Abdel-Ghany, T. Received : 18 July Running workouts To Antigungal the best experience, we recommend Antifungal properties of colloidal silver use a Antifunyal up to date Antifungal properties of colloidal silver oclloidal turn off compatibility mode in Internet Explorer. For growth evaluation, treated conidia suspensions were immediately pipetted in a volume of µL onto PDA medium in 5 replicates for each variant. AgNPs displays potent activity against fully mature, preformed biofilms of C. All rights reserved.

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Antifungal properties of colloidal silver -

The best way to tackle yeast infections is to eradicate bacterial build-up, and using a promoted antifungal may get the job done quickly. Colloidal silver is thought to be a very good product to use for that purpose, especially because you don't need to use a lot at once. When you notice the yeast infection starting to subside, you'll feel relief.

Colloidal silver is highly promoted by those who believe it can purge those pathogens from your system, especially because yeast infections can be such an irritating and persistent problem.

In , a study by the Department of Microbiology at Kyungpook National University in Korea concluded that colloidal silver works as an effective antifungal after testing silver nanoparticles against the Candida fungus and observing the activity of the nanoparticles in response to the pathogens.

Lots of people believe that colloidal silver works to fight off yeast infections affecting almost any part of the body, including vaginal yeast infections, fungal ear infections, and thrush mouth. Colloidal silver is considered to be a natural remedy that can be used as a treatment for yeast infections.

This in turn implies that resistance against silver nanoparticles requires multiple independent mutations. Different mechanisms have been suggested to explain the antimicrobial property of silver nanoparticles, e.

Interestingly, various chemical procedures can be applied for the synthesis of different silver nanostructures [ 27 ]. The optical, electromagnetic, chemical, and catalytic properties of nanomaterials are strongly influenced by their morphology and structure [ 28 ].

Therefore, it is understandable that the antimicrobial properties of silver nanoparticles would depend on to their size and shape.

Baker et al. showed that high bactericidal activity could be achieved by small nanoparticles [ 27 ]. Pal et al. demonstrated that triangular silver nanoparticles had greater antibacterial properties than rod-like and spherical silver nanoparticles [ 29 ].

In another study, it was shown that silver nanowires were more toxic than silver nanospheres for alveolar epithelial cells [ 30 ]. Shape-related toxicity has been observed for gold nanoparticles, as it was found, for example, that spherical gold nanoparticles were generally more toxic than rod-shaped particles [ 31 ].

In addition, spherical gold nanoparticles had good biocompatibility, but rod gold nanoparticles were more toxic than cube form in vivo [ 32 ]. Although there are few data on antimicrobial property of different shapes of silver nanoparticles in literature [ 29—32 ], there is no information on the antifungal properties of silver and gold nanoparticles.

Hence, the purpose of the present study was to evaluate the antifungal activity of different silver and gold nanostructures nanocube, nanosphere and nanowire against isolates of Candida albicans, C. Three shapes of silver and gold nanoparticles including cubes, spheres, and wires were purchased from Zyst Fanavar Shargh Co.

ZFS Co. albicans, C. tropicalis were obtained from female patients referring to the Department of Microbiology, Pars Hospital Lab, Tehran, Iran, as well as Central Medical Lab, Yazd, Iran.

Sabouraud dextrose broth SDB , Sabouraud dextrose agar SDA , and RPMI media were provided by Invitrogen, UK, and Mueller-Hinton agar medium was obtained from Gibco, USA.

The three different silver and gold nanoparticle structures were characterized by scanning electron microscopy SEM; Hitachi S, Japan and dynamic light scattering DLS; Malvern Instruments, Italy.

In addition, the size distribution of each nanostructure was determined by Malvern Zetasizer Nano ZS apparatus at 25°C.

The three Candida species used in this study — C. tropicalis —were previously identified through the use of CHROMagar Candida plates BD Diagnostics, USA and molecular analysis by RFLP-PCR at Shiraz University of Medical Sciences, Shiraz, Iran.

Thirty isolates of each species from cases of vaginal candidiasis total of 90 test strains were included in this work. In the first step, all isolates were sub-cultured on SDA and incubated at 37°C for 24 h. Then, one colony of each isolate was added to 20 ml of SDB and incubated at 37°C for 24 h.

The Clinical and Laboratory Standards Institute CLSI microdilution method was used to determine the in vitro minimum inhibitory concentrations of the nanoparticles.

In these studies, negative controls not exposed to silver and gold nanoparticles and positive controls exposed to Nystatin were also included for comparative purposes.

The inoculated Whatman papers were placed on the agar surface, incubated at 35°C for 48 h, and finally inhibition zone diameter of each isolate was read.

