Exploration of Brazilian biodiversity and selection of a new oleaginous yeast strain cultivated in raw glycerol

The objective of this study was to use glycerol generated from the synthesis of biodiesel to study the oleaginous potential of wild yeasts. An initial selection was performed via a rapid and qualitative technique by staining with Sudan Black B. Initially 129 yeasts were present, from which 5 were selected and cultivated in liquid medium containing pure or raw glycerol. The yeast LEB-M3, isolated from the Pantanal, presented lipid content of 20.46% and 56.58% for cultivation in pure and raw glycerol, respectively. This strain was genotypically identified as Candida sp. The fatty acid profile showed predominance of oleic acid (C18:1), 57.35% for cultivation in pure glycerol, and in raw glycerol linoleic acid (C18:2) was predominant (46.0%). It was possible to select a yeast with high lipid concentrations 9.14 g/L and fatty acid profile similar to vegetable oils commonly used in the synthesis of biodiesel.

The Burkholderia contaminans MS14 ocfC gene encodes a xylosyltransferase for production of the antifungal occidiofungin

Burkholderia contaminans strain MS14 produces the antifungal compound occidiofungin, which is responsible for significant antifungal activities against a broad range of plant and animal fungal pathogens. Occidiofungin is a cyclic glycolipopeptide made up of eight amino acids and one xylose. A 56-kb ocf gene cluster was determined to be essential for occidiofungin production. In this study, the ocfC gene, which is located downstream of ocfD and upstream of the ocfB gene in the ocf gene cluster, was examined. Antifungal activity of the ocfC gene mutant MS14KC1 was reduced against the indicator fungus Geotrichum candidum compared with that of the wild-type strain. Furthermore, the analysis of the protein sequence suggests that the ocfC gene encodes a glycosyltransferase. Biochemical analyses using nuclear magnetic resonance (NMR) and mass spectroscopy revealed that the ocfC mutant produced the occidiofungin without the xylose. The purified ocfC mutant MS14KC1 product had a level of bioactivity similar to that of the wild-type product. The revertant MS14KC1-R of the ocfC mutant produced the same antifungal activity level on plate assays and the same antifungal compound based on high-performance liquid chromatography (HPLC) and mass spectroscopy analysis as wild-type strain MS14. Collectively, the study demonstrates that the ocfC gene encodes a glycosyltransferase responsible to add a xylose to the occidiofungin molecule and that the presence of the xylose is not important for antifungal activity against Candida species. The finding provides a novel variant for future studies aimed at evaluating its use for inhibiting clinical and agricultural fungi, and the finding could also simplify the chemical synthesis of occidiofungin variants.

Candida guilliermondii: biotechnological applications, perspectives for biological control, emerging clinical importance and recent advances in genetics

Candida guilliermondii (teleomorph Meyerozyma guilliermondii) is an ascomycetous species belonging to the Saccharomycotina CTG clade which has been studied over the last 40 years due to its biotechnological interest, biological control potential and clinical importance. Such a wide range of applications in various areas of fundamental and applied scientific research has progressively made C. guilliermondii an attractive model for exploring the potential of yeast metabolic engineering as well as for elucidating new molecular events supporting pathogenicity and antifungal resistance. All these research fields now take advantage of the establishment of a useful molecular toolbox specifically dedicated to C. guilliermondii genetics including the construction of recipient strains, the development of selectable markers and reporter genes and optimization of transformation protocols. This area of study is further supported by the availability of the complete genome sequence of the reference strain ATCC 6260 and the creation of numerous databases dedicated to gene ontology annotation (metabolic pathways, virulence, and morphogenesis). These genetic tools and genomic resources represent essential prerequisites for further successful development of C. guilliermondii research in medical mycology and in biological control by facilitating the identification of the multiple factors that contribute to its pathogenic potential. These genetic and genomic advances should also expedite future practical uses of C. guilliermondii strains of biotechnological interest by opening a window into a better understanding of the biosynthetic pathways of valuable metabolites.

