparticles could effectively inhibit Valsa mali, and it is possible to develop and screen silver nanoparticle-based nano pesticides to manage plant diseases synthetically.

Tranexamic Acid in Combination With Vancomycin or Gentamicin Has a Synergistic Effect Against Staphylococci.

BackgroundTranexamic acid (TXA) is an antifibrinolytic agent applied in orthopedic surgery and has been proven to reduce post-surgery infection rates. We previously showed that TXA also had an additional direct antimicrobial effect against planktonic bacteria. Therefore, we aimed to evaluate whether it has a synergistic effect if in combination with antibiotics.Materials and MethodsThree ATCC and seven clinical strains of staphylococci were tested against serial dilutions of vancomycin and gentamicin alone and in combination with TXA at 10 and 50 mg/ml. The standardized microtiter plate method was used. Minimal inhibitory concentrations (MICs) were calculated by standard visualization of well turbidity (the lowest concentration at which complete absence of well bacterial growth was observed by the researcher) and using the automated method (the lowest concentration at which ≥80% reduction in well bacterial growth was measured using a spectrophotometer).ResultsTranexamic acid-10 mg/ml reduced the MIC of vancomycin and gentamicin with both the standard method (V: 1-fold dilution, G: 4-fold dilutions) and the automated turbidity method (vancomycin: 8-fold dilutions, gentamicin: 8-fold dilutions). TXA-50 mg/ml reduced the MIC of gentamicin with both the standard turbidity method (6-fold dilutions) and the automated turbidity method (1-fold dilutions). In contrast, for vancomycin, the MIC remained the same using the standard method, and only a 1-fold dilution was reduced using the automated method.ConclusionOurs was a proof-of-concept study in which we suggest that TXA may have a synergistic effect when combined with both vancomycin and gentamicin, especially at 10 mg/ml, which is the concentration generally used in clinical practice.

Antimicrobial activity of combined essential oils of Origanum vulgare L. and Houttuynia cordata T. against Salmonella enteritidis and Salmonella Paratyphi β

Based on the determination of the chemical composition of essential oils by GC–MS, the antibacterial activities and mechanism of combined essential oils extracted from Origanum vulgare L. and Houttuynia cordata T. (denoted as C-EO hereafter) were investigated. The possibility of using C-EO as a potential substitute for synthetic antiseptics was studied for the first time. C-EO exhibited significant antibacterial and anti-biofilm activities against Salmonella Enteritidis and Salmonella Paratyphi β. The FICI of C-EO against S. Enteritidis and S. Paratyphi β were all within 0.563, it indicates that C-EO demonstrated additive antibacterial effects. Antibacterial mechanism of C-EO against the two strains was determined by analyzing the completeness of the cell membrane and the counteractant for bacterial biofilm. The finding that C-EO plays a bacteriostatic effect by disrupting cell walls and membranes was verified intuitively via scanning electron microscopy. Results showed that C-EO may potentially play an essential role in food preservation. Novelty impact statement The antibacterial mechanism of the combined EOs (C-EO, which were extracted from Origanum vulgare L. and Houttuynia cordataT) against Salmonella enteritidis and Salmonella paratyphi β was determined for the first time. The C-EO exerted additive antimicrobial effect against S. enteritidis and S. paratyphi β. This C-EO is apparently a potential candidate for future food preservatives.

Combined effects of intermittent radio frequency heating with cinnamon oil vapor on microbial control and quality changes of alfalfa seeds

Alfalfa sprouts have high nutritional values when consumed raw, but are easily contaminated by food pathogens. This study aimed to evaluate effects of essential oil (EO) vapors, RF heating and their combinations on microbial inactivation, germination rate and generated sprouts' quality of alfalfa seeds at moisture contents of 7.52%, 9.53% and 11.45% wet basis (w.b.). Results showed that cinnamon oil and oregano oil vapors both had antimicrobial effects against Salmonella on alfalfa seeds and cinnamon oil vapor had a little better activity. Weibull model well fitted the Salmonella inactivation curves under RF heating. The rate of Salmonella inactivation increased but germination rate decreased with increasing temperature and moisture content of seeds. The intermittent RF treatments improved the heating uniformity and germination rate of the whole batch of seeds as compared to the continuous RF heating. The combination of intermittent RF heating and cinnamon oil vapor exhibited additive antimicrobial effects, up to 3.99–4.12 log CFU/g Salmonella reductions, and maintained the germination rate above 90%. However, for natural microbial decontamination, combined treatments only caused 0.56–0.82 log CFU/g reductions of total bacterial counts. The fresh weight, length, flavor, the content of phenolics and ascorbic acid, and antioxidant capacity of generated sprouts were not significantly impacted. The study provided an effective method for microbial control on sprouting seeds.

