Global screening of potential <Emphasis Type="Italic">Candida albicans</Emphasis> biofilm-related transcription factors via network comparison

Background  

Candida albicans is a commonly encountered fungal pathogen in humans. The formation of biofilm is a major virulence factor in C. albicans pathogenesis and is related to antidrug resistance of this organism. Although many factors affecting biofilm have been analyzed, molecular mechanisms that regulate biofilm formation still await to be elucidated.     

Development and evaluation of different normalization strategies for gene expression studies in Candida albicans biofilms by real-time PCR

Background  

Candida albicans biofilms are commonly found on indwelling medical devices. However, the molecular basis of biofilm formation and development is not completely understood. Expression analysis of genes potentially involved in these processes, such as the ALS (Agglutinine Like Sequence) gene family can be performed using quantitative PCR (qPCR). In the present study, we investigated the expression stability of eight housekeeping genes potentially useful as reference genes to study gene expression in Candida albicans (C. albicans) biofilms, using the geNorm Visual Basic Application (VBA) for Microsoft Excel. To validate our normalization strategies we determined differences in ALS1 and ALS3 expression levels between C. albicans biofilm cells and their planktonic counterparts.     

Polyadenylation of ribosomal RNA by Candida albicans also involves the small subunit

Background  

Candida albicans is a polymorphic fungus causing serious infections in immunocompromised patients. It is capable of shifting from yeast to germinating forms such as hypha and pseudohypha in response to a variety of signals, including mammalian serum. We have previously shown that some of the large 25S components of ribosomal RNA in Candida albicans get polyadenylated, and this process is transiently intensified shortly after serum exposure just prior to the appearance of germination changes.     

Serum repressing efflux pump CDR1 in Candida albicans

Background  

In the past decades, the prevalence of candidemia has increased significantly and drug resistance has also become a pressing problem. Overexpression of CDR1, an efflux pump, has been proposed as a major mechanism contributing to the drug resistance in Candida albicans. It has been demonstrated that biological fluids such as human serum can have profound effects on antifungal pharmacodynamics. The aim of this study is to understand the effects of serum in drug susceptibility via monitoring the activity of CDR1 promoter of C. albicans.     

Experimental annotation of the human pathogen <Emphasis Type="Italic">Candida albicans</Emphasis> coding and noncoding transcribed regions using high-resolution tiling arrays

Background  

Compared to other model organisms and despite the clinical relevance of the pathogenic yeast Candida albicans, no comprehensive analysis has been done to provide experimental support of its in silico-based genome annotation.     

Ageing exacerbates damage of systemic and salivary neutrophils from patients presenting Candida-related denture stomatitis

Background  

Ageing leads to a decline in the function of the immune system, increasing the body's susceptibility to infections through the impairment of T-cells, macrophages, neutrophils and dendritic cells Denture stomatitis is a primary oral disease affecting elderly denture wearers. The major etiologic factor involved in this pathology is the infection by Candida albicans, an opportunistic pathogen that causes local and disseminated diseases in immunosuppressed humans. Neutrophils play a critical role in the immune response against C. albicans and are continually present in the salivary fluid and in the blood. The aim of this study was to determine ageing-related changes in salivary and blood neutrophils and their potential implications in Candida-related denture stomatitis.     

Characterization and partial purification of <Emphasis Type="Italic">Candida albicans</Emphasis> Secretory IL-12 Inhibitory Factor

Background  

We have previously shown that supernatant from Candida albicans (CA) culture contains a Secretory Interleukin (IL)-12 Inhibitory Factor (CA-SIIF), which inhibits IL-12 production by human monocytes. However, the effect of CA-SIIF on secretion of other cytokines by monocytes is unknown, and detailed characterization of this factor has not been performed.     

Protective effect of rifampicin and clindamycin impregnated devices against <Emphasis Type="Italic">Staphylococcus</Emphasis>spp. infection after cerebrospinal fluid diversion procedures

Background  

Infection is a major complication of cerebrospinal fluid shunting procedures. The present report assesses the efficacy of such catheters in both shunts and external ventricular drains (EVDs) against infection and particularly against Staphylococcus spp. infection.     

Real-time PCR expression profiling of genes encoding potential virulence factors in <Emphasis Type="Italic">Candida albicans</Emphasis> biofilms: identification of model-dependent and -independent gene expression

Background  

Candida albicans infections are often associated with biofilm formation. Previous work demonstrated that the expression of HWP1 (hyphal wall protein) and of genes belonging to the ALS (agglutinin-like sequence), SAP (secreted aspartyl protease), PLB (phospholipase B) and LIP (lipase) gene families is associated with biofilm growth on mucosal surfaces. We investigated using real-time PCR whether genes encoding potential virulence factors are also highly expressed in biofilms associated with abiotic surfaces. For this, C. albicans biofilms were grown on silicone in microtiter plates (MTP) or in the Centres for Disease Control (CDC) reactor, on polyurethane in an in vivo subcutaneous catheter rat (SCR) model, and on mucosal surfaces in the reconstituted human epithelium (RHE) model.     