Novel α-MSH peptide analogues with broad spectrum antimicrobial activity

Previous investigations indicate that α-melanocyte-stimulating hormone (α-MSH) and certain synthetic analogues of it exert antimicrobial effects against bacteria and yeasts. However, these molecules have weak activity in standard microbiology conditions and this hampers a realistic clinical use. The aim in the present study was to identify novel peptides with broad-spectrum antimicrobial activity in growth medium. To this purpose, the Gly10 residue in the [DNal(2′)-7, Phe-12]-MSH(6–13) sequence was replaced with conventional and unconventional amino acids with different degrees of conformational rigidity. Two derivatives in which Gly10 was replaced by the residues Aic and Cha, respectively, had substantial activity against Candida strains, including C. albicans, C. glabrata, and C. krusei and against gram-positive and gram-negative bacteria. Conformational analysis indicated that the helical structure along residues 8–13 is a key factor in antimicrobial activity. Synthetic analogues of α-MSH can be valuable agents to treat infections in humans. The structural preferences associated with antimicrobial activity identified in this research can help further development of synthetic melanocortins with enhanced biological activity.

[Fungicidal activity of yeast isolated from chal (camel cultured milk product)]

A Kluyveromyces strain secreting a fungicidal proteinaceous toxin has been isolated. Its maximal activity is observed at pH 5.0 and an increased osmotic pressure. This agent has been identified as a mycocin; it is active towards species belonging to the genus Kluyveromyces and some representatives of taxonomically related groups.

[Biological decontamination of the imprints obtained from different dental materials]

Microbiological contamination of the imprints made of alginate ("Ypeen") and silicone material ("Speedex") with and without the correction supplement has been investigated. Streptococcus and Staphylococcus have been estimated to be the most survivable species on the imprint surface, however their concentration differ depending on the type of imprints' material. The strains resistant to antibiotics dominated among all the isolated microorganisms. Bacterial preparations based on Bacillus - Biosporin and Subalin and some extracts of edible plants, fruits and berries can be used in dentistry for the decontamination of imprints obtained by the use of different materials.

[Pattern dynamics of bacteriemia and sepsis pathogens in ICU patients of emergency service]

The results of microbiological tests of 2382 blood specimens from 698 patients of three ICUs of the N. V. Sklifosovsky Research Institute of Emergency Service were analysed for a period of 2009 to 2012. No microbial growth was detected in 1160 specimens (48.7%). In the subsequent tests 816 isolates were used. The quota of grampositive isolates in the pathogen pattern decreased from 51.68 to 35.9% and that of gramnegative isolates increased from 38.26 to 48.1%. The number of the Candida isolates increased from 7.38 to 15.2%. The frequency of the S. aureus and Enterococcus spp. isolates lowered from 26.2 to 13.3% and from 15.4 to 11.5% respectively. The quota of K. pneumoniae isolates and Acinetobacter spp. increased from 8.1 to 18.9% and from 14.1 to 17.4% respectively. Most of the S. aureus isolates were methicillin resistant. All the staphylococcal isolates were susceptible to vancomycin and linezolid. All the strains of K. pneumoniae isolated in 2009-2012 produced extended spectrum beta-lactamases. In 2012 7.8% the K. pneumoniae isolates were resistant to carbapenems. In 2012 25.5% of the Acinetobacter spp. isolates were susceptible to carbapenems and 70.2% were susceptible to cefoperazon/sulbactam.

Microwave irradiation as an alternative method for disinfection of denture base acrylic resins

AIM

This study evaluated the effect of microwave irradiation as an alternative method for disinfection of different types of denture base acrylic resins.

METHODS

Twenty-four samples for each conventional, microwaved and characterized heat-cured acrylic resin were made and subjected to sterilization with ethylene oxide for the groups: 1) irradiated samples; 2) non-irradiated samples; and 3) samples without yeast. Each group was subdivided according to inoculation with C. albicans, C. dubliniensis and C. tropicalis. The samples were inoculated with 100 µL of inoculum of each species of Candida and later placed in an incubator at 37 °C for 1 hr to perform the first adhesion. After this time, each well was supplemented with sterile media and the plate was once again taken to a stove for incubation at 37 °C for 6 hr. The samples were immersed in 100 mL of sterile water and irradiated with microwave at 650 W for 3 min. Control samples were considered as the non-irradiated group. After incubation for 48 hr, irradiated and non-irradiated samples were subjected to a digital colony counter.