All tests were carried out three times, and the values of MIC50, MIC90, and inhibition zone diameter were expressed as the mean ± standard deviation SD. For data analysis, Student's t -test was used by the SPSS software version Figure 1 shows the morphology and structure of a silver nanospheres, b silver nanowires, c silver nanocubes, d gold nanospheres, e gold nanowires and f gold nanocubes as characterized by SEM and demonstrates that the morphology of each of the three types was completely different from the others.

Nanocubes and nanospheres had the same size about 50 nm , whereas nanowires were about 50 × nm. Figure 2 shows the size distribution of a silver nanospheres, b silver nanowires, c silver nanocubes, d gold nanospheres, e gold nanowires, and f gold nanocubes, which were between 30—50 nm, — nm, 40—50 nm, 35—50 nm, — nm, and 30—50 nm, respectively, displaying their polydispersity.

The scanning electron microscopy SEM images of a silver nanospheres, b silver nanowires, c silver nanocubes, d gold nanospheres, e gold nanowires, and f gold nanocubes.

The size distribution of a silver nanospheres, b silver nanowires, c silver nanocubes, d gold nanospheres, e gold nanowires, and f gold nanocubes.

Table 1 shows the MIC50s and MIC90s of silver and gold nanostructures against the three Candida species which were obtained through the use of the CLSI microdilution method.

The highest MIC50s and MIC90s were seen with silver and gold nanowires and the lowest were observed for nanocubes.

Statistical analysis demonstrated that there were significant differences between MIC50s of nanowires vs. nanocubes, as well as nanowires vs. Similarly, there were such differences between MIC90s of nanowires vs. nanocubes and also nanowires vs. The results showed that C.

albicans isolates had lower MICs both 50 and 90 than C. tropicalis isolates had approximately comparable MICs. The MIC50 and MIC90 against different silver and gold nanostructures for different Candida isolates. In this investigation, the CLSI disk diffusion method was used to evaluate the in vitro antifungal properties of gold and silver nanostructures by measuring and recording inhibitions zones Table 2.

Inhibition zone of Candida isolates against different silver and gold nanostructures in mm. Table 3 shows the number and percentage of resistant Candida isolates against silver and gold nanostructures, respectively.

There was no resistant isolate after incubation with nanocubes for 48 h, but resistant isolates were seen with nanospheres and nanowire. tropicalis against silver nanospheres.

Although no resistant isolate was seen after incubation with nanocubes, it was noted with gold nanospheres and nanowires.

According to Table 3 , the highest percentages of resistant isolates 6. tropicalis against gold nanospheres. The number and percentage of resistant Candida isolates against silver and gold nanostructures, obtained by disk diffusion method.

Although some studies have shown that silver and gold nanoparticles have antifungal activity, there is no data on the impact of the shapes of these particles on their antifungal properties.

Therefore, the determination of antifungal activities of different silver and gold nanostructures on Candida species was the prime objective of this study.

We demonstrated, for the first time, the antifungal capabilities of silver and gold nanocubes and wires. Clearly, different nanostructures had different anticandidal activity, i. This study indicated that lower MICs and larger inhibition zones were achieved with the three forms of silver nanoparticles than with comparable gold particles.

Although no resistant isolate was observed with silver and gold nanocubes, there were some resistant isolates for other nanostructures, which was another important and new finding. Although no reports were found on the antifungal properties of the shapes of silver and gold nanoparticles explored in the present investigation, there were some comparative papers on the antimicrobial properties of different nanostructures.

Their study was the first comparative work on the antibacterial properties of different shapes of silver nanoparticles [ 29 ]. Stoehr et al. found that silver nanowires length: 1. These authors declared that shape is an important factor in nanotoxicological investigations, and must be studied further.

Albanese et al. implied in their review article that the size and shape of nanomaterials affected biological kinetics, transportation, and toxicity, both in vitro and in vivo [ 33 ].

Consistent with silver nanoparticles, the shape of gold nanoparticles is also important for as it has been seen that spherical gold nanoparticles were more toxic than rod-shaped nanoparticles [ 31 ].

On the other hand, spherical gold nanoparticles had high biocompatibility, but gold nanorods were more toxic than cube-shaped ones in vivo [ 32 ]. Several reasons can be proposed for differences in the antifungal property of different nanostructures shapes. A second reason is the different chemical activities of nanostructures which depend on their size and shape.

Silver and gold nanocubes have 12 edges, but nanospheres and nanowires have no edge, and perhaps the presence of the edges affects their activity. The third factor could be the different ion release properties because it has been found that silver and gold nanoparticles release ions [ 34 ] that lead to cell damage or cell death.

In addition, studies on the mechanism of toxic activity of silver and gold ions on different cells showed that metal ions can damage DNA, inhibit replication, disturb cellular or membrane proteins, and decrease production of ATP [ 35 , 36 ].

Although the mechanism of antimicrobial property of silver and gold nanostructures is still not well understood, there are some investigations that indicate that silver nanoparticles are broadly similar to silver ions, and can damage membranes, inhibit cellular respiratory enzymes, and inactivate DNA [ 16 , 22 , 25 , 26 ].

