Identification of virulence factors in isolates of Candida haemulonii, Candida albicans and Clavispora lusitaniae with low susceptibility and resistance to fluconazole and amphotericin B

Emerging life-threatening multidrug-resistant (MDR) species such as the C. haemulonii species complex, Clavispora lusitaniae (sin. C. lusitaniae), and other Candida species are considered as an increasing risk for human health in the near future. (1) Background: Many studies have emphasized that the increase in drug resistance can be associated with several virulence factors in Candida and its knowledge is also essential in developing new antifungal strategies. (2) Methods: Hydrophobicity, adherence, biofilm formation, lipase activity, resistance to osmotic stress, and virulence 'in vivo' on G. mellonella larvae were studied in isolates of C. haemulonii, C. albicans, and C. lusitaniae with low susceptibility and resistance to fluconazole and amphotericin B. (3) Results: Intra- and interspecies variability were observed. C. haemulonii showed high hydrophobicity and the ability to adhere to and form biofilm. C. lusitaniae was less hydrophobic, was biofilm-formation-strain-dependent, and did not show lipase activity. Larvae inoculated with C. albicans isolates displayed significantly higher mortality rates than those infected with C. haemulonii and C. lusitaniae. (4) Conclusions: The ability to adhere to and form biofilms associated with their hydrophobic capacity, to adapt to stress, and to infect within an in vivo model, observed in these non-wild-type Candida and Clavispora isolates, shows their marked virulence features. Since factors that define virulence are related to the development of the resistance of these fungi to the few antifungals available for clinical use, differences in the physiology of these cells must be considered to develop new antifungal therapies

Beneficial effect of Mentha suaveolens essential oil in the treatment of vaginal candidiasis assessed by real-time monitoring of infection

<p>Abstract</p> <p>Background</p> <p>Vaginal candidiasis is a frequent and common distressing disease affecting up to 75% of the women of fertile age; most of these women have recurrent episodes. Essential oils from aromatic plants have been shown to have antimicrobial and antifungal activities. This study was aimed at assessing the anti-fungal activity of essential oil from <it>Mentha suaveolens </it>(EOMS) in an experimental infection of vaginal candidiasis.</p> <p>Methods</p> <p>The <it>in vitro </it>and <it>in vivo </it>activity of EOMS was assessed. The <it>in vitro </it>activity was evaluated under standard CLSI methods, and the <it>in vivo </it>analysis was carried out by exploiting a novel, non-invasive model of vaginal candidiasis in mice based on an <it>in vivo </it>imaging technique.</p> <p>Differences between essential oil treated and saline treated mice were evaluated by the non-parametric Mann-Whitney U-test. Viable count data from a time kill assay and yeast and hyphae survival test were compared using the Student's t-test (two-tailed).</p> <p>Results</p> <p>Our main findings were: i) EOMS shows potent candidastatic and candidacidal activity in an <it>in vitro </it>experimental system; ii) EOMS gives a degree of protection against vaginal candidiasis in an <it>in vivo </it>experimental system.</p> <p>Conclusions</p> <p>This study shows for the first time that the essential oil of a Moroccan plant <it>Mentha suaveolens </it>is candidastatic and candidacidal <it>in vitro</it>, and has a degree of anticandidal activity in a model of vaginal infection, as demonstrated in an <it>in vivo </it>monitoring imaging system. We conclude that our findings lay the ground for further, more extensive investigations to identify the active EOMS component(s), promising in the therapeutically problematic setting of chronic vaginal candidiasis in humans.</p

Chromatographic Analyses, In Vitro Biological Activities, and Cytotoxicity of Cannabis sativa L. Essential Oil: A Multidisciplinary Study

Due to renewed interest in the cultivation and production of Italian Cannabis sativa L., we proposed a multi-methodological approach to explore chemically and biologically both the essential oil and the aromatic water of this plant. We reported the chemical composition in terms of cannabinoid content, volatile component, phenolic and flavonoid pattern, and color characteristics. Then, we demonstrated the ethnopharmacological relevance of this plant cultivated in Italy as a source of antioxidant compounds toward a large panel of enzymes (pancreatic lipase, -amylase, -glucosidase, and cholinesterases) and selected clinically relevant, multidrug-sensible, and multidrug-resistant microbial strains (Staphylococcus aureus, Helicobacter pylori, Candida, and Malassezia spp.), evaluating the cytotoxic effects against normal and malignant cell lines. Preliminary in vivo cytotoxicity was also performed on Galleria mellonella larvae. The results corroborate the use of this natural product as a rich source of important biologically active molecules with particular emphasis on the role exerted by naringenin, one of the most important secondary metabolites

Surface-Associated Plasminogen Binding of Cryptococcus neoformans Promotes Extracellular Matrix Invasion