RESULTS

Control group (non-irradiated) showed microbial growth for resins and the means of ufc/mL were without statistically significant differences. Microwave irradiated samples (experimental group) promoted no viable colonies for all Candida species and types of acrylic resins. The means of ufc/mL were without statistically significant differences.

CONCLUSION

Microwave irradiation was an effective method for disinfection of the acrylic resins inoculated with C. albicans, C. dubliniensis and C. tropicalis.

Citric acid production by Candida species grown on a soy-based crude glycerol

Citric acid was produced by five species of the yeast Candida after growth on a medium containing soy biodiesel-based crude glycerol. After growth on a medium containing 10 g L(-1) or 60 g L(-1) crude glycerol for 168 hr at 30°C, Candida parapsilosis ATCC 7330 and C. guilliermondii ATCC 9058 produced the highest citric acid levels. On 10 g L(-1) or 60 g L(-1) crude glycerol for 168 hr at 30°C, the citric acid level produced by C. parapsilosis ATCC 7330 was 1.8 g L(-1) or 11.3 g L(-1), respectively, while C. guilliermondii ATCC 9058 produced citric acid concentrations of 3.0 g L(-1) or 10.4 g L(-1), respectively. Biomass production by C. guilliermondii ATCC 9058 on 10 g L(-1) or 60 g L(-1) crude glycerol for 168 hr at 30°C was highest at 1.2 g L(-1) or 6.9 g L(-1), respectively. The citric acid yields observed for C. guilliermondii ATCC 9058 after growth on 10 g L(-1) or 60 g L(-1) crude glycerol (0.35 g g(-1) or 0.21 g g(-1), respectively) were generally higher than for the other Candida species tested. When similar crude glycerol concentrations were present in the culture medium, citric acid yields observed for some of the Candida species utilized in this study were about the same or higher compared to citric acid yields by Yarrowia lipolytica strains. Based on the findings, it appeared that C. guilliermondii ATCC 9058 was the most effective species utilized, with its citric acid production being similar to what has been observed when citric acid-producing strains of Y. lipolytica were grown on crude glycerol under batch conditions that could be of significance to biobased citric acid production.

Selenium-enriched Candida utilis: Efficient preparation with l-methionine and antioxidant capacity in rats

Selenium-enriched Candida utilis has attracted much attention due to its expanding application in food and feed additives. The objective of this study was to efficiently prepare selenium-enriched C. utilis and to investigate the effects of the prepared yeast on antioxidant capacity in rats. A batch culture of selenium-enriched C. utilis was first carried out, and the addition of sodium selenite (Na(2)SeO(3)) after all glucose had been consumed was found to favor higher intracellular glutathione and organic selenium content. Moreover, l-methionine boosted yeast cell growth and glutathione biosynthesis, and prevented glutathione from leaking to the extracellular space that can be caused by Na(2)SeO(3). We therefore developed a two-stage culture strategy involving supplementation with l-methionine and Na(2)SeO(3) at separate culture phases to improve the performance of selenized C. utilis. Using this two-stage culture strategy, intracellular glutathione content reached 18.6 mg/g and 15.5mg/g, respectively, in batch and fed-batch systems, and organic selenium content reached 905.2 μg/g and 984.7 μg/g, respectively. The effects of selenium-enriched C. utilis on the activities of antioxidant related enzymes in rats were investigated, and the prepared selenium-enriched C. utilis was shown to be an optimal dietary supplement for enhancing antioxidant capacity in rats.