Total Environ. Konopka, J. One health: Fungal pathogens of humans, animals, and plants. Washington: American Academy of Microbiology. Lara, H. Effect of silver nanoparticles on Candida albicans biofilms: An ultrastructural study. Nanobiotechnology 13, Le, A. Powerful colloidal silver nanoparticles for the prevention of gastrointestinal bacterial infections.

Li, Y. Surface-coating-dependent dissolution, aggregation, and reactive oxygen species ROS generation of silver nanoparticles under different irradiation conditions.

Lin, Y. Recent developments of metal-based compounds against fungal pathogens. Longhi, C. Combination of fluconazole with silver nanoparticles produced by Fusarium oxysporum improves antifungal effect against planktonic cells and biofilm of drug-resistant Candida albicans.

Lotfy, W. Biosynthesis of silver nanoparticles by Aspergillus terreus: Characterization, optimization, and biological activities. Madeo, F. Oxygen stress: A regulator of apoptosis in yeast.

Cell Biol. Mani Chandrika, K. Promising antifungal agents: A minireview. Marcato, P. Biogenic silver nanoparticles and its antifungal activity as a new topical transungual drug. Mondal, A. Anti-bacterial and anti-candidal activity of silver nanoparticles biosynthesized using citrobacter spp.

Ms5 culture supernatant. Biomolecules 10, — Monteiro, D. Silver nanoparticles: Influence of stabilizing agent and diameter on antifungal activity against Candida albicans and Candida glabrata biofilms.

Mosleh-Shirazi, S. Renal clearable nanoparticles: An expanding horizon for improving biomedical imaging and cancer therapy.

Today Commun. A , Mujaddidi, N. Pharmacological properties of biogenically synthesized silver nanoparticles using endophyte Bacillus cereus extract of Berberis lyceum against oxidative stress and pathogenic multidrug-resistant bacteria. Saudi J. Mussin, J. Antimicrobial and cytotoxic activity of green synthesis silver nanoparticles targeting skin and soft tissue infectious agents.

Antifungal activity of silver nanoparticles in combination with ketoconazole against Malassezia furfur. Express 9, — Editors P. Chong, and D. Newman D.

Steinmacher , — Padalia, H. Green synthesis of silver nanoparticles from marigold flower and its synergistic antimicrobial potential.

Parthiban, E. Green synthesis of silver-nanoparticles from Annona reticulata leaves aqueous extract and its mosquito larvicidal and anti-microbial activity on human pathogens.

Patra, J. Antibacterial activity and synergistic antibacterial potential of biosynthesized silver nanoparticles against foodborne pathogenic bacteria along with its anticandidal and antioxidant effects.

Pereira, L. Synthesis, characterization and antifungal activity of chemically and fungal-produced silver nanoparticles against Trichophyton rubrum. Qian, Y. Biosynthesis of silver nanoparticles by the endophytic fungus Epicoccum nigrum and their activity against pathogenic fungi.

Bioprocess Biosyst. Quinteros, M. Biogenic nanoparticles: Synthesis, stability and biocompatibility mediated by proteins of Pseudomonas aeruginosa. Radhakrishnan, V. Silver nanoparticles induced alterations in multiple cellular targets, which are critical for drug susceptibilities and pathogenicity in fungal pathogen Candida albicans.

Nanomedicine 13, — Rai, M. Silver nanoparticles as a new generation of antimicrobials. Różalska, B. Biogenic nanosilver synthesized in Metarhizium robertsii waste mycelium extract — as a modulator of Candida albicans morphogenesis, membrane lipidome and biofilm. PLoS One 13, —e Rozhin, A.

Biogenic silver nanoparticles: Synthesis and application as antibacterial and antifungal agents. Micromachines 12, Ruta, L. Accumulation of Ag I by Saccharomyces cerevisiae cells expressing plant metallothioneins.

Cells 7, Sadeghipour, Y. Evaluation antibacterial activity of biosynthesized silver nanoparticles using e euphorbia pseudocactus berger extracts Euphorbiaceae.

Nanomedicine Res. Salati, S. The biological synthesis of silver nanoparticles by mango plant extract and its anti-candida effects. Salem, S. Pseudomonas indica-mediated silver nanoparticles: Antifungal and antioxidant biogenic tool for suppressing mucormycosis fungi.

Sharifi-Rad, M. Synthesis of biogenic silver nanoparticles Agcl-nps using a pulicaria vulgaris gaertn. aerial part extract and their application as antibacterial, antifungal and antioxidant agents.

Nanomaterials 10, — Siddiqi, K. A review on biosynthesis of silver nanoparticles and their biocidal properties.

Nanobiotechnology 16, Soares, M. Biosynthesis of silver nanoparticles using Caesalpinia ferrea Tul. Martius extract: Physicochemical characterization, antifungal activity and cytotoxicity. PeerJ 6, —e Song, J. Rapid biological synthesis of silver nanoparticles using plant leaf extracts.

