Mature Candida Research Articles

Electrophysiological and olfactory behavioural responses of mature Stilpnotia candida to a mixture of volatiles from Populus×beijingensis

Electrophysiological and olfactory behavioural responses of mature Stilpnotia candida to a mixture of volatiles from Populus×beijingensis

Quinalizarin as a potential antifungal drug for the treatment of Candida albicans fungal infection in cancer patients.

This study aims to analyze the antifungal properties of quinalizarin, a plant-derived compound with proven anticancer effects. Quinalizarin exhibited antifungal activity against opportunistic pathogenic Candida species and Geotrichum capitatum. The treatment with this anthraquinone reduced hyphal growth, inhibited biofilm formation, and damaged mature Candida albicans biofilms. Real-time RT-PCR revealed that quinalizarin downregulated the expression of hyphae-related and biofilm-specific genes. The flow cytometry method used in the study showed that both apoptosis and necrosis were the physiological mechanisms of quinalizarin-induced C. albicans cell death, depending on the dose of the antifungal agent. A further study revealed an increase in the levels of intracellular reactive oxygen species and alterations in mitochondrial membrane potential after treatment with quinalizarin. Finally, quinalizarin was found to have low toxicity in a hemolytic test using human erythrocytes. In conclusion, we have identified quinalizarin as a potential antifungal compound.IMPORTANCEThis article is a study to determine the antifungal activity of quinalizarin (1,2,5,8-tetrahydroxyanthraquinone). Quinalizarin has potential antitumor properties and is effective in different types of tumor cells. The aim of the present study was to prove that quinalizarin can be used simultaneously in the treatment of cancer and in the treatment of intercurrent fungal infections. Quinalizarin was identified as a novel antifungal compound with low toxicity. These results may contribute to the development of a new drug with dual activity in the treatment of cancer-associated candidiasis.

Screening of Antimicrobial, Antibiofilm, and Cytotoxic Activities of Some Medicinal Plants from Balıkesir Province, Türkiye: Potential Effects of Allium paniculatum Flower.

Plant extracts are important natural resources that may have antimicrobial and antibiofilm effects against pathogens. This study was conducted to investigate the in vitro antimicrobial activities of methanol extracts of some medicinal plants (Achillea nobilis subspecies neilreichii (A. Kern.) Velen., Aetheorhiza bulbosa (L.) Cass, Allium paniculatum L, Asphodelus aestivus Brot., Ballota nigra L., Cistus laurifolius L., Cistus salviifolius L., Dioscorea communis (L.) Caddick and Wilkin, Galium verum L., Hypericum triquetrifolium Turra, Paliurus spina-christi Mill., Primula vulgaris Huds. subspecies rubra (Sm.) Arcang., Ranunculus arvensis L. and Teucrium polium L.) from Balıkesir province in Türkiye. Preliminary antimicrobial activity screening was conducted for all extracts. Antibiofilm activity studies were conducted on mature Candida albicans biofilms. Moreover, the cytotoxicities of A. paniculatum flower extract on A549 and Vero cell lines were determined using a colorimetric tetrazolium-based assay. A. paniculatum flower, P. vulgaris root, C. laurifolius, C. salviifolius, and A. nobilis displayed good activity [minimum inhibitory concentrations (MIC): 9.75, 156, 312, 312 and 312 μg/mL, respectively] against C. albicans American Type Culture Collection 10231. Biofilm studies were conducted on these plant extracts. The methanol extract of A. paniculatum flower decreased the number of C. albicans [colony-forming unit (CFU)/mL] in mature biofilm statistically at 32 x MIC and higher concentrations (p < 0.01). A. paniculatum flower extract had a cytotoxic effect (killing more than 50% of cells) at high concentrations, and its effect on Vero cells was similar to that on A549 cells. This study demonstrated the importance of the methanol extract of A. paniculatum flower as a natural alternative against C. albicans infections, including biofilms.