Control of <Emphasis Type="Italic">gag-pol</Emphasis> gene expression in the <Emphasis Type="Italic">Candida albicans</Emphasis> retrotransposon Tca2

Background  

In the C. albicans retrotransposon Tca2, the gag and pol ORFs are separated by a UGA stop codon, 3' of which is a potential RNA pseudoknot. It is unclear how the Tca2 gag UGA codon is bypassed to allow pol expression. However, in other retroelements, translational readthrough of the gag stop codon can be directed by its flanking sequence, including a 3' pseudoknot.     

Evidence of recent interkingdom horizontal gene transfer between bacteria and <Emphasis Type="Italic">Candida parapsilosis</Emphasis>

Background  

To date very few incidences of interdomain gene transfer into fungi have been identified. Here, we used the emerging genome sequences of Candida albicans WO-1, Candida tropicalis, Candida parapsilosis, Clavispora lusitaniae, Pichia guilliermondii, and Lodderomyces elongisporus to identify recent interdomain HGT events. We refer to these as CTG species because they translate the CTG codon as serine rather than leucine, and share a recent common ancestor.     

Disruption of the GPI Protein-Encoding Gene <Emphasis Type="Italic">IFF4</Emphasis> of <Emphasis Type="Italic">Candida</Emphasis> <Emphasis Type="Italic">albicans</Emphasis> Results in Decreased Adherence and Virulence

Candida albicans is the most important cause of systemic fungal infection in immunocompromised humans. Candidiasis is often initiated by the adherence and the colonization of inert surfaces such as peripheral venous catheters, central catheters, prosthetic cardiac valves, and other prostheses. We have studied the early stage of adherence and have shown that the disruption of C. albicans IFF4 gene encoding a GPI-anchor protein, led to a decrease of adherence of the germ tubes to plastic. Here, we demonstrated the role of the IFF4 gene in adherence to silicone catheter, as well as in virulence using a murine model of disseminated candidiasis. The iff4 Δ null mutant showed both a decrease of adherence to silicone catheter and a reduction of virulence. This work presents evidence for the importance of the IFF4 gene in host-fungal interaction.     

Cationic nanoparticles for delivery of amphotericin B: preparation,characterization and activity <Emphasis Type="Italic">in vitro</Emphasis>

Background  

Particulate systems are well known to be able to deliver drugs with high efficiency and fewer adverse side effects, possibly by endocytosis of the drug carriers. On the other hand, cationic compounds and assemblies exhibit a general antimicrobial action. In this work, cationic nanoparticles built from drug, cationic lipid and polyelectrolytes are shown to be excellent and active carriers of amphotericin B against C. albicans.     

Design of a Simple Model of <Emphasis Type="Italic">Candida albicans</Emphasis> Biofilms Formed under Conditions of Flow: Development,Architecture, and Drug Resistance

Candida albicans biofilms on most medical devices are exposed to a flow of body fluids that provide water and nutrients to the fungal cells. While C. albicans biofilms grown in vitro under static conditions have been exhaustively studied, the same is not true for biofilms developed under continuous flow of replenishing nutrients. Here, we describe a simple flow biofilm (FB) model that can be built easily with materials commonly available in most microbiological laboratories. We demonstrate that C. albicans biofilms formed using this flow system show increased architectural complexity compared to biofilms grown under static conditions. C. albicans biofilms under continuous medium flow grow rapidly, and by 8 h show characteristics similar to 24 h statically grown biofilms. Biomass measurements and microscopic observations further revealed that after 24 h of incubation, FB was more than twofold thicker than biofilms grown under static conditions. Microscopic analyses revealed that the surface of these biofilms was extremely compact and wrinkled, unlike the open hyphal layer typically seen in 24 h static biofilms. Results of antifungal drug susceptibility tests showed that C. albicans cells in FB exhibited increased resistance to most clinically used antifungal agents.     

<Emphasis Type="Italic">Candida albicans SUR7</Emphasis> contributes to secretion,biofilm formation,and macrophage killing

Background  

Candida albicans SUR7 has been shown to be required for plasma membrane organization and cell wall synthesis, but its role in virulence is not known. Using a bioinformatics strategy, we previously identified several novel putative secretion pathway proteins potentially involved in virulence, including the C. albicans homolog of the Saccharomyces cerevisiae endocytosis-related protein Sur7p. We therefore generated a C. albicans sur7Δ null mutant and examined its contribution to key virulence attributes.     

Role of type 1 and type 3 fimbriae in <Emphasis Type="Italic">Klebsiella pneumoniae</Emphasis> biofilm formation

Background  

Klebsiella pneumoniae is an important gram-negative opportunistic pathogen causing primarily urinary tract infections, respiratory infections, and bacteraemia. The ability of bacteria to form biofilms on medical devices, e.g. catheters, has a major role in development of many nosocomial infections. Most clinical K. pneumoniae isolates express two types of fimbrial adhesins, type 1 fimbriae and type 3 fimbriae. In this study, we characterized the role of type 1 and type 3 fimbriae in K. pneumoniae biofilm formation.     