[Dioxidin: antimicrobial activity and prospects of its clinical use at present]

In vitro activity of dioxidin against pathogens of nosocomial infections and its cytotoxicity were estimated. The study involved 300 isolates from patients with nosocomial infections. The MICs of dioxidin were determined with the method of serial dilutions in broth. The dioxidin cytotoxicity was investigated with the MTI assay to assign the cell culture viability. In concentrations of 2 to 1024 meg/mi dioxidin was active against 279/300 (93%) strains. The drug inhibited the growth of all the gramnegative isolates. The highest activitywas observed against Enterobacteriaceae vs. nonfermenting gramnegative bacteria: the median, minimum and maximum MICs of dioxidin were 12 (4-32) and 32 (16-64) mcg/ml respectively. The dioxidin activity against gramnegative bacteria and fungi was lower. The MIC of dioxidin for 7/70 (10%) staphylococcal isolates, 9/28 (32%) enterococcal isolates and all the Candida isolates was > 1024 mcg/ml. The IC50 of dioxidin was 2.4+/-0.3 mM (low cytotoxicity). The results showed that the use of dioxidin as an antimicrobial for local application was advisable in the treatment of gramnegative bacterial infections provided adequate tissue concentrations were attained.

Alcohol and acetaldehyde in African fermented milk mursik--a possible etiologic factor for high incidence of esophageal cancer in western Kenya

BACKGROUND

Esophageal cancer is unusually frequent in Western Kenya, despite the low prevalence of classical risk factors such as heavy drinking and tobacco smoking. Among Kenyans consumption of fermented milk is an old tradition. Our hypothesis is that alcohol and acetaldehyde are produced during the fermentation process and that their carcinogenic potential contributes to the high incidence of esophageal cancer.

METHODS

Eight samples of mursik milk starter cultures were collected from different Kalenjin families in the Rift Valley province, Western Kenya. A protocol provided by the families was used for milk fermentation. Ethanol and acetaldehyde levels were measured by gas chromatography. The microbial flora in starter cultures was identified by 16S and 18S sequencing.

RESULTS

7/8 starter cultures produced mutagenic (>100 μmol/L) levels of acetaldehyde and 4/8 starter cultures produced more than 1,000 μmol/L of acetaldehyde. The highest alcohol levels (mean 79.4 mmol/L) were detected in the four fermented milks with highest acetaldehyde production. The mean number of microbial species in the starter cultures was 5 (range 2-8). Yeasts were identified in all starter cultures (mean 1.5 species/milk) but their proportion of the total microbial count varied markedly (mean 35%, range 7%-90%). A combination of yeast and lactobacilli, especially Candida krusei with Lactobacillus kefiri, with the exclusion of other species, seemed to correlate with higher acetaldehyde and ethanol levels.

CONCLUSIONS

Significant levels of ethanol and acetaldehyde were produced during mursik fermentation.

IMPACT

When ingested several times daily the repeated exposure to carcinogenic levels of acetaldehyde may contribute to esophageal carcinogenesis.

Efficient preparation of selenium/glutathione-enriched Candida utilis and its biological effects on rats

The main purpose of this study was to prepare selenium/glutathione-enriched Candida utilis and investigate its effect on growth performance, antioxidant capacity, and immune response in rats. The preparation of the selenium/glutathione-enriched yeast was conducted using fed-batch culture for high cell density. The optimal culture conditions for increased intracellular organic selenium and glutathione contents were as follows: the concentrated medium was fed beginning at 12 h using a polynomial feeding strategy until a total glucose concentration of 150 g/l was reached, and sodium selenite was continuously added together with glucose to a total concentration of 60 mg/l. As a result, 81 % of sodium selenite was assimilated and transformed into organic selenium by C. utilis under optimal conditions, which in turn resulted in greater glutathione accumulation and lower malondialdehyde cellular content in the yeast. To investigate and compare the effects of the prepared selenized C. utilis and other dietary supplements, 40 female rats were divided into five groups of eight rats each, following a randomized block design. Experimental feeding was conducted for a period of 6 weeks. Selenium supplementation with inorganic selenium (sodium selenite) and organic selenium (selenized C. utilis) showed better results than the control and other groups supplemented with yeast with or without glutathione. The body mass of rats, selenium deposition, and oxidative enzymes activities in both serum and liver samples, and immunity responses were all significantly improved by selenium supplementation, and between the two sources, organic selenium was more effective than inorganic selenium.