Susceptibility of Candida albicans, Staphylococcus aureus and Escherichia coli to Extracts of Mango (Magnifera indica)

Aim: This study was carried out to investigate the Susceptibility of Candida albicans, Staphylococcus aureus and Escherichia coli to extracts from young and mature mango (Magnifera indica) leaves and stem-bark of the same plant. &#x0D; Study Design: The study employed statistical analysis of the data and interpretation. &#x0D; Place and Duration of Study: Young and mature mango leaves and stem-barks were collected from the Botanical Garden, Kenule Beeson Saro-Wiwa Polytechnic, Bori, Nigeria, and taken to the laboratory for analyses. &#x0D; Methodology: The samples were dried in an oven at 80oC for 3 days. Thereafter, 50 g of each ground mango leaves and stem-bark (young and mature of the same plant) were soaked separately in 500 ml of water, ethanol (95% v/v), and acetic acid (99.9% v/v) for another 3 days. The soaked materials were filtered through Whatman No. 1 filter paper into sterile beakers and evaporated to dryness in a water-bath at 80oC. The dried extracts obtained were reconstituted with water at concentrations of 100, 75, 50 and 25 mg/ml. Test organisms, Candida albicans, Staphylococcus aureus and Escherichia coli were obtained after proper laboratory screening of isolates from the diagnostic laboratory of the Rivers State University Teaching Hospital, Port Harcourt, Nigeria, for confirmation of identity and storage in universal bottles in a refrigerator. Sensitivity tests were carried out with the agar well diffusion method against the test organisms, using tetracycline as standard control drug (for bacteria) and fluconazole (for Candida), with cultures incubated accordingly. The measured zones of inhibition were compared with the controls and interpreted as resistant, intermediate, or susceptible to mango extracts in accordance with the interpretive guidelines published by the National Committee for Clinical Laboratory Standards (NCCLS). Assays for minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were also carried out.&#x0D; Results: Results obtained showed that Escherichia coli was completely susceptible to acetic acid young leaf and young bark extracts at 100 mg/ml concentrations. Staphylococcus aureus was susceptible only to Acetic acid young leaf extract at 100 mg/ml. For Candida albicans complete susceptibility was with acetic acid young bark at 100 mg/ml. mature leaf extract (100 mg/ml ), acetic acid young bark extract (100 to 50 mg/ml ), aqueous young bark extract (100 mg/ml) and acetic acid mature Candida albicans was susceptible to acetic acid young and mature bark extract at 100 mg/ml concentration. Minimum inhibitory concentration (MIC) values of acetic acid young leaf extract for all three organisms were 12.5 mg/ml. MIC of ethanolic young leaf extract for E. coli was 12.5 mg/ml whereas that for C. albicans was 50 mg/ml. Minimum bacteriocidal concentration values were same as MIC.&#x0D; Conclusion: E. coli and S.aureus were found to be most susceptible to acetic acid young leaf and stem-bark mango extracts. For C. albicans susceptibility profiles were best with aceti acid young and mature stem-bark extracts. It was also found that mango phytochemicals have broad-spectrum antibacterial activity as well as antifungal properties. The study also reveals that young mango parts contain higher bioactive substances than mature parts. Finally, it was concluded that acetic acid extracts produced the highest antimicrobial effects whereas aqueous extracts produced the least.

Azole-Based Compounds That Are Active against Candida Biofilm: In Vitro, In Vivo and In Silico Studies.

Fungal pathogens, including Candida spp., Aspergillus spp. and dermatophytes, cause more than a billion human infections every year. A large library of imidazole- and triazole-based compounds were in vitro screened for their antifungal activity against C. albicans, C. glabrata, C. krusei, A. fumigatus and dermatophytes, such as Microsporum gypseum, Trichophyton rubrum and Trichophyton mentagrophytes. The imidazole carbamate 12 emerged as the most active compound, showing a valuable antifungal activity against C. glabrata (MIC 1–16 μg/mL) and C. krusei (MIC 4–24 μg/mL). No activity against A. fumigatus or the dermatophytes was observed among all the tested compounds. The compound 12 inhibited the formation of C. albicans, C. glabrata and C. krusei biofilms and reduced the mature Candida biofilm. In the Galleria mellonella larvae, 12 showed a significant reduction in the Candida infection, together with a lack of toxicity at the concentration used to activate its antifungal activity. Moreover, the in silico prediction of the putative targets revealed that the concurrent presence of the imidazole core, the carbamate and the p-chlorophenyl is important for providing a strong affinity for lanosterol 14α-demethylase (CgCYP51a1) and the fungal carbonic anhydrase (CgNce103), the S-enantiomer being more productive in these interactions.