Photodynamic Therapy Combined with Antibiotics or Antifungals against Microorganisms That Cause Skin and Soft Tissue Infections: A Planktonic and Biofilm Approach to Overcome Resistances.

The present review covers combination approaches of antimicrobial photodynamic therapy (aPDT) plus antibiotics or antifungals to attack bacteria and fungi in vitro (both planktonic and biofilm forms) focused on those microorganisms that cause infections in skin and soft tissues. The combination can prevent failure in the fight against these microorganisms: antimicrobial drugs can increase the susceptibility of microorganisms to aPDT and prevent the possibility of regrowth of those that were not inactivated during the irradiation; meanwhile, aPDT is effective regardless of the resistance pattern of the strain and their use does not contribute to the selection of antimicrobial resistance. Additive or synergistic antimicrobial effects in vitro are evaluated and the best combinations are presented. The use of combined treatment of aPDT with antimicrobials could help overcome the difficulty of fighting high level of resistance microorganisms and, as it is a multi-target approach, it could make the selection of resistant microorganisms more difficult.

Synthesis and characterization of a nano-formulation for long lasting sterilization effect

The current COVID-19 pandemic has increased the use of alcohol based hand sanitisers globally. These available alcohol based sanitisers cannot provide an antibacterial effect for an extended period of time, after the evaporation of ethanol. Hence, the need for a sanitiser with an anti-microbial activity combined with a long lasting effect is the need of the hour. In this study, we report the synthesis of a long lasting sanitiser from ozonated omega 9 fatty acid esters in an ethanolic medium. The formed vesicles made of the fatty acids have been characterized by DLS, Zeta potential, and time resolved fluorescence anisotropy studies. Ethanol although, provides an antibacterial effect, the effect is more pronounced in our prepared formulation owing to its high peroxide value that generates additional oxidative stress. Finally, this additional antimicrobial effect will have relevance in the current COVID-19 scenario in providing a long lasting hand sanitiser.

Кератит, индуцированный применением мягкой контактной линзы

A clinical case demonstrates that improper use of soft contact lenses can induce serious changes in the cornea, followed by long-term treatment, which in turn may be ineffective due to the developed antibiotic resistance. In similar cases, the use of UV crosslinking provides an additional antimicrobial effect, which ultimately allows the inflammatory process to be resolved. Key words: keratitis, soft contact lens, crosslinking.

Evaluation of antimicrobial and antioxidant efficacy of hydro ethanol extract of peels of Kufri Chandramukhi, Kufri Chipsona‐3, and Kufri Jyoti potato varieties alone and in combination

AbstractThe potato processing industries generate substantial quantities of phenolic‐rich potato peels as waste by‐products that could be valuable natural sources of antimicrobials and antioxidants in food industry. The present study is aimed to evaluate antimicrobial and antioxidant potential of hydro ethanol extract of peels of three commonly used potato varieties (Kufri Chandramukhi, Kufri Chipsona‐3, and Kufri Jyoti) alone and in combination along with cytotoxicity evaluation. At their individual effect, antimicrobial and antioxidant potential of potato peel extracts were found to be in the following decreasing order: Kufri Chisona‐3 &gt; Kufri Jyoti &gt; Kufri Chandramukhi. In combination, peel extracts of Kufri Chipsona‐3/Kufri Jyoti blend demonstrated synergistic antimicrobial and antioxidant interactions whereas other tested combinations showed additive antimicrobial and antioxidant effects. The peel extracts of Kufri Chipsona‐3/Kufri Jyoti blend did not show any cytotoxic effect up to 1000 μg/ml concentration. Besides, a high positive correlation between total phenolic contents and antimicrobial activity of potato peel extracts was observed. The results provide evidence that hydro ethanol extract of potato peels of Kufri Chipsona‐3/Kufri Jyoti blend may help in designing a more potent safe and effective novel natural antimicrobial and antioxidant agents in food and pharmaceutical industries.