Evaluation of the Sensititre Yeast One microdilution method for susceptibility testing of Candida species to anidulafungin, caspofungin, and micafungin

INTRODUCTION

Echinocandins represent a new antifungal group with potent activity against Candida species. The purpose of our study was to evaluate the utility of the Sensititre Yeast One method to determine the in vitro activity of anidulafungin, micafungin, and caspofungin against Candida species isolated from clinical specimens.

METHODS

A total of 131 Candida strains were tested using Sensititre Yeast One colorimetric microdilution method. They belonged to the following species: 42 C. albicans, 36 C. glabrata, 21 C. parapsilosis, 12 C. tropicalis, 10 C. krusei, 3 C. guilliermondii, 2 C. famata, 3 C. kefyr, 1 C. lusitaniae, 1 C. zeylanoides, and 1 C. lipolytica. For being considered susceptible the strains had to be inhibited by concentrations ≤2 mg/L of anidulafungin, caspofungin or micafungin.

RESULTS

The 80.1% of the strains tested were inhibited by concentrations ≤0.25 mg/L of anidulafungin and micafungin. The activity of caspofungin was slightly lower (78.6% of strains inhibited by concentrations ≤0.25 mg/L). The 96.9% of strains turned out susceptible to concentrations ≤2 mg/L against the three echinocandins. Two strains of C. parapsilosis (9.5%), one of C. guilliermondii, and two of C. famata showed non-susceptible to one or more echinocandins.

CONCLUSIONS

In our series, anidulafungin, micafungin, and caspofungin were effective against C. albicans, C. glabrata, C. tropicalis, C. krusei, C. kefyr, C. lusitaniae and C. lipolytica. The 96.9% of strains were susceptible to all three echinocandins. Thus, echinocandins are proved to exhibit excellent activity to the Candida species most frequently involved in human infections, except Candida parapsilosis.

Antimicrobial activity of plants used as medicinals on an indigenous reserve in Rio das Cobras, Paraná, Brazil

ETHNOPHARMACOLOGICAL RELEVANCE

A considerable percentage of global biodiversity is located in Brazil, a country that also has rich cultural and ethnic diversity. In the community of Rio das Cobras, Paraná, plants are still widely used in the health care not only by indigenous people but also by the non-indigenous population that inhabits the region. The investigation of the efficacy and safety of these plants in the treatment of infectious diseases provides insights for future studies of these species allowing the appropriated use by the indigenous people, since few or none study has been conducted so far.

AIM OF THE STUDY

Evaluate the antimicrobial activity and cytotoxicity of some plants used as medicinal on an indigenous reserve in Rio das Cobras, Paraná, Brazil.

MATERIALS AND METHODS

The aqueous extracts were obtained by decoction and the 50% and 70% hydroalcoholic extracts by turbo extraction. The extracts were tested against strains of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, Candida albicans, Candida parapsilosis, Candida tropicalis, Leishmania amazonensis, Poliovirus and HSV-1. Cytotoxicity assay using VERO cells were also performed.

RESULTS

None of the extracts had a selectivity index (SI)>1 for any of the tested bacteria. Only Campomanesia eugenioides and Schinus terebinthifolius had an SI>1.0 for all of the tested Candida species. The best anti-Leishmania activity was obtained with Zanthoxylum rhoifolium and Schinus terebinthifolius. Extracts of Cordia americana were the most effective against herpes simplex virus type 1. Zanthoxylum rhoifolium was the most effective against Poliovirus, and Ocimum gratissimum was effective against both Poliovirus and Herpes Simplex virus. Among the plants investigated in the present study, Zanthoxylum rhoifolium had the fewest cytotoxic effect.

CONCLUSIONS

The plants investigated in the present study exhibited potential for future pharmacological uses, but additional studies, especially with regard to in vivo toxicity, must be conducted. The results of this preliminary survey are important for the Rio das Cobras Reserve community for the safe and effective use of plants in the treatment of some infectious diseases.

