Antifungal Susceptibility and Candida sp. Biofilm Production in Clinical Isolates of HIV-Positive Brazilian Patients under HAART Therapy.

The aim of the present study was to characterize biofilms formed by Candida spp. clinical isolates (n = 19), isolated from the oral mucosa of HIV-positive patients. For characterizing the biofilms formed by several Candida sp. strains, isolated from HIV-positive patients, in terms of formed biomass, matrix composition and antifungal susceptibility profile, clinical isolates (n = 19) were collected from oral mucosa and identified. The biofilm of the samples was cultured with fluconazole (1250 mg/L), voriconazole (800 mg/L), anidulafungin (2 mg/L) or amphotericin B (2 mg/L). Afterwards, the quantification of the total biomass was performed using crystal violet assay, while the proteins and carbohydrates levels were quantified in the matrix. The results showed a predominance of C. albicans, followed by C. krusei. Around 58% of the Candida spp. biofilm had susceptibility to fluconazole and voriconazole (800 mg/L), 53% to anidulafungin and 74% to amphotericin B. C. krusei presented both the lowest and the highest biofilm matrix contents in polysaccharides and proteins. The low resistance to antifungal agents reported here was probably due to the fact that none of the participants had a prolonged exposure to these antifungals. A predominance of less virulent Candida spp. strains with low or no resistance to antifungals was observed. This can be attributed to a low fungal selective pressure. This most probably happened due to a low fungal selective pressure but also due to a good adherence to HAART therapy, which guarantees a stable and stronger immune patient response.

Biomaterials with antifungal strategies to fight oral infections.

Oral fungal infections pose a threat to human health and increase the economic burden of oral diseases by prolonging and complicating treatment. A cost-effective strategy is to try to prevent these infections from happening in the first place. With this purpose, biomaterials with antifungal properties are a crucial element to overcome fungal infections in the oral cavity. In this review, we go through different kinds of biomaterials and coatings that can be used to functionalize them. We also review their potential as a therapeutic approach in addition to prophylaxis, by going through traditional and alternative antifungal compounds, e.g., essential oils, that could be incorporated in them, to enhance their efficacy against fungal pathogens. We aim to highlight the potential of these technologies and propose questions that need to be addressed in prospective research. Finally, we intend to concatenate the key aspects and technologies on the use of biomaterials in oral health, to create an easy to find summary of the current state-of-the-art for researchers in the field.

Characterization of Oral Candida spp. Biofilms in Children and Adults Carriers from Eastern Europe and South America.

BACKGROUND: Candida albicans and non-Candida albicans Candida species (NCACs) are known to colonize and invade various tissues, including the oral mucosa. In this work, we aimed to characterize mature biofilms of several Candida spp. clinical isolates (n = 33) obtained from the oral mucosa of children, adults, and elders of Eastern Europe and South America. METHODS: Each strain was evaluated for its capacity to form biofilms in terms of total biomass using the crystal violet assay and for matrix components production (proteins and carbohydrates) using the BCA and phenol-sulfuric tests, respectively. The effect of different antifungals on biofilm formation was studied. RESULTS: in the children's group, a predominance of C. krusei (81%) was observed, while, among adults, the main species was C. albicans (59%). Most strains showed a reduced response to antimicrobial drugs when in biofilm form (p < 0.01). Moreover, it was observed that strains isolated from children produced more matrix, with higher levels of protein and polysaccharides. CONCLUSIONS: children were more likely to be infected by NCACs than adults. More importantly, these NCACs were able to form biofilms richer in matrix components. This finding is of clinical importance, particularly in pediatric care, since stronger biofilms are highly associated with antimicrobial resistance, recurrent infections, and higher therapeutic failure.

Role of the Dietary Phytochemical Curcumin in Targeting Cancer Cell Signalling Pathways.