Vapor-Phase of Essential Oils as a Promising Solution to Prevent Candida Vaginal Biofilms Caused by Antifungal Resistant Strains.

Background: Vulvovaginal candidiasis (VVC) is a disease with high incidence, a huge impact on the quality of life and health of women, and which represents a great challenge to treat. The growing need to apply antifungal intensive therapies have contributed to an emergence of drug-resistant Candida strains. Thus, effective therapeutic options, to meet the antifungal-resistance challenge and to control high resilient biofilms, are urgently needed. This study aimed to investigate the antifungal activity of essentials oils (EOs) on drug-resistant Candida vaginal isolates. Method: Therefore, the antimicrobial effect of tea tree, niaouli, white thyme, and cajeput EOs on the planktonic growth of Candida isolates was initially evaluated by an agar disc diffusion method. Then, the vapor-phase effect of tea tree EO (VP-TTEO) on biofilm formation and on pre-formed biofilms was evaluated by crystal violet staining, XTT reduction assay, colony forming units’ enumeration, and scanning electron microscopy. Results: The results revealed high antifungal activity of EOs against drug-resistant Candida isolates. Additionally, the VP-TTEO showed a significant inhibitory effect on the biofilm formation of all tested isolates and was able to provoke an expressive reduction in mature Candida albicans biofilms. Conclusions: Overall, this study suggests that the VP-EO may be a promising solution that is able to prevent biofilm-related VVC caused by antifungal-resistant strains.

Passive UHF RFID Voice Prosthesis Mounted Sensor for Microbial Growth Detection

Capacitive loading due to human tissue can lead to low efficiency for implantable Passive Radio Frequency Identification (RFID) antennas. The presented passive UHF antenna sensor provides read distances above 0.5 meters (within a body phantom) by utilizing a convoluted half-wave dipole design. It is able to detect simulated early to mature Candida albicans biofilm growth when mounted upon a voice prosthesis (up to a $30~\mu \text{m}$ biofilm thickness). Depending on the propagation frequency of interest, as early 4-hour growth (5 to $10~\mu \text{m}$ biofilm thickness) equivalent could be detected and before any device failure could occur due to the colonization. This was accomplished by utilising thin layers of polyurethane to decouple the saliva from the presented UHF sensor (biofilm growth is known to increase layer hydrophobicity). This presented sensor has better functionality within the U.S. UHF frequency band as it detects changes above $5~\mu \text{m}$ . If there is a need for implantation within additional tissues with variable dielectric properties, a shunt capacitance of 2.6 pF could allow the system functionality within the permittivity range of 21 to 58. Allowing for immediate medical intervention before medical prosthesis failure.

An Evaluation of Norspermidine on Anti-fungal Effect on Mature Candida albicans Biofilms and Angiogenesis Potential of Dental Pulp Stem Cells.

Norspermidine (Nspd) is a kind of polyamine molecule, which is common in eukaryotes and prokaryotes. It has been reported as a potential anti-biofilms agent of bacteria, but its anti-fungal effect remains unclear. Candida albicans (C. albicans) is a common opportunistic pathogen in oral cavity of human beings. C. albicans biofilm is often seen in dental caries. In this work, we aimed to study the effect of Nspd on mature Candida albicans biofilms and to investigate how Nspd would influence human dental pulp stem cells (DPSCs). Our biofilm assays indicated that 111.7 and 55.9 mM Nspd dispersed 48 h mature fungal biofilms and showed significant fungicidal effect. 27.9 and 14.0 mM Nspd showed moderate fungicidal effect. Live/dead staining echoed the fungicidal effect. 111.7–14.0 mM Nspd showed a dose- inhibitory effect on mature fungal biofilm, where 14.0 mM Nspd reduced the metabolic activity by half compared with blank control. Moreover, we demonstrated that 111.7–27.9 mM Nspd restrained the production of hyphae form of C. albicans via SEM. Low dose Nspd (27.9 and 14.0 mM) could significantly reduce virulence related gene expression in C. albicans biofilms. MTT assay displayed a dose effect relation between 2.5–0.08 mM Nspd and DPSCs viability, where 0.63 mM Nspd reduced the viable level of DPSCs to 75% compared with blank control. Live/dead staining of DPSCs did not show distinctive difference between 0.63 mM Nspd and blank control. Vascular differentiation assay showed capillary-like structure of inducted DPSCs culture with and without 0.63 mM Nspd suggesting that it did not significantly affect angiogenic differentiation of DPSCs. Nspd can penetrate remaining dentin at low level, which is confirmed by an in vitro caries model. In conclusion, our study indicated high dosage Nspd (111.7 and 55.9 mM) could effectively disrupt and kill mature fungal biofilms. Low dosage (27.9 and 14.0 mM) showed mild anti-fungal effect on mature C. albicans biofilms. Human DPSCs were tolerate to 0.08–0.63 mM Nspd, where viability was over 75%. 0.63 mM Nspd did not affect the proliferation and angiogenetic differentiation of DPSCs.

