Evaluation of Candida albicans adhesion and biofilm formation on a denture base acrylic resin containing silver nanoparticles

Aim: This study firstly evaluated the activity of a silver nanoparticle (AgNPs) solution against Candida albicans and then the effect of incorporation of AgNPs into a denture base acrylic resin on the material’s hydrophobicity, C. albicans adhesion and biofilm formation. Methods and Results: The AgNPs solution was synthesized by chemical reduction and characterized. Minimum inhibitory (MIC) and minimum fungicidal (MFC) concentrations for planktonic cells and sessile cells (MFCs) of the AgNPs solution against C. albicans were determined. Specimens (n = 360) of silver‐incorporated acrylic resin at concentrations of 1000, 750, 500, 250 and 30 ppm were also prepared and stored in PBS for 0, 7, 90 and 180 days. Control was acrylic resin without AgNPs (0 ppm). After the storage periods, contact angles were measured and the specimens were used for C. albicans adherence (37°C; 90 min; n = 9) and biofilm formation (37°C; 48 h; n = 9) by XTT reduction assay. MIC, MFC and MFCs values were 3·98, 15·63 and 1000 ppm, respectively. Incorporation of AgNPs reduced the hydrophobicity of the resin. No effect on adherence and biofilm formation was observed. At 90 and 180 days of storage, there was significant increase in adherence and biofilm formation. Conclusions: Although the AgNPs solution had antifungal activity, no effect on C. albicans adherence and biofilm formation was observed after its incorporation into a denture base resin. Significance and Impact of the Study: The synthesized AgNPs solution is a promising antifungal agent, warranting investigations of more efficient methods of incorporation into denture base resins.     

Efficacy of surface-generated nitric oxide against Candida albicans adhesion and biofilm formation

This report details the efficacy of nitric oxide (NO)-releasing xerogel surfaces composed of N-(6-aminohexyl)aminopropyl trimethoxysilane (AHAP3) and isobutyltrimethoxysilane (BTMOS) against Candida albicans adhesion, viability, and biofilm formation. A parallel plate flow cell assay was used to examine the effect of NO on planktonic fungal cells. Nitric oxide fluxes as low as 14 pmol cm^?2 s^?1 were sufficient to reduce fungal adhesion by ～49% over the controls after 90 min. By utilizing a fluorescence live/dead assay and replicate plating, NO flux was determined to reduce fungal viability in a dose-dependent manner. The formation of C. albicans biofilms on NO-releasing xerogel-coated silicon rubber (SiR) coupons was impeded when compared to control (non-NO-releasing) and bare SiR surfaces. The synergistic efficacy of NO and silver sulfadiazine against adhered fungal cells and biofilms is reported with increased killing and biofilm inhibition over NO alone.     

The antagonistic effect of Saccharomyces boulardii on Candida albicans filamentation, adhesion and biofilm formation

The dimorphic fungus Candida albicans is a member of the normal flora residing in the intestinal tract of humans. In spite of this, under certain conditions it can induce both superficial and serious systemic diseases, as well as be the cause of gastrointestinal infections. Saccharomyces boulardii is a yeast strain that has been shown to have applications in the prevention and treatment of intestinal infections caused by bacterial pathogens. The purpose of this study was to determine whether S. boulardii affects the virulence factors of C. albicans . We demonstrate the inhibitory effect of live S. boulardii cells on the filamentation (hyphae and pseudohyphae formation) of C. albicans SC5314 strain proportional to the amount of S. boulardii added. An extract from S. boulardii culture has a similar effect. Live S. boulardii and the extract from S. boulardii culture filtrate diminish C. albicans adhesion to and subsequent biofilm formation on polystyrene surfaces under both aerobic and microaerophilic conditions. This effect is very strong and requires lower doses of S. boulardii cells or concentrations of the extract than serum-induced filamentation tests. Saccharomyces boulardii has a strong negative effect on very important virulence factors of C. albicans , i.e. the ability to form filaments and to adhere and form biofilms on plastic surfaces.     

Candida albicans biofilm formation on soft denture liners and efficacy of cleaning protocols

doi: 10.1111/j.1741‐2358.2011.00485.x
Candida albicans biofilm formation on soft denture liners and efficacy of cleaning protocols Objective: The aim of this study was to investigate Candida albicans biofilm formation on denture liners and to analyse the efficacy of cleaning protocols. Material and methods: Specimens were prepared from four silicone‐based soft denture liners. After artificial ageing and surface free energy determination, specimens were incubated with saliva (2 h) and Candida albicans ATCC 10231 for either short‐ (2.5 h) or long‐term (24 h) biofilm formation. Adherent cells were determined either after incubation of specimens with Candida albicans or after treatment with different denture cleaning protocols. Statistical analysis was performed using one‐way anova and the Games–Howell test (α = 0.05). Results: For both short‐ and long‐term biofilm formation, similar amounts of Candida albicans cells were found on the surface of the different liners (p = 0.295 and 0.178, respectively). For both short‐ and long‐term biofilm formation, the highest cleaning efficacy was observed for sodium hypochlorite (NaOCl; p < 0.01). The efficacy of the chemical denture cleaner in removing long‐term Candida albicans biofilms was significantly lower than the efficacy of removal by brushing (p < 0.001). Conclusion: Different silicone‐based soft denture liners yield similar Candida albicans biofilm formation on their surface. The highest efficacy for the removal of Candida albicans biofilms was identified for NaOCl. Chemical denture cleaners appear to have rather low efficacy to remove mature Candida albicans biofilms.     