Oral Candida colonization and candidiasis in patients with psoriasis

OBJECTIVES

The objective of this study was to investigate oral Candida colonization and candidosis in a group of patients with psoriasis and controls.

STUDY DESIGN

A total of 100 patients with psoriasis and matched controls underwent the concentrated oral rinse test for Candida isolation. Candida species were identified by the VITEK 2 Identification System. Categorical variables were evaluated using the χ(2) test. The median Candida count was compared using the Mann-Whitney U test.

RESULTS

Oral candidiasis was diagnosed in 3% of the patients with psoriasis. The Candida count and prevalence were significantly higher in the patients with psoriasis compared with controls (69% vs 44%, P < .001), but with no relationship to the severity or treatment of psoriasis. Oral Candida was significantly higher in late-onset (at age ≥30 years) compared with early-onset psoriasis (at age <30 years).

CONCLUSIONS

Patients with psoriasis have increased oral Candida colonization and candidiasis. Further studies are needed to clarify the predisposing factor(s) for oral Candida in patients with psoriasis.

Effect of dissolved oxygen concentration (microaerobic and aerobic) on selective enrichment culture for bioaugmentation of acidic industrial wastewater

The successful application of bioaugmentation is largely dependent on the selective enrichment of culture with regards to pH, temperature, salt, or specific toxic organic pollutants. In this study, we investigated the effect of dissolved oxygen (DO) concentrations (aerobic, >2 mg L(-1); microaerobic, <1 mg L(-1)) on yeast enrichment culture for bioaugmentation of acidic industrial wastewater (pH 3.9-4.7). Clone library analyses revealed that the yeast community shifted in response to different DO levels, and that Candida humilis and Candida pseudolambica were individually dominant in the aerobic and microaerobic enrichment cultures. This would significantly influence the isolation results, and further hinder bioaugmentation due to differences in DO environments during the enrichment and application periods. However, differences in the selective enrichment culture cannot be predicted based on differences in pollutant removal performance. Thus, DO concentrations (aerobic/microaerobic) should be considered a secondary selective pressure to achieve successful bioaugmentation.

Calcineurin is required for pseudohyphal growth, virulence, and drug resistance in Candida lusitaniae

Candida lusitaniae is an emerging fungal pathogen that infects immunocompromised patients including HIV/AIDS, cancer, and neonatal pediatric patients. Though less prevalent than other Candida species, C. lusitaniae is unique in its ability to develop resistance to amphotericin B. We investigated the role of the calcium-activated protein phosphatase calcineurin in several virulence attributes of C. lusitaniae including pseudohyphal growth, serum survival, and growth at 37°C. We found that calcineurin and Crz1, a C. albicans Crz1 homolog acting as a downstream target of calcineurin, are required for C. lusitaniae pseudohyphal growth, a process for which the underlying mechanism remains largely unknown in C. lusitaniae but hyphal growth is fundamental to C. albicans virulence. We demonstrate that calcineurin is required for cell wall integrity, ER stress response, optimal growth in serum, virulence in a murine systemic infection model, and antifungal drug tolerance in C. lusitaniae. To further examine the potential of targeting the calcineurin signaling cascade for antifungal drug development, we examined the activity of a calcineurin inhibitor FK506 in combination with caspofungin against echinocandin resistant C. lusitaniae clinical isolates. Broth microdilution and drug disk diffusion assays demonstrate that FK506 has synergistic fungicidal activity with caspofungin against echinocandin resistant isolates. Our findings reveal that pseudohyphal growth is controlled by the calcineurin signaling cascade, and highlight the potential use of calcineurin inhibitors and caspofungin for emerging drug-resistant C. lusitaniae infections.