Use of Pistacia lentiscus mastic for sustained-release system of chlorocresol and benzoic acid for in vitro prevention of bacterial colonization of silicon urinary catheter

Urinary tract infections (UTI) are among the most common types of nosocomial infections. Patients with indwelling urinary catheters are at the highest risk of getting infections. A sustained-release method of chlorocresol and benzoic acid using a varnish of Pistacia lentiscus mastic was developed to prevent catheter colonization by Staphylococcus epidermidis, Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis and Pseudomonas aeruginosa. Coatings of both antiseptics significantly reduced the number of colonizing bacteria on silicon urinary catheters for 72 h. Chlorocresol-coated catheters were significantly (P ≤ 0·05) more effective than benzoic acid. Except for the Pr. mirabilis, chlorocresol completely inhibited the colonization of catheters by the tested bacteria for 48 h. Nonetheless, the colonization of catheters by Pr. mirabilis was significantly reduced after 48 and 72 h by more than 3·5 logs. Although benzoic acid failed to completely inhibit bacterial growth, it significantly reduced the colonization of the catheters by all the tested bacteria by more than two logs for 72 h. The inhibition of colonization of catheters was confirmed by examining the tested catheters by scanning electron microscopy. The obtained results indicate the potential benefits of using mastic as a varnish for sustaining the release of chlorocresol and benzoic acid to prevent and reduce the colonization of urinary catheters by bacteria.     

The effect of chlorhexidine and gentian violet on the adherence of <Emphasis Type="Italic">Candida</Emphasis> spp. to urinary catheters

Urinary tract infection associated with catheters is the most common infection in the hospital environment. The adherence of microorganisms to the surface is a determining factor in colonization and infection. Antiseptics such as chlorhexidine and gentian violet have been shown to be effective against yeasts, as well as having low toxicity and being low-cost. The objective of the present study was to evaluate whether prior treatment of siliconized latex urinary catheters with antiseptics reduces the adherence of yeasts. Two reference strains of C. albicans (ATCC 645448 and ATCC 90028) and six strains isolated from catheter, two each of C. albicans, C. tropicalis, and C. parapsilosis, were used. An in␣vitro study of adherence was carried out with previously treated catheters, in separate experiments of 1 h and 24 h of incubation under continued shaking. The relative hydrophobicity of the cell surface of the yeasts before and after 1 h of exposure to chlorhexidine was determined. The results demonstrated that both treatments were effective in controlling the adherence of yeast to the catheter (P < 0.0001), and that the hydrophobicity of the eight strains significantly increased after contact with chlorhexidine (P < 0.0001). These results suggest that the antimicrobial activity of chlorhexidine and gentian violet reduces the adherence of the microorganisms to the catheter.     

In vitro assay of the antimicrobial activity of kephir against bacterial and fungal strains

Kephir is a fermented carbonated refreshing milk, with a slightly acidic aromatic taste and creamy foam composition which contains lactobacilli, leuconostocci, acetic acid bacteria, lactostreptococci and yeasts. Recent studies have demonstrated its antibacterial, immunostimulating, antitumoral and cholesterol-lowering activities.

Purpose

The purpose of this study was to investigate the antimicrobial activity of kephir against Bacillus subtilis spp. spizizenii ATCC 6633, Staphylococcus aureus ATCC 6538, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 8739, Salmonella enteritidis ATCC 13076, Pseudomonas aeruginosa ATCC 9027 and Candida albicans ATCC 10231. The kephir fermented for 24 h and 48 h, as well and after 7 days preservation at 4–8 °C was tested by in vitro disk diffusion method. The intensity of the antimicrobial activity was interpreted by comparison with two antibiotics, i.e. ampicillin and neomycin.

Results

The antimicrobial activity of 24 h as well as 48 fermented kephir, fresh or after 7 days preservation at 4–8 °C was similar and observed against B. subtilis, S. aureus, E. coli, E. faecalis and S. enteritidis. For E. coli, E. faecalis and S. enteritidis the antimicrobial activity was superior to both tested antibiotics and for B. subtilis and S. aureus to one antibiotic. The tested products exhibited no activity against P. aeruginosa and C. albicans.

Conclusion

Kephir is exhibiting large spectrum and strong antibacterial activity probably due to the complex viable probiotic strains association producing antimicrobial substances.     

<Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> inhibits <Emphasis Type="Italic">in-vitro Candida</Emphasis> biofilm development

Background  

Elucidation of the communal behavior of microbes in mixed species biofilms may have a major impact on understanding infectious diseases and for the therapeutics. Although, the structure and the properties of monospecies biofilms and their role in disease have been extensively studied during the last decade, the interactions within mixed biofilms consisting of bacteria and fungi such as Candida spp. have not been illustrated in depth. Hence, the aim of this study was to evaluate the interspecies interactions of Pseudomonas aeruginosa and six different species of Candida comprising C. albicans, C. glabrata, C. krusei, C. tropicalis, C. parapsilosis, and C. dubliniensis in dual species biofilm development.