Antioxidative, Antifungal and Additive Activity of the Antimicrobial Peptides Leg1 and Leg2 from Chickpea.

The fight against food waste benefits from novel agents inhibiting spoilage. The present study investigated the preservative potential of the antimicrobial peptides Leg1 (RIKTVTSFDLPALRFLKL) and Leg2 (RIKTVTSFDLPALRWLKL) recently identified in chickpea legumin hydrolysates. Checkerboard assays revealed strong additive antimicrobial effects of Leg1/Leg2 with sodium benzoate against Escherichia coli and Bacillus subtilis with fractional inhibitory concentrations of 0.625 and 0.75. Additionally, Leg1/Leg2 displayed antifungal activity with minimum inhibitory concentrations of 500/250 µM against Saccharomyces cerevisiae and 250/125 µM against Zygosaccharomyces bailii. In contrast, no cytotoxic effects were observed against human Caco-2 cells at concentrations below 2000 µM (Leg1) and 1000 µM (Leg2). Particularly Leg2 showed antioxidative activity by radical scavenging and reducing mechanisms (maximally 91.5/86.3% compared to 91.2/94.7% for the control ascorbic acid). The present results demonstrate that Leg1/Leg2 have the potential to be applied as preservatives protecting food and other products against bacterial, fungal and oxidative spoilage.

A Study on Different Hurdle Factors of Nano Metal Vitamin Complex for the Prevention of Microbial Spoilage in Seafood

Hurdles that have a positive effect by inhibiting microorganisms may have a negative one on other parameters such as nutritional properties or sensory quality, depending on their intensity. In order to lower the preservative level, the hurdle technology concept has been developed, consisting in using combined hurdles to establish an additive antimicrobial effect, and even sometimes a synergetic one, thus improving the safety and the sensory quality of food. The antibacterial and anti-oxidant potential of copper oxide nano particles coupled with vitamin-E (CuONPs+VE) was investigated by applying the novel hurdle factors against seafood pathogens and by studying the cell viability using MTT assays. The hurdle method is proposed to explain the significance of combined use of different preservation factors as synergistic effects instead of using a large-intensity preservation factor. Effect of CuONPs+VE and chilling temperatures (-18°C and +4°C); and Effect of CuONPs+VE and brine salts at various concentrations (5%, 10%,) were evaluated. CuONPs+VE with different chilling temperatures and brine salt concentration showed significant results on compared to control temperatures. Thus CuONPs+VE due to their bacteriostatic activity can be efficiently used in hurdle technology which reduces the food spoiling organisms. Thus CuONPs+VE in combined with hurdle technology can be used as alternatives for chemical preservatives in preservation techniques.

Silver nanoparticles doped with silver cations and stabilized with maleic acid copolymers: specific structure and antimicrobial properties

The specificity of the structure of polymer complexes of silver nanoparticles and silver cations is revealed, and the additive antimicrobial effect of the system components is shown.

Honey Combination Therapies for Skin and Wound Infections: A Systematic Review of the Literature.

Topical application of medical grade honey is recommended for the clinical management of wound infections. The suitability of honey as a wound healing agent is largely due to its antibacterial activity, immune modulatory properties, and biocompatibility. Despite the usefulness of honey in wound healing, chronic wound infections continue to be a global problem requiring new and improved therapeutic interventions. Several recent studies have investigated the effects of combining honey with other therapies or agents with the aim of finding more efficacious treatments. In this systematic review, the database PubMed was used to carry out a search of the scientific literature on the combined effects of honey and other therapies on antimicrobial activity and wound and skin healing. The search revealed that synergistic or additive antimicrobial effects were observed in vitro when honey was combined with antibiotics, bacteriophages, antimicrobial peptides, natural agents, eg, ginger or propolis and other treatment approaches such as the use of chitosan hydrogel. Outcomes depended on the type of honey, the combining agent or treatment and the microbial species or strain. Improved wound healing was also observed in vivo in mice when honey was combined with laser therapy or bacteriophage therapy. More clinical studies in humans are required to fully understand the effectiveness of honey combination therapies for the treatment of skin and wound infections.

