Enhancement of Antibiofilm Activity of Ciprofloxacin against Staphylococcus aureus by Administration of Antimicrobial Peptides.
TL;DR: In this paper, the ability of the antimicrobials to disrupt biofilms was determined using crystal violet and live/dead staining, and effects on the cell membranes of biofilm cells were evaluated by measuring release of dyes and ATP and nucleic acids.
Abstract: Staphylococcus aureus can develop resistance by mutation, transfection or biofilm formation. Resistance was induced in S. aureus by growth in sub-inhibitory concentrations of ciprofloxacin for 30 days. The ability of the antimicrobials to disrupt biofilms was determined using crystal violet and live/dead staining. Effects on the cell membranes of biofilm cells were evaluated by measuring release of dyes and ATP, and nucleic acids. None of the strains developed resistance to AMPs while only S. aureus ATCC 25923 developed resistance (128 times) to ciprofloxacin after 30 passages. Only peptides reduced biofilms of ciprofloxacin-resistant cells. The antibiofilm effect of melimine with ciprofloxacin was more (27%) than with melimine alone at 1X MIC (p < 0.001). Similarly, at 1X MIC the combination of Mel4 and ciprofloxacin produced more (48%) biofilm disruption than Mel4 alone (p < 0.001). Combinations of either of the peptides with ciprofloxacin at 2X MIC released ≥ 66 nM ATP, more than either peptide alone (p ≤ 0.005). At 2X MIC, only melimine in combination with ciprofloxacin released DNA/RNA which was three times more than that released by melimine alone (p = 0.043). These results suggest the potential use of melimine and Mel4 with conventional antibiotics for the treatment of S. aureus biofilms.
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TL;DR: The MUVi-UVC was able to kill 99.999% of all of the tested bacteria, fungi, coronavirus and bacteria in the biofilms if used for 5 min using all three lights in the setup with the glass slides in a vertical position, therefore, this UVC device is an effective technology to disinfect medical devices.
Abstract: Ultra-violet (UV) C (200–280 wavelength) light has long been known for its antimicrobial and disinfecting efficacy. It damages DNA by causing the dimerization of pyrimidines. A newly designed technology (MUVi-UVC; Mobile UV Innovations Pty Ltd., Melbourne, VIC, Australia) that emits UVC at 240 nm is composed of an enclosed booth with three UVC light stands each with four bulbs, and has been developed for disinfecting mobile medical equipment. The aim of this project was to examine the spectrum of antimicrobial activity of this device. The experiments were designed following ASTM E1052-20, EN14561, BSEN14476-2005, BSEN14562-2006 and AOAC-Official-Method-966.04 standards for surface disinfection after drying microbes on surfaces. The disinfection was analyzed using Staphylococcus aureus (ATCC 6538), Pseudomonas aeruginosa (6294), Candida auris (CBS 12373), spores of Aspergillus niger (ATCC 16404), coronavirus (SARS-CoV-2 surrogate ATCC VR-261) as well as a methicillin-resistant Staphylococcus aureus (SA31), a carbapenem- and polymyxin-resistant Pseudomonas aeruginosa (PA219), Escherichia coli K12 (ATCC 10798) and Salmonella typhi (ATCC 700730). The parameters of time, the number of lights and direction of the sample facing the lights were examined. The MUVi-UVC was able to kill 99.999% of all of the tested bacteria, fungi, coronavirus and bacteria in the biofilms if used for 5 min using all three lights in the setup with the glass slides in a vertical position. However, for fungal spores, 30 min were required to achieve 99.999% killing. There was a small but insignificant effect of having the surface horizontally or vertically aligned to the UV lights. Therefore, this UVC device is an effective technology to disinfect medical devices.
8 citations
TL;DR: This study provides a simple and effective antibacterial coating strategy that can be applied to biomaterials to reduce biofilm-mediated infections and assesses the biocompatibility of these coated materials.
Abstract: The prevention and treatment of biofilm-mediated infections remains an unmet clinical need for medical devices. With the increasing prevalence of antibiotic-resistant infections, it is important that novel approaches are developed to prevent biofilms forming on implantable medical devices. This study presents a versatile and simple polydopamine surface coating technique for medical devices, using a new class of antibiotics—antimicrobial peptidomimetics. Their unique mechanism of action primes them for activity against antibiotic-resistant bacteria and makes them suitable for covalent attachment to medical devices. This study assesses the anti-biofilm activity of peptidomimetics, characterises the surface chemistry of peptidomimetic coatings, quantifies the antibacterial activity of coated surfaces and assesses the biocompatibility of these coated materials. X-ray photoelectron spectroscopy and water contact angle measurements were used to confirm the chemical modification of coated surfaces. The antibacterial activity of surfaces was quantified for S. aureus, E. coli and P. aeruginosa, with all peptidomimetic coatings showing the complete eradication of S. aureus on surfaces and variable activity for Gram-negative bacteria. Scanning electron microscopy confirmed the membrane disruption mechanism of peptidomimetic coatings against E. coli. Furthermore, peptidomimetic surfaces did not lyse red blood cells, which suggests these surfaces may be biocompatible with biological fluids such as blood. Overall, this study provides a simple and effective antibacterial coating strategy that can be applied to biomaterials to reduce biofilm-mediated infections.