Antimicrobial Activity of Different Artemisia Essential Oil Formulations.

The extreme lipophilicity of essential oils (EOs) impedes the measurement of their biological actions in an aqueous environment. We formulated oil in water type Pickering Artemisia annua EO nanoemulsions (AEP) with surface-modified Stöber silica nanoparticles (20 nm) as the stabilizing agent. The antimicrobial activity of AEP and its effects on mature Candida biofilms were compared with those of Tween 80 stabilized emulsion (AET) and ethanolic solution (AEE) of the Artemisia EO. The antimicrobial activity was evaluated by using the minimum inhibitory concentrations (MIC90) and minimum effective concentrations (MEC10) of the compounds. On planktonic bacterial and fungal cells beside growth inhibition, colony formation (CFU/mL), metabolic activity, viability, intracellular ATP/total protein (ATP/TP), along with reactive oxygen species (ROS) were also studied. Artemisia annua EO nanoemulsion (AEP) showed significantly higher antimicrobial activity than AET and AEE. Artemisia annua EO nanoemulsions (AEP) generated superoxide anion and peroxides-related oxidative stress, which might be the underlying mode of action of the Artemisia EO. Unilamellar liposomes, as a cellular model, were used to examine the delivery efficacy of the EO of our tested formulations. We could demonstrate higher effectiveness of AEP in the EO components’ donation compared to AET and AEE. Our data suggest the superiority of the AEP formulation against microbial infections.

Oxadiazolylthiazoles as novel and selective antifungal agents

Studying the structure-activity relationships (SAR) of oxadiazolylthiazole antibiotics unexpectedly led us to identify ethylenediamine- and propylenediamine-analogs as potential antimycotic novel lead structures. Replacement of the ethylenediamine moiety for the lead compound 7 with cis-diaminocyclohexyl group (compound 18) significantly enhanced the antifungal activity. In addition to the high safety margin of 18 against mammalian cells, it showed highly selective broad-spectrum activity against fungal cells without inhibiting the human normal microbiota. The antifungal activity of 18 was investigated against 20 drug-resistant clinically important fungi, including Candida species, Cryptococcus, and Aspergillus fumigatus strains. In addition to the low MIC values that mostly ranged between 0.125 and 2.0 μg/mL, compound 18 outperformed fluconazole in disrupting mature Candida biofilm.

Marine bacterial DNase curtails virulence and disrupts biofilms of Candida albicans and non-albicans Candida species

Candida is one of the most prevalent fungal pathogens in clinical settings which form antibiotic-resistant biofilms on biomedical devices. Hence, there is a need for non-antimicrobial alternatives to combat these infections. The present study investigates the anti-biofilm effect of marine bacterial DNase by targeting the eDNA present in the biofilms of Candida spp. A strain of Vibrio alginolyticus (AMSII) which showed enhanced DNase activity was isolated from marine sediment. Treatment of young and mature Candida biofilms with purified marine bacterial DNase (MBD) caused a 60-80% reduction in biofilm biomass, similar to treatment with DNase I from Bovine pancreas. Scanning electron microscopy showed that MBD significantly reduced the formation of biofilms on urinary catheters and more importantly prevented the virulent yeast to hyphae dimorphic switch in C. albicans. The present study identified a potential non-antibiotic alternative therapy to eradicate Candida biofilms and can be used to develop enzyme fabricated antifouling indwelling medical devices.

