Candida albicans forms biofilms on the vaginal mucosa

Current understanding of resistance and susceptibility to vulvovaginal candidiasis challenges existing paradigms of host defence against fungal infection. While abiotic biofilm formation has a clearly established role during systemic Candida infections, it is not known whether C. albicans forms biofilms on the vaginal mucosa and the possible role of biofilms in disease. In vivo and ex vivo murine vaginitis models were employed to examine biofilm formation by scanning electron and confocal microscopy. C. albicans strains included 3153A (lab strain), DAY185 (parental control strain), and mutants defective in morphogenesis and/or biofilm formation in vitro (efg1/efg1 and bcr1/bcr1). Both 3153A and DAY815 formed biofilms on the vaginal mucosa in vivo and ex vivo as indicated by high fungal burden and microscopic analysis demonstrating typical biofilm architecture and presence of extracellular matrix (ECM) co-localized with the presence of fungi. In contrast, efg1/efg1 and bcr1/bcr1 mutant strains exhibited weak or no biofilm formation/ECM production in both models compared to wild-type strains and complemented mutants despite comparable colonization levels. These data show for the first time that C. albicans forms biofilms in vivo on vaginal epithelium, and that in vivo biotic biofilm formation requires regulators of biofilm formation (BCR1) and morphogenesis (EFG1)

Antifungal resistance gene expressions in various lifestyles of Candida albicans

Oral Presentation: abstract no. 74Objectives: Lifestyle change of Candida albicans from planktonic to biofilm is one way of acquiring higher antifungal resistance. Therefore, the purpose of present study was to investigate the expressions of antifungal resistance genes in three growth modes, i.e. planktonic, adhesion and biofilm. Furthermore, we investigated the effect of ...link_to_OA_fulltextThe International Association for Dental Research (IADR) 88th General Session and Exhibition 2010, Barcelona, Spain, 14-17 July 2010

Shotgun Proteomics elucidates the regulatory pathway of Candida biofilms

Objectives: Biofilm formation and filamentation are major virulent attributes of the fungal pathogen Candida albicans. Mitogen Activated Proteins Kinase (MAPK) and cAMP/Protein Kinase (PKA) pathways are the two major biological pathways that regulate these attributes. Therefore, aim of the present study was to elucidate the role of MAPK, PKA pathways using Candida mutants lacking CPH1 and EFG1; major regulators of MAPK and PKA pathways, respectively. Methods: Initially, biofilm formation, anti-oxidative capacities and antifungal susceptibility of Candida mutants were studied using standard methodology. Thereafter, protein lysates of respective biofilms were quantified, denatured, and cysteines blocked. Each sample was then digested with trypsin and labeled with the iTRAQ tags. Differentially labeled digests were subjected to LC-MALDI-TOF/TOF analysis. The MS/MS peptides and phosphorylation patterns were identified by bioinformatics tools and further validated using Candida Genome Database (CGD). Results: The mutant lacking EFG1 was devoid of filaments and unable to form mature biofilms, and more susceptible to oxidative stress and antifungals, compared to the wild type strain. Totally, 861 proteins over 95% C.I. which are related to MAPK and PKA pathways were identified. In particular out of 452 known and characterized proteins, 133 related to PKA pathway were down-regulated more than two folds compared to 20 proteins down-regulated in MAPK pathway. Of these down-regulated proteins a considerable number was related to the stress response and drug resistance. Of the characterized proteins, 317 were phosphorylated and 24 were fungal specific. Further, 409 yet uncharacterized proteins were also identified. . Conclusion: cAMP/PKA pathway, but not MAPK pathway governs the filamentation and biofilm formation of Candida albicans. PKA related stress response proteins may potentially mediate the higher antifungal resistance seen in Candida biofilms. Fungal specific, PKA pathway biomarkers, and their phosphorylation profiles are likely to be of use in the search for the novel antifungals. (RGC-Grant HKU-7624/06M