Spagnoletti, F. Protein corona on biogenic silver nanoparticles provides higher stability and protects cells from toxicity in comparison to chemical nanoparticles. Stensberg, M. Toxicological studies on silver nanoparticles: Challenges and opportunities in assessment, monitoring and imaging.

Nanomedicine 6, — Terzioğlu, E. Genomic, transcriptomic and physiological analyses of silver-resistant Saccharomyces cerevisiae obtained by evolutionary engineering. Yeast 37, — Vagabov, V. Efflux of potassium ions from cells and spheroplasts of Saccharomyces cerevisiae yeast treated with silver and copper ions.

Valsalam, S. Rapid biosynthesis and characterization of silver nanoparticles from the leaf extract of Tropaeolum majus L. and its enhanced in-vitro antibacterial, antifungal, antioxidant and anticancer properties. B Biol. Vanlalveni, C. Green synthesis of silver nanoparticles using nostoc linckia and its antimicrobial activity: A novel biological approach.

Bionanoscience 8, — Vazquez-Muñoz, R. Ultrastructural analysis of candida albicans when exposed to silver nanoparticles.

PLoS One 9, —e Vest, K. Copper import into the mitochondrial matrix in Saccharomyces cerevisiae is mediated by Pic2, a mitochondrial carrier family protein.

Candida auris is propertes emergent Antifungal properties of colloidal silver pathogenic silevr with an unprecedented ability for a fungal organism to easily spread between Zilver in clinical settings, leading to major pro;erties in healthcare facilities. Chromium browser advantages formation of biofilms by C. auris contributes to infection and its environmental persistence. Most antifungals and sanitizing procedures are not effective against C. aurisbut antimicrobial nanomaterials could represent a viable alternative to combat the infections caused by this emerging pathogen. We have previously described an easy and inexpensive method to synthesize silver nanoparticles AgNPs in non-specialized laboratories. Here, we have assessed the antimicrobial activity of the resulting AgNPs on C. Oral ingestion: Colloidal silver can Enhancing stamina with pre-workout nutrition ingested Antifungal properties of colloidal silver porperties drinking it directly Antifungal properties of colloidal silver the bottle Spiritual healing techniques by mixing colloival with water or juice. Topical application: Colloidal silver can be propertiew topically to the skin Angifungal treat various skin conditions, including wounds, burns, and infections. It can be applied directly to the affected area or mixed with a carrier oil such as coconut oil or olive oil. Nasal spray: Colloidal silver can be used as a nasal spray to treat sinus infections and other respiratory conditions. Eye drops: Colloidal silver can be used as eye drops to treat eye infections such as pink eye or styes.

Antifungal properties of colloidal silver -

Overuse or prolonged use of colloidal silver can cause argyria, a condition in which the skin turns blue-gray due to the accumulation of silver particles. Consult with a healthcare provider before taking colloidal silver, especially if you have any underlying medical conditions or are taking medication.

Colloidal silver is a suspension of tiny silver particles in a liquid, typically water. It is often marketed as a dietary supplement or alternative medicine and is used for its supposed health benefits. The silver particles in colloidal silver are typically between 1 and nanometers in size, and their concentration can vary depending on the product.

Colloidal silver can be made using various methods, such as electrolysis, chemical reduction, or ultrasonic methods. Colloidal silver has been used for centuries as a natural antimicrobial agent and is believed to have antibacterial, antiviral, and antifungal properties.

However, its effectiveness and safety remain somewhat controversial, and the US Food and Drug Administration FDA has not approved it for any medical use.

Here are some potential benefits of colloidal silver: Antibacterial properties: Colloidal silver has potent antibacterial properties and has been used to treat various bacterial infections, including wound infections, ear infections, and sinus infections.

Antiviral properties: Colloidal silver has also been shown to have antiviral properties, making it a potential treatment for viral infections such as the common cold, flu, and herpes.

Anti-inflammatory properties: Colloidal silver may help reduce inflammation and alleviate symptoms of inflammatory conditions such as arthritis and asthma. Skin health: Colloidal silver has been used to treat skin conditions such as acne, eczema, and psoriasis. auris strains, with IC 50 values ranging from 1.

Overall, our results indicate potent activity of AgNPs against strains of C. auris , both under planktonic and biofilm growing conditions, and indicate that AgNPs may contribute to the control of infections caused by this emerging nosocomial threat.