CD101, a Novel Echinocandin, Possesses Potent Antibiofilm Activity against Early and Mature Candida albicans Biofilms.

ABSTRACTCurrently available echinocandins are generally effective against Candida biofilms, but the recent emergence of resistance has underscored the importance of developing new antifungal agents that are effective against biofilms. CD101 is a long-acting novel echinocandin with distinctive pharmacokinetic properties and improved stability and safety relative to other drugs in the same class. CD101 is currently being evaluated as a once-weekly intravenous (i.v.) infusion for the treatment of candidemia and invasive candidiasis. In this study, we determined (i) the effect of CD101 against early and mature phase biofilms formed by C. albicans in vitro and (ii) the temporal effect of CD101 on the formation of biofilms using time-lapse microscopy (TLM). Early- or mature-phase biofilms were formed on silicone elastomer discs and were exposed to the test compounds for 24 h and quantified by measuring their metabolic activity. Separate batches were observed under a confocal microscope or used to capture TLM images from 0 to 16 h. Measurements of their metabolic activity showed that CD101 (0.25 or 1 μg/ml) significantly prevented adhesion-phase cells from developing into mature biofilms (P = 0.0062 or 0.0064, respectively) and eradicated preformed mature biofilms (P = 0.04 or 0.01, respectively) compared to those of untreated controls. Confocal microscopy showed significant reductions in biofilm thicknesses for both early and mature phases (P < 0.05). TLM showed that CD101 stopped the growth of adhesion- and early-phase biofilms within minutes. CD101-treated hyphae failed to grow into mature biofilms. These results suggest that CD101 may be effective in the prevention and treatment of biofilm-associated nosocomial infections.

Herpes simplex virus-1 entrapped in Candida albicans biofilm displays decreased sensitivity to antivirals and UVA1 laser treatment

BackgroundRecently, we published data suggesting a mutualistic relationship between HSV-1 and Candida. albicans; in particular: (a) HSV-1 infected macrophages are inhibited in their anti-Candida effector function and (b) Candida biofilm protects HSV-1 from inactivation. The present in vitro study is aimed at testing the effects of Candida biofilm on HSV-1 sensitivity to pharmacological and physical stress, such as antiviral drugs (acyclovir and foscarnet) and laser UVA1 irradiation. We also investigated whether fungus growth pattern, either sessile or planktonic, influences HSV-1 sensitivity to antivirals.MethodsMature Candida biofilms were exposed to HSV-1 and then irradiated with laser light (UVA1, 355 λ). In another set of experiments, mature Candida biofilm were co-cultured with HSV-1 infected VERO cells in the presence of different concentrations of acyclovir or foscarnet. In both protocols, controls unexposed to laser or drugs were included. The viral yield of treated and untreated samples was evaluated by end-point titration. To evaluate whether this protective effect might occur in relation with a different growth pattern, HSV-1 infected cells were co-cultured with either sessile or planktonic forms of Candida and then assessed for susceptibility to antiviral drugs.ResultsUVA1 irradiation caused a 2 Log reduction of virus yield in the control cultures whereas the reduction was only 1 Log with Candida biofilm, regardless to the laser dose applied to the experimental samples (50 or 100 J/cm2). The presence of biofilm increased the IC90 from 18.4–25.6 J/cm2. Acyclovir caused a 2.3 Log reduction of virus yield in the control cultures whereas with Candida biofilm the reduction was only 0.5 Log; foscarnet determined a reduction of 1.4 Log in the controls and 0.2 Log in biofilm cultures. Consequently, the ICs50 for acyclovir and foscarnet increased by 4- and 12-folds, respectively, compared to controls. When HSV-1 was exposed to either sessile or planktonic fungal cells, the antiviral treatments caused approximately the same weak reduction of virus yield.ConclusionsThese data demonstrate that: (1) HSV-1 encompassed in Candida biofilm is protected from inactivation by physical (laser) and pharmacological (acyclovir or foscarnet) treatments; (2) the drug antiviral activity is reduced at a similar extent for both sessile or planktonic Candida.