4 citations
TL;DR: A new endophytic fungal isolate has been identified for the first time as Rhizopus oryzae AUMC14899 from Opuntia ficus-indica (L.) and submitted to GenBank under the accession number MZ025968 as discussed by the authors .
Abstract: A significant threat to the public's health is the rise in antimicrobial resistance among numerous nosocomial bacterial infections. This may be a detriment to present initiatives to enhance the health of immune-compromised patients. Consequently, attention has been devoted to exploring new bioactive compounds in the field of drug discovery from endophytes. Therefore, this study is the first on the production of L-tyrosine (LT) as a promising bio-therapeutic agent from endophytic fungi.A new endophytic fungal isolate has been identified for the first time as Rhizopus oryzae AUMC14899 from Opuntia ficus-indica (L.) and submitted to GenBank under the accession number MZ025968. Separation of amino acids in the crude extract of this fungal isolate was carried out, giving a higher content of LT, which is then characterized and purified. LT exhibited strong antibacterial and anti-biofilm activities against multidrug-resistant Gram-negative and Gram-positive bacteria. The recorded minimum inhibitory concentration (MIC) values ranged from 6 to 20 µg/ml. In addition, LT caused a strong reduction in biofilm formation and disrupted the preformed biofilm. Moreover, results indicated that LT supported cell viability, evidencing hemocompatibility and no cytotoxicity.Our findings suggest that LT has potential as a therapeutic agent due to its potential antibacterial, anti-biofilm, hemocompatibility, and lack of cytotoxic activities, which may also increase the range of therapy options for skin burn infections, leading to the development of a novel fungal-based drug.
3 citations
TL;DR: The green synthesis of AuNFs from the rosemary and immortelle extracts can be applied as a potential agent to overcome the growth of biofilm-producing microorganisms in food industries.
Abstract: This study was concerned with the green synthesis of gold nanoflowers (AuNFs) using the bioactive constituents of Rosmarinus officinalis (rosemary) and Helichrysum italicum (immortelle) extracts, as reducer and stabilizer agents along with the determination of their antibacterial and antibiofilm activity against E. coli, S. aureus, and S. epidermidis. The AuNFs were characterized using STEM, UV–Vis, DLS, ZETA, FESEM-EDX, and FTIR techniques. The antibacterial and antibiofilm activity of the AuNFs were evaluated by microdilution broth and microtiter plate (MTP) tests, respectively. STEM and DLS analysis confirmed the flower-like morphology of gold nanoparticle clusters of R. officinalis-AuNFs (R-AuNFs) and H. italicum-AuNFs (H-AuNFs) with a size of 20–130 nm and 15–90 nm, respectively. The MICs of R-AuNFs were found to be 40 µg/mL for E. coli and S. epidermidis and 160 µg/mL for S. aureus. The MICs of H-AuNFs against all bacterial strains were 20 µg/mL. All tested AuNFs exhibited a strong dose-dependent antibiofilm activity against the test strains, and H-AuNFs was more effective than R-AuNFs. The green synthesis of AuNFs from the rosemary and immortelle extracts can be applied as a potential agent to overcome the growth of biofilm-producing microorganisms in food industries.
2 citations
TL;DR: Melimine, a chimeric cationic peptide that has been tested in Phase I and II human clinical trials, was immobilized onto the surface of 3D-printed medical-grade polycaprolactone (mPCL) scaffolds via covalent binding and adsorption, which resulted in the inhibition of biofilm formation in vitro.