Candida auris is an emergent multidrug-resistant yeast that has been reported worldwide since its detection in Japan in Centers for Disease Control and Prevention, It has been determined that there are four geographic clades of this pathogen, including South Asian clade I , East Asian clade II , South African clade III , and South American clade IV , which interestingly seemed to have emerged independently in different regions of the world at the same time Jeffery-Smith et al.

auris is described as an ovoid-shaped non-dimorphic yeast that rarely forms pseudohyphae and exhibits two growing typical phenotypes: aggregative and non-aggregative Ku et al.

auris spreads in healthcare settings, posing a risk for hospital patients due to its high mortality rate invasive infections and its healthcare-associated outbreaks Sears and Schwartz, ; Forsberg et al. It easily contaminates surfaces and medical instrumentation within healthcare facilities for long periods, which poses a risk factor in healthcare facilities worldwide Sears and Schwartz, Currently, the prevention and treatment of C.

auris are challenging due to several factors. Additionally, it is commonly misidentified in clinical laboratories, often leading to inappropriate treatments. Furthermore, it is able to form biofilms, C. auris biofilms, besides being intrinsically resistant to all antifungal agents Sherry et al.

This yeast is highly resistant to current sanitation processes and treatments, such as UV light and quaternary ammonium compounds Ku et al.

Therefore, new treatments are needed to prevent and control C. auris growth and dissemination. Nanotechnology can provide new cost-effective antimicrobial nanomaterials nanoantibiotics that work as disinfectants and antimicrobial drugs.

In particular, silver nanoparticles AgNPs exhibit good antimicrobial properties with a wide range of action against a broad range of microorganisms, including several Candida species Raghunath and Perumal, ; Vazquez-Muñoz et al.

Additionally, nanoantibiotics can overcome the microbial drug-resistance to antibiotics Rudramurthy et al. However, to date, only one report from our group has described the effect of AgNPs synthesized using a different method against a single isolate of C.

auris in suspension and on functionalized medical and environmental surfaces Lara et al. This study demonstrated that AgNPs effectively inhibit the C. auris biofilm formation. Additionally, a non-nanostructured silver commercial formulation [0. auris Biswal et al.

We have recently reported on a modified facile, inexpensive synthetic method to generate AgNPs in non-specialized laboratories and described their antibacterial and antifungal properties. We hypothesize that AgNPs display strong antifungal activity against multiple strains of C.

auris , regardless of their clade, antibiotic-resistant profile, or morphological traits. Therefore, the objective of this study was to assess the antimicrobial activity of AgNPs synthesized using our newly described method, on different C.

auris strains, for which we have evaluated the antimicrobial activity of nanoantibiotics against 10 C. auris strains from the CDC panel, representing the four different major clades, both under planktonic and biofilm growing conditions. Roswell Park Memorial Institute RPMI culture medium, phosphate saline buffer PBS , 2,3-bis 2-methoxynitrosulfophenyl -2H-tetrazoliumcarboxanilide salt XTT 0.

Solutions of the different reagents were prepared in Milli-Q water. AgNPs coated with polyvinylpyrrolidone PVP were synthesized by a chemical reduction protocol, reported previously by our group Vazquez-Muñoz et al. The synthesis method uses a simple and fast chemical reduction process that involves the addition of PVP to a warmed AgNO 3 solution, followed by sodium borohydride.

The AgNPs obtained have an aspect ratio close to 1, an average size of 6. The negatively-charged, small, spheroid AgNPs displayed the strong antimicrobial activity against Staphylococcus aureus and Candida albicans Vazquez-Muñoz et al.

This easy-to-replicate-synthesis method was specifically developed so that it can be readily implemented in non-specialized facilities and laboratories. auris strains were acquired from the CDC antimicrobial resistance AR Isolate Bank stock CDC, b.

The following AR bank strains were used: clade I , , , , and , clade II , clade III and , and clade IV and Frozen glycerol stocks of the microbial cells were subcultured onto Yeast extract-Peptone-Dextrose YPD BD Difco, MD, USA agar plates, for 48 h at 37°C. Then, C. auris was cultured into YPD liquid media overnight at 30°C, in an orbital shaker.

Cells from these cultures were prepared for the susceptibility tests, as described in the following sections. The antimicrobial activity of the nanoparticles on the C. auris planktonic cells was determined by following the guidelines from the CLSI M27 protocol CLSI, for Candida species, with minor modifications.

Then, 50 μl of the C. auris strains was inoculated in 96 multi-well round-bottom plates Corning Inc. AgNPs were prepared in a two-fold dilution series in RPMI, and then 50 μl of the dilution series was added to the plates with the yeast, for final AgNPs concentration range from 0.

Plates were incubated at 35°C for 48 h. The minimal inhibitory concentration MIC was set as the concentration in the well at which no microbial growth — turbidity or microbial pellet formation — were observed, as suggested by the CLSI guidelines.

The minimal fungicidal concentration MFC was also established, as follows: after reading the MIC in each plate, 10 μl from each well containing the untreated and treated microbial cells was reinoculated in YPD agar plates and incubated for 24 h at 37°C.