Steroid Derivatives as Potential Antimicrobial Agents Against Staphylococcus aureus Planktonic Cells.

In this work, the antibacterial activity of deflazacort and several of its synthetic precursors was tested against a panel of bacterial pathogens responsible for most drug-resistant infections including Staphylococcus aureus, Enterococcus spp., Acinetobacter baumannii, Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, and Enterobacter spp. The derivative of deflazacort, PYED-1 (pregnadiene-11-hydroxy-16α,17α-epoxy-3,20-dione-1) showed the best antibacterial activity in a dose-dependent way. We focused on the action of PYED-1 against S. aureus cells. PYED-1 exhibited an additive antimicrobial effect with gentamicin and oxacillin against the methicillin-resistant S. aureus isolate 00717. In addition to its antimicrobial effect, PYED-1 was found to repress the expression of several virulence factors of S. aureus, including toxins encoded by the hla (alpha-haemolysin), hlb (beta-haemolysin), lukE-D (leucotoxins E-D), and sea (staphylococcal enterotoxin A) genes, and cell surface factors (fnbB (fibronectin-binding protein B) and capC (capsule biosynthesis protein C)). The expression levels of autolysin isaA (immunodominant staphylococcal antigen) were also increased.

Photodynamic inactivation of antibiotic‐resistant Gram‐positive bacteria: Challenges and opportunities

AbstractThe growing numbers of pathogenic bacteria acquiring multidrug resistance are posing the challenges to develop novel therapeutic approaches. Photodynamic bacterial inactivation assaults multiple subcellular targets of pathogenic bacteria, including Staphylococcus aureus, with low tendency to induce further resistance. A wide range of aPDI photosensitizers were investigated for localized infections, including endogenous porphyrins and encapsulated sensitizers in nanoparticles. This mini review presents the concepts of aPDI, a field consisting of more than 3000 research articles published over 30 years. Mutated PBP membrane enzymes of multiantibiotic resistant S. aureus are plausible targets of aPDI. Synergistic aPDI using simultaneously DP, light irradiation and the antibiotic oxacillin, was recently described, eliminating temporarily oxacillin resistance. Additive antimicrobial effects were achieved with DP‐aPDI combined with additional classes of antibiotics. We propose that mutual aPDI adjuvant with antibiotics or other toxic molecules is opening a new therapeutic window for topical life‐threatening infections, without induction of further resistance.

Antimicrobial activity of Citrus spp. and Anethum graveolens components against Candida metapsilosis in ranch sauce.

In this paper, a study was carried out to test the inhibitory effect of a natural food compound (NFC), based on flavonoids (naringenin, hesperetin, tangeritin, luteolin, apigenin and kaempferol) from citrus and dill, in ranch sauce. A strain of C. metapsilosis, isolated from a spoiled sample of ranch sauce, was used as target pathogen microorganism. The inhibitory effect of NFC was compared with a common mixture of chemical preservatives used in this type of sauces: potassium sorbate and sodium benzoate (S/B). An in vitro test was performed by the microtiter plate assay at 10, 25 and 37°C for 24h in modified Tryptic Soy Broth. An additive antimicrobial effect had been observed in the combination of acetic acid and NFC. The results of the microtiter assay were validated in a challenge test in ranch sauce at 5, 25 and 37°C for 10weeks. NFC showed partial fungicidal effect against C. metapsilosis, reducing two logarithmic units at 5°C for 10weeks. At 5°C, the traditional doses of S/B used in ranch sauce decreased viable cells to non-detectable counts from the second week of the experiment. At 25 and 37°C, the use of S/B mixture or the use of NFC showed the same fungicidal effect. The incorporation of NFC, alone or in combination with acetic acid, opens the possibility of formulating clean label sauces with good protection against the development of the acid resistant yeast C. metapsilosis.