CRK1基因缺失对白念珠菌形态、黏附、生物被膜的影响

目的 研究CRK1基因缺失对白念珠菌形态、黏附、生物被膜的影响.方法 显微镜下观察,计算菌丝形成率,比较CRK1基因缺失菌（Δcrk1菌）及标准菌SC5314形成菌丝的能力;建立肠黏膜模型,计算黏附率,评价CRK1基因缺失对白念珠菌黏附的影响;MTT法及结晶紫法（CV）评价CRK1基因缺失对白念珠菌生物被膜形成的影响.结果 与SC5314相比,Δcrk1菌分别在10％胎牛血清和RPMI-1640培养条件下形成菌丝能力均较弱,两者之间有统计学差异;Δcrk1菌在60、90、120 min时对肠黏膜的黏附数明显少于标准菌SC5314,两者之间有统计学差异;通过MTT法、结晶紫法两种方法证实了,在经48 h培养后,Δcrk1菌与其标准菌SC5314相比,形成生物膜的能力弱,两者之间差异有统计学差异.结论 CRK 1基因缺失影响白念珠菌菌丝二态性的转化,进而影响黏附力和生物被膜的形成.     

抗白念珠菌生物被膜药物的研究进展

白念珠菌是临床最常见的一种能产生生物被膜的致病真菌,所产生的生物被膜是导致高度耐药性和临床白念珠菌反复感染的直接原因.近年来,科学家们开始关注天然产物的抗生物被膜活性,以及不同药物联合应用的抗生物被膜效果,该文对抗白念珠菌生物被膜药物的研究进展作一综述.     

Candida albicans biofilm formation on peptide functionalized polydimethylsiloxane

In order to prevent biofilm formation by Candida albicans, several cationic peptides were covalently bound to polydimethylsiloxane (PDMS). The salivary peptide histatin 5 and two synthetic variants (Dhvar 4 and Dhvar 5) were used to prepare peptide functionalized PDMS using 4-azido-2,3,5,6-tetrafluoro-benzoic acid (AFB) as an interlinkage molecule. In addition, polylysine-, polyarginine-, and polyhistidine-PDMS surfaces were prepared. Dhvar 4 functionalized PDMS yielded the highest reduction of the number of C. albicans biofilm cells in the Modified Robbins Device. Amino acid analysis demonstrated that the amount of peptide immobilized on the modified disks was in the nanomole range. Poly-d-lysine PDMS, in particular the homopeptides with low molecular weight (2500 and 9600) showed the highest activity against C. albicans biofilms, with reductions of 93% and 91%, respectively. The results indicate that the reductions are peptide dependent.     

大蒜素对白色念珠菌生物被膜形成的作用

生物被膜的形成是白色念珠菌产生耐药性的重要原因之一。本研究首先构建白色念珠菌体外生物被膜模型,通过倒置显微镜和甲基四氮盐（XTT）法检测大蒜素对白色念珠菌生物被膜形成的影响,同时采用实时荧光定量PCR法（qRT-PCR）对白色念珠菌生物被膜相关基因ALS1、ALS3、HWP1、MP65、SUN41的表达水平进行检测。结果显示,当大蒜素浓度≥12.5μg/mL时,白色念珠菌生物被膜的生长被抑制,并且在生物被膜形成的早期,大蒜素干预能有效抑制其形成;大蒜素能下调白色念珠菌生物被膜相关基因ALS1、ALS3、HWP1、MP65、SUN41的表达水平。研究结果提示,大蒜素可有效抑制体外白色念珠菌生物被膜的形成,可能与其下调生物被膜相关基因的表达有关。     

白念珠菌生物被膜形成的遗传调控机制

白念珠菌是人体重要的条件性致病真菌。形态的多样性和可塑性是白念珠菌典型的生物学特征,这与它的致病性、宿主适应能力以及有性生殖过程密切相关。白念珠菌生物被膜(Biofilm)是由不同形态细胞(包括酵母型、菌丝和假菌丝)以及胞外基质组成的致密结构,也是毒性和耐药性形成的重要因子。生物被膜对抗真菌药物、宿主免疫系统和环境胁迫因子等都表现出较强的抵抗力和耐受性,是临床上病原真菌感染防治的重大挑战。随着基因表达谱和遗传操作技术的发展,白念珠菌生物被膜的形成及其耐药性的获得所依赖的遗传调控通路和分子调控机制越来越清楚。主要包括MAPK和cAMP介导的信号途径以及Bcr1和Tec1等因子介导的转录调控。此外,白念珠菌生物被膜的形成与形态转换和有性生殖之间存在密切的联系。文中综述了白念珠菌生物被膜形成的遗传调控机制,重点介绍了细胞壁相关蛋白、转录因子和交配型对该过程的调控以及生物被膜的耐药机制。     

胶体纳米银对白假丝酵母菌的抑制作用

目的 探讨胶体纳米银对白假丝酵母菌的抑制作用。方法 以白假丝酵母菌为研究对象,采用倍比稀释及涂布法,检测胶体纳米银对白假丝酵母菌的抑制作用及影响因素。结果 化学纳米银及物理纳米银对白假丝酵母菌的最小抑菌浓度及最小杀菌浓度相同,分别为3.13 μg/mL和6.25 μg/mL。12.50 μg/mL的化学纳米银及物理纳米银可在5 min内完全杀死白假丝酵母菌。胶体纳米银的抑菌作用受到杀菌环境的影响,特别氯离子对胶体纳米银的杀菌作用有明显的影响。结论 胶体纳米银对白假丝酵母菌具有明显的抑菌作用,其抑制作用易受到氯离子及蛋白质的的影响。