To ensure reproducibility, the experiment was independently performed by two people, on separate days, using different batches of AgNPs and C. auris cultures. Experiments were performed using duplicates of the plates, which contained triplicates of each condition. The antibiofilm activity of AgNPs was evaluated in both the biofilm formation phase and on the preformed biofilm, as previously reported by our group Pierce et al.

For inhibition of biofilm formation, overnight cultures of C. Fifty microliter of the adjusted cell suspension was transferred to 96 multi-well flat-bottom plates Corning Inc. Then, 50 μl of AgNPs prepared in a two-fold dilution series was added into multi-well plates, for a final concentration range from 0.

The plates were then incubated at 37°C for 24 h to allow for biofilm formation. We also tested the activity against preformed biofilms. Then, μl of the microbial suspension was inoculated into multi-well plates, and then incubated for 24 h at 37°C.

After incubation, the preformed biofilms were washed twice in PBS. Finally, the plates were incubated at 37°C for an additional 24 h. The AgNPs anti-biofilm activity was determined using the XTT colorimetric method Pierce et al.

Plates were protected from light and incubated at 37°C for 2 h. To verify the reproducibility of the antibiofilm activity, the experiment was independently repeated by two different people.

AgNPs from different rounds of syntheses were tested using two replicates of multi-well plates, each with three replicates of the treatments.

We assessed the effect of AgNPs on the biofilm structure in all C. auris strains from the four clades, using the biofilm inhibition assays. The biofilms were treated with sublethal yet still inhibitory concentrations of AgNPs.

Treated and untreated control biofilms structural analysis was performed using optical and scanning electron microscopy. Biofilms were washed twice with PBS, and then fixed with a 2.

For the optical microscopy observations, the glutaraldehyde-fixed biofilms were observed under a × magnification using the bright field mode, in an inverted optical microscope Fisher Scientific. Finally, the ethanol was completely removed, and the dried samples were coated with gold, with 25 mA current for 3 min, in a sputter coater SC Quorum Technologies.

The gold-coated biofilms were observed in a TMPlus scanning electron microscope SEM Hitachi Inc. The samples were prepared in duplicates, and different fields of both replicates from each sample were observed.

AgNPs exerted the strong antimicrobial activity against all the C. auris strains growing under planktonic conditions. AgNPs MIC and MFC values against each strain are summarized in Table 1. Table 1. AgNPs exhibited a strong activity to prevent biofilm formation in C.

auris , regardless of the clade. Figure 1 shows the biofilm-inhibitory effect against representative isolates from each clade, including strains AR clade I , clade III , clade IV , and clade II.

The AgNPs antibiofilm activity against all 10 strains tested is shown in Supplementary Figure S1A. The calculated IC 50 values were ranged from 0. These results indicate that AgNPs exert a potent activity for the prevention of biofilm formation by the different C.

auris strains. Figure 1. Silver nanoparticles AgNPs inhibit the biofilm formation on C. The dose-response curves show that AgNPs display potent inhibitory activity expressed as XTT readings against the C.

auris AR clade I , clade III , clade IV , and clade II strains during the biofilm formation phase. Table 2. Calculated IC 50 values for AgNPs against C. auris biofilms by the different strains. Interestingly, we observed that some strains exhibited a significant increase in the biofilm activity determined by the XTT readings when grown in the presence of very low concentrations of AgNPs.

This effect was consistently observed in all replicates, although with different degrees of intensity. To the extent of our knowledge, this phenomenon has not been observed in yeasts treated with AgNPs, but it has been previously reported in bacteria Kumar-Krishnan et al.

Nevertheless, this increase in activity is promptly extinguished at just slightly higher concentrations of AgNPs. Additionally, to assess if the augmented activity was specific to the AgNPs, we evaluated the influence of AgNO 3 on the C.

auris AR strain, under the same culture conditions used for the AgNPs susceptibility assays. We observed an increase in the biofilm activity in subinhibitory concentrations of silver ions Supplementary Figure S2.

AgNPs displays potent activity against fully mature, preformed biofilms of C. auris , irrespective of their clade, as observed for representative isolates AR clade I , clade III , clade IV , and clade II Figure 2. The AgNPs activity on the preformed biofilms from all 10 C.

auris strains tested is shown in Supplementary Figure S1B. From the dose-response experiments, the resulting calculated IC 50 values of AgNPs against preformed biofilms of the different C. auris strains were ranged from 1. As with the biofilm-inhibitory assays described before, we also observed an increase in the biofilm activity determined by the XTT readings at very low AgNPs concentrations Figure 2 ; Supplementary Figure S2.

Figure 2. Antibiofilm activity of AgNPs against C. auris preformed biofilms. The dose-response curves show that AgNPs display potent inhibitory activity expressed as the XTT readings against preformed biofilms of the C. auris AR from clade I A , from clade III B , from clade IV C , and from clade II D strains.

Once we had established the activity of AgNPs against C. auris biofilms, we were interested in the visualization of the effects of treatment with these nanoantibiotics exerted on the overall biofilm structure, as well as on individual cells within the biofilms.