The diarylheptanoid curcumin [(1E,6E)-1,7-bis(4-hydroxy-3-methoxyphenyl)hepta-1,6-diene-3,5-dione] is one of the phenolic pigments responsible for the yellow colour of turmeric (Curcuma longa L.). This phytochemical has gained much attention in recent years due to its therapeutic potential in cancer. A range of drug delivery approaches have been developed to optimise the pharmacokinetic profile of curcumin and ensure that it reaches its target sites. Curcumin exhibits numerous biological effects, including anti-inflammatory, cardioprotective, antidiabetic, and anti-aging activities. It has also been extensively studied for its role as a cancer chemopreventive and anticancer agent. This review focusses on the role of curcumin in targeting the cell signalling pathways involved in cancer, particularly via modulation of growth factors, transcription factors, kinases and other enzymes, pro-inflammatory cytokines, and pro-apoptotic and anti-apoptotic proteins. It is hoped that this study will help future work on the potential of curcumin to fight cancer.

Combination of Farnesol with Common Antifungal Drugs: Inhibitory Effect against Candida Species Isolated from Women with RVVC.

Background and Objectives: Vulvovaginal candidiasis (VVC) is a mucous membrane infection, with an increased rate of antifungal resistance of Candida species. In this study, the in vitro efficacy of farnesol alone or in combination with traditional antifungals was assessed against resistant Candida strains recovered from women with VVC. Materials and Methods: Eighty Candida isolates were identified by multiplex polymerase chain reaction (PCR), and the antifungal susceptibility to amphotericin B (AMB), fluconazole (FLU), itraconazole (ITZ), voriconazole (VOR), clotrimazole (CTZ), and farnesol was tested by the standard microdilution method. The combinations of farnesol with each antifungal were calculated based on the fractional inhibitory concentration index (FICI). Result: Candida glabrata was the predominant species (48.75%) isolated from vaginal discharges, followed by C. albicans (43.75%), C. parapsilosis (3.75%), a mixed infection of C. albicans and C. glabrata (2.5%) and C. albicans and C. parapsilosis (1%). C. albicans and C. glabrata isolates had lower susceptibility to FLU (31.4% and 23.0%, respectively) and CTZ (37.1% and 33.3%, respectively). Importantly, there was "synergism" between farnesol-FLU and farnesol-ITZ against C. albicans and C. parapsilosis (FICI = 0.5 and 0.35, respectively), reverting the original azole-resistant profile. Conclusion: These findings indicate that farnesol can revert the resistance profile of azole by enhancing the activity of FLU and ITZ in resistant Candida isolates, which is a clinically promising result.

Thymoquinone Antifungal Activity against Candida glabrata Oral Isolates from Patients in Intensive Care Units-An In Vitro Study.

The number of Candida spp. infections and drug resistance are dramatically increasing worldwide, particularly among immunosuppressed patients, and it is urgent to find novel compounds with antifungal activity. In this work, the antifungal and antibiofilm activity of thymoquinone (TQ), a key bioactive constituent of black cumin seed Nigella sativa L., was evaluated against Candida glabrata, a WHO 'high-priority' pathogen. Then, its effect on the expression of C. glabrata EPA6 and EPA7 genes (related to biofilm adhesion and development, respectively) were analyzed. Swab samples were taken from the oral cavity of 90 hospitalized patients in ICU wards, transferred to sterile falcon tubes, and cultured on Sabouraud Dextrose Agar (SDA) and Chromagar Candida for presumptive identification. Next, a 21-plex PCR was carried out for the confirmation of species level. C. glabrata isolates underwent antifungal drug susceptibility testing against fluconazole (FLZ), itraconazole (ITZ), amphotericin B (AMB), and TQ according to the CLSI microdilution method (M27, A3/S4). Biofilm formation was measured by an MTT assay. EPA6 and EPA7 gene expression was assessed by real-time PCR. From the 90 swab samples, 40 isolates were identified as C. glabrata with the 21-plex PCR. Most isolates were resistant to FLZ (n = 29, 72.5%), whereas 12.5% and 5% were ITZ and AMB resistant, respectively. The minimum inhibitory concentration (MIC50) of TQ against C. glabrata was 50 µg/mL. Importantly, TQ significantly inhibited the biofilm formation of C. glabrata isolates, and EPA6 gene expression was reduced significantly at MIC50 concentration of TQ. TQ seems to have some antifungal, antibiofilm (adhesion) effect on C. glabrata isolates, showing that this plant secondary metabolite is a promising agent to overcome Candida infections, especially oral candidiasis.