Abstract: Biomaterial-associated infections are one of the major causes of implant failure. These infections result from persistent bacteria that have adhered to the biomaterial surface before, during, or after surgery and have formed a biofilm on the implant’s surface. It is estimated that 4 to 10% of implant surfaces are contaminated with bacteria; however, the infection rate can be as high as 30% in intensive care units in developed countries and as high as 45% in developing countries. To date, there is no clinical solution to prevent implant infection without relying on the use of high doses of antibiotics supplied systemically and/or removal of the infected device. In this study, melimine, a chimeric cationic peptide that has been tested in Phase I and II human clinical trials, was immobilized onto the surface of 3D-printed medical-grade polycaprolactone (mPCL) scaffolds via covalent binding and adsorption. X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) spectra of melimine-treated surfaces confirmed immobilization of the peptide, as well as its homogeneous distribution throughout the scaffold surface. Amino acid analysis showed that melimine covalent and noncovalent immobilization resulted in a peptide density of ∼156 and ∼533 ng/cm2, respectively. Furthermore, we demonstrated that the immobilization of melimine on mPCL scaffolds by 1-ethyl-3-[3-(dimethylamino)propyl] carbodiimide hydrochloride (EDC) coupling and noncovalent interactions resulted in a reduction of Staphylococcus aureus colonization by 78.7% and 76.0%, respectively, in comparison with the nonmodified control specimens. Particularly, the modified surfaces maintained their antibacterial properties for 3 days, which resulted in the inhibition of biofilm formation in vitro. This system offers a biomaterial strategy to effectively prevent biofilm-related infections on implant surfaces without relying on the use of prophylactic antibiotic treatment.
1 citations
References
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TL;DR: The aim of broth and agar dilution methods is to determine the lowest concentration of the assayed antimicrobial agent (minimal inhibitory concentration, MIC) that, under defined test conditions, inhibits the visible growth of the bacterium being investigated.
Abstract: The aim of broth and agar dilution methods is to determine the lowest concentration of the assayed antimicrobial agent (minimal inhibitory concentration, MIC) that, under defined test conditions, inhibits the visible growth of the bacterium being investigated. MIC values are used to determine susceptibilities of bacteria to drugs and also to evaluate the activity of new antimicrobial agents. Agar dilution involves the incorporation of different concentrations of the antimicrobial substance into a nutrient agar medium followed by the application of a standardized number of cells to the surface of the agar plate. For broth dilution, often determined in 96-well microtiter plate format, bacteria are inoculated into a liquid growth medium in the presence of different concentrations of an antimicrobial agent. Growth is assessed after incubation for a defined period of time (16-20 h) and the MIC value is read. This protocol applies only to aerobic bacteria and can be completed in 3 d.
4,223 citations
TL;DR: Owing to the heterogeneous nature of the biofilm, it is likely that there are multiple resistance mechanisms at work within a single community.
3,578 citations
TL;DR: Although many studies support that bacterial membrane damage is a lethal event for bacteria, other studies point to a multihit mechanism in which the peptide binds to several targets in the cytoplasmic region of the bacteria.
Abstract: Water-membrane soluble protein and peptide toxins are used in the defense and offense systems of all organisms, including plants and humans. A major group includes antimicrobial peptides, which serve as a nonspecific defense system that complements the highly specific cell-mediated immune response. The increasing resistance of bacteria to conventional antibiotics stimulated the isolation and characterization of many antimicrobial peptides for potential use as new target antibiotics. The finding of thousands of antimicrobial peptides with variable lengths and sequences, all of which are active at similar concentrations, suggests a general mechanism for killing bacteria rather than a specific mechanism that requires preferred active structures. Such a mechanism is in agreement with the “carpet model” that does not require any specific structure or sequence. It seems that when there is an appropriate balance between hydrophobicity and a net positive charge the peptides are active on bacteria. However, selective activity depends also on other parameters, such as the volume of the molecule, its structure, and its oligomeric state in solution and membranes. Further, although many studies support that bacterial membrane damage is a lethal event for bacteria, other studies point to a multihit mechanism in which the peptide binds to several targets in the cytoplasmic region of the bacteria.
1,442 citations
TL;DR: The ecology of antibiotics and the ability of subinhibitory concentrations to select for bacterial resistance are discussed and the effects of low-level drug exposure on bacterial physiology are considered, including the generation of genetic and phenotypic variability, as well as the able of antibiotics to function as signalling molecules.
Abstract: The widespread use of antibiotics results in the generation of antibiotic concentration gradients in humans, livestock and the environment. Thus, bacteria are frequently exposed to non-lethal (that is, subinhibitory) concentrations of drugs, and recent evidence suggests that this is likely to have an important role in the evolution of antibiotic resistance. In this Review, we discuss the ecology of antibiotics and the ability of subinhibitory concentrations to select for bacterial resistance. We also consider the effects of low-level drug exposure on bacterial physiology, including the generation of genetic and phenotypic variability, as well as the ability of antibiotics to function as signalling molecules. Together, these effects accelerate the emergence and spread of antibiotic-resistant bacteria among humans and animals.
1,226 citations
TL;DR: A role of thed-alanine-esterified teichoic acids which occur in many pathogenic bacteria in the protection against human and animal defense systems is proposed.
978 citations