Thus, in another set of experiments, we grew biofilms of the all different C. auris strains in the presence of subinhibitory concentrations of the AgNPs, with results for a representative strain from each clade shown in Figures 2 — 5 , corresponding to strains East Asia clade , Africa clade , South America clade , and South Asia clade , respectively.

Optical microscopy revealed that AgNPs decrease the ability of C. auris to form biofilms. As seen in Supplementary Figure S3 , in the untreated control samples, biofilms formed by the different strains uniformly covered most of the bottom of the wells in the microtiter plates.

In contrast, inhibitory concentrations of AgNPs disrupt the biofilm formation in all C. auris strains, as revealed by the noticeable reduction of the coverage area of biofilms on the bottom of the wells. At higher concentrations of AgNPs, biofilm formation was drastically reduced, with only isolated cells scattered on the bottom of the wells being visible under the microscope.

The biofilms were observed using SEM at low × and high 2,× magnifications, to further determine the effect of treatment with AgNPs on the biofilm structure and the cell morphology.

auris strains from the distinct clades display differences in the cell morphology and the biofilm organization. SEM images confirmed that exposure to inhibitory concentrations of AgNPs decreases the biofilm forming ability of the different C.

auris strains Figures 3 — 6 ; Supplementary Figure S4. SEM micrographs showed that untreated biofilms display a uniform distribution with a tight clustering of cells; in contrast, AgNPs-treated biofilms cover a noticeably lesser area, and the cells appear to be less clustered.

This finding is similar to that reported recently by Lara et al. auris strain when exposed to a different type of AgNPs Lara et al. Figure 3. AgNPs affect biofilm structure and cellular morphology of C.

auris strain Scanning electron microscope SEM micrographs reveal that untreated biofilms have a larger area of distribution A than the AgNPs-treated biofilms B,C. Also, the shape and size of the cells are affected by the AgNPs E,F , whereas the untreated biofilms remain unaltered D.

Figure 4. AgNPs reduce biofilm formation of C. SEM micrographs show a noticeable reduction in the biofilm formation in the AgNPs-treated biofilms B,C when contrasted with the untreated biofilms A.

However, the impact on cell morphology appears to be minimal E,F , as the cell shape and size of cells within the treated biofilms are similar to those of the untreated control D.

Figure 5. SEM micrographs show that biofilms and individual cell morphology are drastically affected by the AgNPs. Treated biofilms B,C show an evident decrease in coverage area as compared to untreated biofilms A , whereas the cell morphology is changed by treatment with AgNPs E,F as compared to cells in untreated biofilms D.

Figure 6. The SEM micrographs of C. auris strain reveal that untreated biofilms A display a larger area of coverage than the AgNPs-treated biofilms B,C. Moreover, untreated cells display pseudohyphae-like shape D , which is also observed at the lowest concentration of AgNPs E , but higher concentrations of AgNPs induce an aberrant morphology on cells and reduce the cell separation process F as compared to cells in untreated biofilms D.

Moreover, when observed at higher magnification, it was revealed that treatment with AgNPs damages the fungal cell structure. In the control untreated samples, cells within the biofilms formed by strains Figure 3 , Figure 4 , and Figure 5 displayed a typical oval yeast shape, whereas those in biofilms formed by strain Figure 6 mostly exhibited a more elongated almost pseudohyphal morphology.

For all the strains, inhibitory concentrations of AgNPs caused alterations in the shape and size of individual cells within the biofilms with also less cell clustering observed. In the case of C. auris strain , low concentrations of AgNPs induced elongation of the shape in the yeast cells, similar to the pseudohyphae.

In contrast, in the C. auris strain , low concentrations of AgNPs induce enlargement of the pseudohyphae-shaped cells, growing longer than in the control Figure 6 , and their presence appears to be relatively higher. However, at higher concentrations of AgNPs, the cells of this strain become yeast-shaped again but with aberrant morphology.

Also, in several instances, yeast cells remained attached to each other after cell division, leading to the formation of small multibranched chains of cells, typically in groups of less than 10 cells.

Supplementary Figure S3 includes SEM observations for the reminder of C. auris strains, with similar effects on biofilm structure and cellular morphology Supplementary Figure S4. Our results show that AgNPs display potent antifungal activity at very low concentrations in virtually all C.

AR is the only strain from clade II and might have particular biological mechanisms that allow it to withstand the AgNPs killing effect, even when its growth is still prevented at very low concentrations of AgNPs.

In a previous report Vazquez-Muñoz et al. The MIC for S. It is worth noting that all C. auris strains are more susceptible to the AgNPs than C. albicans tested under similar experimental conditions. Also, the anti- Candidal activity of these AgNPs against planktonic cells of C. Moreover, all C. auris strains tested here displayed susceptibility to AgNPs, irrespective of their growth characteristics, susceptibility profiles against conventional antifungal, geographical origin clade , or their ability to form aggregates in planktonic in vitro cultures.