Our current clinical understanding of Candida biofilms: where are we two decades on?

Clinically we have been aware of the concept of Candida biofilms for many decades, though perhaps without the formal designation. Just over 20 years ago the subject emerged on the back of progress made from the bacterial biofilms, and academic progress pace has continued to mirror the bacterial biofilm community, albeit at a decreased volume. It is apparent that Candida species have a considerable capacity to colonize surfaces and interfaces and form tenacious biofilm structures, either alone or in mixed species communities. From the oral cavity, to the respiratory and genitourinary tracts, wounds, or in and around a plethora of biomedical devices, the scope of these infections is vast. These are highly tolerant to antifungal therapies that has a measurable impact on clinical management. This review aims to provide a comprehensive overight of our current clinical understanding of where these biofilms cause infections, and we discuss existing and emerging antifungal therapies and strategies.

Overview on the Infections Related to Rare Candida Species.

Atypical Candida spp. infections are rising, mostly due to the increasing numbers of immunocompromised patients. The most common Candida spp. is still Candida albicans; however, in the last decades, there has been an increase in non-Candida albicans Candida species infections (e.g., Candida glabrata, Candida parapsilosis, and Candida tropicalis). Furthermore, in the last 10 years, the reports on uncommon yeasts, such as Candida lusitaniae, Candida intermedia, or Candida norvegensis, have also worryingly increased. This review summarizes the information, mostly related to the last decade, regarding the infections, diagnosis, treatment, and resistance of these uncommon Candida species. In general, there has been an increase in the number of articles associated with the incidence of these species. Additionally, in several cases, there was a suggestive antifungal resistance, particularly with azoles, which is troublesome for therapeutic success.

Marine Compounds with Anti-Candida sp. Activity: A Promised "Land" for New Antifungals.

Candida albicans is still the major yeast causing human fungal infections. Nevertheless, in the last decades, non-Candida albicans Candida species (NCACs) (e.g., Candida glabrata, Candida tropicalis, and Candida parapsilosis) have been increasingly linked to Candida sp. infections, mainly in immunocompromised and hospitalized patients. The escalade of antifungal resistance among Candida sp. demands broadly effective and cost-efficient therapeutic strategies to treat candidiasis. Marine environments have shown to be a rich source of a plethora of natural compounds with substantial antimicrobial bioactivities, even against resistant pathogens, such as Candida sp. This short review intends to briefly summarize the most recent marine compounds that have evidenced anti-Candida sp. activity. Here, we show that the number of compounds discovered in the last years with antifungal activity is growing. These drugs have a good potential to be used for the treatment of candidiasis, but disappointedly the reports have devoted a high focus on C. albicans, neglecting the NCACs, highlighting the need to perform outspreading studies in the near future.

Effects of fluconazole on Candida glabrata biofilms and its relationship with ABC transporter gene expression.

Candida glabrata has emerged as the second most prevalent fungal pathogen and its ability to form biofilms has been considered one of the most important virulence factors, since biofilms present a high tolerance to antifungal agents used in fungal infection treatment. The mechanisms of biofilm tolerance to antifungal agents remain poorly understood. Thus, the aim of this study was to evaluate the effects of fluconazole (FLU) on the formation and control of C. glabrata biofilms and its relation with the expression of genes encoding for ABC transporters, CDR1, SNQ2, and PDR1. For that, minimal inhibitory concentration values for seven C. glabrata strains were determined and the effect of FLU against C. glabrata biofilms was evaluated by total biomass quantification and viable cell enumeration. Matrices from biofilms were analyzed in terms of protein, carbohydrate and DNA content. ABC transporter gene expression was analyzed for quantitative real-time PCR. In addition to the high amounts of proteins and carbohydrates detected in the extracellular matrices in the presence of FLU, this work showed that the overexpression of efflux pumps is a possible mechanism of biofilm tolerance to FLU and this phenomenon alters the structure of C. glabrata biofilms by creating cell clusters.