Susceptibility of Candida albicans filamentation-defective mutants to clinical biocides

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Preparation of Ag-containing diamond-like carbon films on the interior surface of tubes by a combined method of plasma source ion implantation and DC sputtering

Adhesive diamond-like carbon (DLC) films can be prepared by plasma source ion implantation (PSII), which is also suitable for the treatment of the inner surface of a tube. Incorporation of a metal into the DLC film provides a possibility to change the characteristics of the DLC film. One source for the metal is DC sputtering. In this study PSII and DC sputtering were combined to prepare DLC films containing low concentrations of Ag on the interior surfaces of stainless steel tubes. A DLC film was deposited using a C2H4 plasma with the help of an auxiliary electrode inside of the tube. This electrode was then used as a target for the DC sputtering. A mixture of the gases Ar and C2H4 was used to sputter the silver. By changing the gas flow ratios and process time, the resulting Ag content of the films could be varied. Sample characterizations were performed by X-ray photoelectron spectroscopy, secondary ion mass spectrometry, atomic force microscopy and Raman spectroscopy. Additionally, a ball-on-disk test was performed to investigate the tribological properties of the films. The antibacterial activity was determined using Staphylococcus aureus bacteria. (C) 2014 Elsevier B.V. All rights reserved

Effect of filamentation and mode of growth on antifungal susceptibility of Candida albicans

Biofilm formation involving profuse hyphal growth is a major characteristic of Candida spp. and confers higher antifungal resistance than its planktonic mode of growth. We investigated the antifungal susceptibility of Candida albicans and its hyphal mutants (Δefg1/efg1, Δcph1/cph1 and ΔΔcph1/cph1 efg1/efg1) to commonly used antifungals during planktonic, adhesion and biofilm modes of growth. The minimum inhibitory concentration (MIC) of each antifungal agent was determined for a lower inoculum (1 × 10 3 cells/mL) and higher inoculum (1 × 10 7 cells/mL) of planktonic Candida. Furthermore, MICs of C. albicans biofilms and adhesion modes of growth were determined with a standard XTT assay. Candida albicans in adhesion and biofilm modes of growth, but not in planktonic mode, were resistant to all five antifungal agents tested. Although Δefg1/efg1 and ΔΔcph1/cph1 efg1/efg1 mutants formed less biofilm than wild-type C. albicans SC5314, they were similarly resistant to caspofungin. However, these mutants were more sensitive to amphotericin B and nystatin than the wild-type. Adhesion per se confers increased resistance to antifungal agents, which is further pronounced in the biofilm mode of Candida. Filamentation does not appear to be a major determinant of the antifungal resistance in Candida biofilms

Transcriptional regulation of drug-resistance genes in Candida albicans biofilms in response to antifungals

Biofilm formation is a major virulence attribute of Candida albicans and is directly associated with therapeutic failure. One method by which Candida acquires antifungal resistance is the expression of drug-resistance genes. This study aimed to evaluate the transcriptional regulation of several genes associated with antifungal resistance of C. albicans under planktonic, recently adhered and biofilm growth modes and in C. albicans biofilms in response to antifungal agents. Initially, the antifungal susceptibility of C. albicans cultures in different growth modes was evaluated by standard antifungal susceptibility testing. Next, to assess CDR1, CDR2, MDR1, ERG11, FKS1 and PIL1 expression, RNA was harvested from cells in each growth mode, and from biofilms after drug treatment, and subjected to quantitative real-time RT-PCR (qRT-PCR). Biofilm C. albicans was more resistant to antifungals than recently adhered cells and stationaryphase planktonic cultures. Transcriptional expression of CDR1, CDR2, MDR1, ERG11 and FKS1 was lower in recently adhered C. albicans than in the stationary-phase planktonic cultures. In contrast, PIL1 levels were significantly increased in recently adhered and biofilm modes of growth. The expression of MDR1 in biofilms greatly increased on challenge with amphotericin B but not with the other drugs tested (