Moreover, the aggregating phenotype may be associated with their drug susceptibility Szekely et al. This has been observed in other microorganisms, including other Candida species, where the drug-resistant strains and drug-sensitive strains from the same species display a similar susceptibility MIC value to AgNPs Romero-Urbina et al.

Additionally, our results suggest that AgNPs antimicrobial performance is better than the main antifungals on all the tested C. auris CDC AR strains, according to their antifungal susceptibility profile reported by the CDC CDC, Although there are not established MIC breakpoints for the main available antifungals against C.

This may be due to the proposed mechanisms of action of AgNPs. The mechanism of action of the antifungal drugs is linked to specific molecular targets that disrupt the cell metabolism or structure, affecting growth. In response to these stresses, specific but relatively small changes at the structural or molecular level may increase their probability to resist the action of antifungals, as previously described for C.

auris Krishnasamy et al. In contrast, AgNPs cause several simultaneous types of structural and metabolic damages in the Candida cells, such as membrane depolarization Zamperini et al. This massive disruption of cellular structure and function reduces their ability to withstand the AgNPs effects.

auris strains are exposed to AgNPs. auris is capable of forming biofilms that improve their adherence to surfaces Forsberg et al. The mechanisms that enhance their resistance are mostly unknown, but some factors are known to help C. auris withstand harsh conditions include the protection by matrix polysaccharides Dominguez et al.

Thus, the formation of C. auris biofilms represents a current threat to both individual patients and healthcare facilities Sears and Schwartz, In previous work, we demonstrated the antimicrobial activity of the AgNPs on the planktonic stage of C.

albicans Vazquez-Muñoz et al. In this work, we evaluate the anti-biofilm activity of the AgNPs during the biofilm formation phase and against fully mature, preformed biofilms. Our results show that AgNPs exert a potent activity for the prevention of biofilm formation by the different C.

auris strains, regardless of the clade. Interestingly, these values are only slightly higher than the MIC values obtained under planktonic growth.

These values also compare favorably to those described before for conventional antifungals against biofilm formation for some of the same C. auris strains Dekkerová et al. We note that the AgNPs IC 50 value for the C. auris AR strain is higher than the value reported for the same strain as reported by Lara et al.

Also, the antibiofilm activity of our AgNPs is comparable to the activity described for AgNPs synthesized using different methods against other Candida species Lara et al.

Regarding the increase in the biofilm activity at very low concentrations of AgNPs, this effect on the biofilm activity must be addressed in further studies, to assess any potential disadvantage of low-silver-content products intended against C.

auris biofilms. As mentioned above, there are commercially available products containing silver Biswal et al. It is well-known that once a biofilm is established, Candidal cells within these biofilms display increased susceptibility to most clinically-used antifungal agents Ramage et al.

This is particularly true in the case of C. auris biofilms, which are intrinsically resistant to all the three main classes of antifungals polyenes, azoles, and echinocandins as well as to physical and chemical sanitizing methods Sherry et al.

AgNPs displayed potent activity against fully mature, preformed biofilms of all C. Interestingly, these values are similar typically within one-fold dilution to those observed for the same strains in the case of biofilm inhibition compare values in both columns of Table 2.

Therefore, in stark contrast with conventional antifungal agents, the AgNPs potency does not seem to be particularly reduced after the biofilm has reached maturity.

Moreover, the AgNPs antifungal activity against the preformed biofilms is equivalent or even better to that of conventional antifungals. For the C. Overall, although multiple mechanisms confer resistance of cells within biofilms against conventional antifungal agents Srinivasan et al.

The observed effects of AgNPs on cellular morphology merit some further discussions. These effects seem to be clade-related, based on our SEM analysis for the 10 strains included in this study.

Antifungal properties of colloidal silver colloidwl years, an increase in multidrug-resistant fungal strains has been Antifungal properties of colloidal silver, propsrties, together propertiee the limited number of clinically available Anttifungal agents, highlights the Weight and nutritional analysis for the development of new antifungal agents. Due propertiez the Antifungal properties of colloidal silver propfrties activity of silver silvef AgNPsthere is a growing interest in their use in Boost insulin sensitivity treatment collokdal fungal infections. Nanoparticles are usually synthesised through a variety of physical and chemical processes that are costly and pollute the environment. For this reason, biogenic synthesis is emerging as an environmentally friendly technology and new strategies are increasingly based on the use of biogenic AgNPs as antifungal agents for clinical use. The aim of this review is to compare the antifungal activity of different biogenic AgNPs and to summarise the current knowledge on the mechanisms of action and resistance of fungi to AgNPs. Finally, a general analysis of the toxicity of biogenic AgNPs in human and veterinary medicine is performed. In recent decades, fungal infections have increased and become a major public health threat.