Synthesis of Cyclic Imides (Methylphtalimides, Carboxylic Acid Phtalimides and Itaconimides) and Evaluation of their Antifungal Potential.

This paper describes the synthesis of three different subfamilies of cyclic imides: methylphtalimides, carboxyl acid phtalimides and itaconimides. Fifteen compounds (five of each sub-family) were obtained by the reaction of appropriated anhydrides and different aromatic amines, using the manual Topliss method. Their structures were confirmed by spectral data (IR and NMR). The antifungal activity of the synthesized compounds was investigated by broth microdilution to determine the minimal inhibitory concentration (MIC). The ability to inhibit the biofilm formation or destroy mature Candida albicans biofilm was also evaluated for the most active substances. The results indicated that only the itaconimides 11-15 exhibited potent and promising antifungal properties, with MIC100 between 1 and 64 μg mL-1, being several times more potent than the reference drug, Fluconazole. Compounds 11-15 inhibited between 64% and 95% of biofilm formation, and destroyed between 78% and 99% of mature biofilm at a concentration of 64 μg mL-1. ADME (absorption, distribution, metabolism and excretion) in silico evaluations were carried out to predict whether the molecules under study are good drug candidates. Itaconimides appear to be promising and relevant as tools for the future development of new and effective medicinal agents to treat fungal diseases.

Chemical composition and antifungal potential of Brazilian propolis against Candida spp.

Propolis is known to have biological properties against numerous microorganisms of clinical interest. This study aimed to determine the chemical composition and antifungal activity of Brazilian propolis (types 3 and 13) against Candida spp. and their effects on the morphology of preformed and mature Candida biofilms. Samples of propolis (3 and 13) collected by Apis mellifera honeybees were obtained from different regions in Brazil. Ethanolic extracts of propolis (EEP) were prepared, fractionated and submitted to chemical analysis by GC/MS. The extracts and their hexane, dichloromethane and ethyl acetate fractions were tested for their ability to inhibit Candida spp. (C.albicans, C.dubliniensis, C.glabrata, C.kruzei, C.tropicalis and C.parapsilosis) by determination of the minimum inhibitory and fungicidal concentrations (MIC/MFC). Additionally, their effects on morphology of preformed and mature biofilms were observed by scanning electron microscopy. The phenolic compounds p-coumaric acid, caffeic acid phenethyl ester (CAPE), kaempferol and quercetin were identified in the EEP-3 and its bioactive dichloromethane fraction; and isoflavonoids such as medicarpin, vestitol and formononetin were found in the EEP-13, and triterpenes in its bioactive hexane fraction. The EEP-3 and EEP-13 and their bioactive fractions showed MIC values ranging from 0.2 to 125μg/mL and MFC values between 125 and 500μg/mL. The EEP and fractions were predominantly fungistatic agents. All extracts and fractions disrupted biofilm structures at 500μg/mL and amorphous areas with cell damage were clearly observed in preformed and mature biofilms. Propolis types 3 and 13 have strong anti-Candida activity and should be considered as promising candidates to treat oral and systemic candidiasis.

New pharmacological properties of Medicago sativa and Saponaria officinalis saponin-rich fractions addressed to Candida albicans

The antifungal activity of the saponin-rich fractions (SFs) from Medicago sativa (aerial parts and roots) and Saponaria officinalis (used as a well-known source of plant saponins) against Candida albicans reference and clinical strains, their yeast-to-hyphal conversion, adhesion, and biofilm formation was investigated. Direct fungicidal/fungistatic properties of the tested phytochemicals used alone, as well as their synergy with azoles (probably resulting from yeast cell wall instability) were demonstrated. Here, to the best of our knowledge, we report for the first time the ability of saponin-rich extracts of M. sativa and S. officinalis to inhibit C. albicans germ tube formation, limit hyphal growth, reduce yeast adherence and biofilm formation, and eradicate mature (24 h) Candida biofilm. Moreover, M. sativa SFs (mainly obtained from aerial parts), in the range of concentrations which were active modulators of Candida virulence factors, exhibited low cytotoxicity against the mouse fibroblast line L929. These properties seem to be very promising in the context of using plant-derived SFs as potential novel antifungal therapeutics supporting classic drugs or as ingredients of disinfectants.