BACKGROUND:The fungal pathogen Cryptococcus neoformans is a leading cause of illness and death in persons with predisposing factors, including: malignancies, solid organ transplants, and corticosteroid use. C. neoformans is ubiquitous in the environment and enters into the lungs via inhalation, where it can disseminate through the bloodstream and penetrate the central nervous system (CNS), resulting in a difficult to treat and often-fatal infection of the brain, called meningoencephalitis. Plasminogen is a highly abundant protein found in the plasma component of blood and is necessary for the degradation of fibrin, collagen, and other structural components of tissues. This fibrinolytic system is utilized by cancer cells during metastasis and several pathogenic species of bacteria have been found to manipulate the host plasminogen system to facilitate invasion of tissues during infection by modifying the activation of this process through the binding of plasminogen at their surface. METHODOLOGY:The invasion of the brain and the central nervous system by penetration of the protective blood-brain barrier is a prerequisite to the establishment of meningoencephalitis by the opportunistic fungal pathogen C. neoformans. In this study, we examined the ability of C. neoformans to subvert the host plasminogen system to facilitate tissue barrier invasion. Through a combination of biochemical, cell biology, and proteomic approaches, we have shown that C. neoformans utilizes the host plasminogen system to cross tissue barriers, providing support for the hypothesis that plasminogen-binding may contribute to the invasion of the blood-brain barrier by penetration of the brain endothelial cells and underlying matrix. In addition, we have identified the cell wall-associated proteins that serve as plasminogen receptors and characterized both the plasminogen-binding and plasmin-activation potential for this significant human pathogen. CONCLUSIONS:The results of this study provide evidence for the cooperative role of multiple virulence determinants in C. neoformans pathogenesis and suggest new avenues for the development of anti-infective agents in the prevention of fungal tissue invasion

Antimicrobial and Antioxidant Activities of Natural Compounds

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Induction of germ tube formation by N-acetyl-D-glucosamine in Candida albicans: uptake of inducer and germinative response.

A number of strains of Candida albicans were tested for germ tube formation after induction by N-acetyl-D-glucosamine (GlcNAc) and other simple (proline, glucose plus glutamine) or complex (serum) compounds. A proportion of strains (high responders) were induced to form germ tubes evolving to true hyphae by GlcNAc alone or by proline or glucose plus glutamine mixture. The majority of strains were low responders because they could be induced only by serum or GlcNAc-serum medium. Two strains were found to be nonresponders: they grew as pseudohyphae in serum. Despite minor quantitative differences, all strains efficiently utilized GlcNAc for growth under the yeast form at 28 degrees C. They also had comparable active, inducible, and constitutive uptake systems for GlcNAc. During germ tube formation in GlcNAc, the inducible uptake system was modulated, as expected from induction and decay of GlcNAc kinase. Uranyl acetate, at a concentration of 0.01 mM, inhibited both GlcNAc uptake and germ tube formation and was reversed by phosphates. Germinating and nongerminating cells differed in the rapidity and extent of GlcNAc incorporation into acid-insoluble and alkali-acid-insoluble cell fractions. During germ tube formation induced by proline, GlcNAc was almost totally incorporated into the acid-insoluble fraction after 60 min. Moreover, hyphal development on induction by either GlcNAc or proline was characterized by an apparent "uncoupling" between protein and polysaccharide metabolism, the ratio between the two main cellular constituents falling from more than 1 to less than 0.5 after 270 min of development. The data suggest that utilization of the inducer for wall synthesis is a determinant of germ tube formation C. albicans but that the nature and extent of inducer uptake is not a key event for this phenomenon to occur

Induction of germ tube formation by N-acetyl-D-glucosamine in Candida albicans: uptake of inducer and germinative response

A number of strains of Candida albicans were tested for germ tube formation after induction by N-acetyl-D-glucosamine (GlcNAc) and other simple (proline, glucose plus glutamine) or complex (serum) compounds. A proportion of strains (high responders) were induced to form germ tubes evolving to true hyphae by GlcNAc alone or by proline or glucose plus glutamine mixture. The majority of strains were low responders because they could be induced only by serum or GlcNAc-serum medium. Two strains were found to be nonresponders: they grew as pseudohyphae in serum. Despite minor quantitative differences, all strains efficiently utilized GlcNAc for growth under the yeast form at 28 degrees C. They also had comparable active, inducible, and constitutive uptake systems for GlcNAc. During germ tube formation in GlcNAc, the inducible uptake system was modulated, as expected from induction and decay of GlcNAc kinase. Uranyl acetate, at a concentration of 0.01 mM, inhibited both GlcNAc uptake and germ tube formation and was reversed by phosphates. Germinating and nongerminating cells differed in the rapidity and extent of GlcNAc incorporation into acid-insoluble and alkali-acid-insoluble cell fractions. During germ tube formation induced by proline, GlcNAc was almost totally incorporated into the acid-insoluble fraction after 60 min. Moreover, hyphal development on induction by either GlcNAc or proline was characterized by an apparent "uncoupling" between protein and polysaccharide metabolism, the ratio between the two main cellular constituents falling from more than 1 to less than 0.5 after 270 min of development. The data suggest that utilization of the inducer for wall synthesis is a determinant of germ tube formation C. albicans but that the nature and extent of inducer uptake is not a key event for this phenomenon to occur.</jats:p

Glucan synthesis and its inhibition by cilofungin in susceptible and resistante strains of Candida albicans.

The lipopeptide antimycotic agent, cilofungin, at a dose of 20 micrograms ml-1, inhibited beta 1-3 glucan synthesis in a drug-susceptible strain (3153; minimum inhibitory concentration (MIC) 50 micrograms ml-1). This was demonstrated for both whole cells under growing and non-growing conditions, and during protoplast regeneration. However, time-effect experiments, during growth of a CA-2 culture initially exposed to an inhibitory dose of cilofungin, showed that this strain was able to progressively regain both glucan synthesis and a growth rate comparable to that of cultures that had not been treated with the drug. This recovery was not attributable to cilofungin instability or degradation within the CA-2 culture. Our study suggests the existence of an as yet unknown drug-related and/or cell-related factor(s) modulating the inhibition of glucan synthesis, and then contributing to the actual inhibitory effects of cilofungin in C. albicans