Silver colloidal nanoparticle stability: influence on Candida biofilms formed on denture acrylic.

Our aim in this study was to evaluate how the chemical stability of silver nanoparticles (SNs) influences their efficacy against Candida albicans and C. glabrata biofilms. Several parameters of SN stability were tested, namely, temperature (50ºC, 70ºC, and 100ºC), pH (5.0 and 9.0), and time of contact (5 h and 24 h) with biofilms. The control was defined as SNs without temperature treatment, pH 7, and 24 h of contact. These colloidal suspensions at 54 mg/L were used to treat mature Candida biofilms (48 h) formed on acrylic. Their efficacy was determined by total biomass and colony-forming unit quantification. Data were analyzed using analysis of variance and the Bonferroni post hoc test (α = 0.05). The temperature and pH variations of SNs did not affect their efficacy against the viable cells of Candida biofilms (P > 0.05). Moreover, the treatment periods were not decisive in terms of the susceptibility of Candida biofilms to SNs. These findings provide an important advantage of SNs that may be useful in the treatment of Candida-associated denture stomatitis.

In Vitro Effect of Amphotericin B on Candida albicans, Candida glabrata and Candida parapsilosis Biofilm Formation

Candida spp. biofilm is considered highly resistant to conventional antifungals. The aim of this study was to investigate the in vitro effect of amphotericin B on Candida spp. biofilms at different stages of maturation. We investigated the activity of amphotericin B against 78 clinical isolates of Candida spp., representing three species, growing as planktonic and sessile cells, by a widely accepted broth microdilution method. The in vitro effect on sessile cell viability was evaluated by MTT reduction assay. All examined strains were susceptible to amphotericin B when grown as free-living cells. At the early stages of biofilm maturation 96.7-100.0 % strains, depending on species, displayed amphotericin B sessile minimal inhibitory concentration (SMIC) ≤ 1 μg/mL. Mature Candida spp. biofilm of 32.1-90.0 % strains displayed amphotericin B SMIC ≤ 1 μg/mL. Based on these results, amphotericin B displays species- and strain-depending activity against Candida spp. biofilms.

Antifungal activity of silver nanoparticles in combination with nystatin and chlorhexidine digluconate against Candida albicans and Candida glabrata biofilms

Although silver nanoparticles (SN) have been investigated as an alternative to conventional antifungal drugs in the control of Candida-associated denture stomatitis, the antifungal activity of SN in combination with antifungal drugs against Candida biofilms remains unknown. Therefore, the aim of this study was to evaluate the antifungal efficacy of SN in combination with nystatin (NYT) or chlorhexidine digluconate (CHG) against Candida albicans and Candida glabrata biofilms. The drugs alone or combined with SN were applied on mature Candida biofilms (48 h), and after 24 h of treatment their antibiofilm activities were assessed by total biomass quantification (by crystal violet staining) and colony forming units enumeration. The structure of Candida biofilms was analysed by scanning electron microscopy (SEM) images. The data indicated that SN combined with either NYT or CHG demonstrated synergistic antibiofilm activity, and this activity was dependent on the species and on the drug concentrations used. SEM images showed that some drug combinations were able to disrupt Candida biofilms. The results of this study suggest that the combination of SN with NYT or CHG may have clinical implications in the treatment of denture stomatitis. However, further studies are needed before recommending the use of these drugs safely in clinical situations.

Activities of Systemically Administered Echinocandins against In Vivo Mature Candida albicans Biofilms Developed in a Rat Subcutaneous Model

This study addresses the effects of micafungin, caspofungin, and anidulafungin against Candida albicans biofilms developed in a subcutaneous catheter rat model system. Doses of 5, 10, and 30 mg/kg (of body weight)/day (the last only for micafungin) were given intravenously for 5, 7, and 10 days. All three echinocandins caused a significant reduction of the Candida cell numbers on the implanted catheters and are thus promising for the treatment of biofilm-related infections.