Inhibition of Candida parapsilosis fatty acid synthase (Fas2) induces mitochondrial cell death in serum

We have recently observed that a fatty acid auxotrophic mutant (fatty acid synthase, Fas2Δ/Δ) of the emerging human pathogenic yeast Candida parapsilosis dies after incubation in various media including serum. In the present study we describe the mechanism for cell death induced by serum and glucose containing media. We show that Fas2Δ/Δ yeast cells are profoundly susceptible to glucose leading us to propose that yeast cells lacking fatty acids exhibit uncontrolled metabolism in response to glucose. We demonstrate that incubation of Fas2Δ/Δ yeast cells with serum leads to cell death, and this process can be prevented with inhibition of protein or DNA synthesis, indicating that newly synthesized cellular components are detrimental to the mutant cells. Furthermore, we have found that cell death is mediated by mitochondria. Suppression of electron transport enzymes using inhibitors such as cyanide or azide prevents ROS overproduction and Fas2Δ/Δ yeast cell death. Additionally, deletion of mitochondrial DNA, which encodes several subunits for enzymes of the electron transport chain, significantly reduces serum-induced Fas2Δ/Δ yeast cell death. Therefore, our results show that serum and glucose media induce Fas2Δ/Δ yeast cell death by triggering unbalanced metabolism, which is regulated by mitochondria. To our knowledge, this is the first study to critically define a link between cytosolic fatty acid synthesis and mitochondrial function in response to serum stress in C. parapsilosis.

Candida parapsilosis is a human opportunistic pathogen associated with significant morbidity and mortality, especially in immunocompromised individuals such as premature, low-birthweight neonates. Our prior studies have indicated that C. parapsilosis effectively utilizes fatty acids/lipids for growth and virulence. We now show that inhibition of the fatty acid synthase (Fas2) results in a hypersensitivity to serum, indicating that yeast cell survival and replication in serum medium or in vivo is dependent on Fas2. Serum hypersensitivity of Fas2-inhibited yeast cells is due to mitochondrial mediated dysregulation of metabolism. Thus, we conclude that Fas2 is candidate antifungal target to combat disseminated fungal infections.

The relation between oral Candida load and bacterial microbiome profiles in Dutch older adults

Currently there are no evidence-based ecological measures for prevention of overgrowth and subsequent infection by fungi in the oral cavity. The aim of this study was to increase our knowledge on fungal-bacterial ecological interactions. Salivary Candida abundance of 82 Dutch adults aged 58-80 years was established relative to the bacterial load by quantitative PCR analysis of the Internal Transcribed (ITS) region (Candida) and 16S rDNA gene (bacteria). The salivary microbiome was assessed using barcoded pyrosequencing of the bacterial hypervariable regions V5-V7 of 16S rDNA. Sequencing data was preprocessed by denoising and chimera removal, clustered in Operational Taxonomic Units (OTUs) and assigned to taxonomy. Both OTU-based (PCA, diversity statistics) and phylogeny-based analyses (UniFrac, PCoA) were performed. Saliva of Dutch older adults contained 0-4 × 10(8) CFU/mL Candida with a median Candida load of 0.06%. With increased Candida load the diversity of the salivary microbiome decreased significantly (p<0.001). Increase in the Candida load correlated positively with class Bacilli, and negatively with class Fusobacteria, Flavobacteria, and Bacteroidia. Microbiomes with high Candida load were less diverse and had a distinct microbial composition towards dominance by saccharolytic and acidogenic bacteria--streptococci. The control of the acidification of the oral environment may be a potential preventive measure for Candida outgrowth that should be evaluated in longitudinal clinical intervention trials.

[Yeast colonization of urinary catheters and the significance of biofilm formation]

OBJECTIVE

Urinary catheters are colonized by a wide range of microorganisms, including numerous yeasts. The catheters are usually colonized by more microbial species forming a community - multispecies biofilm. Catheter colonization usually does not affect the patient's clinical status in any significant way. On the other hand, the biofilm can become a source of endogenous infection and its presence can affect functionality of the catheter and formation of urinary stones. Material a

METHODS

A total of 721 urinary catheters were studied. Microorganisms were released from catheters by sonication and subsequently cultured. Their identification was performed with the use of common phenotypic tests, as well as using MALDI TOF. Yeasts whose identification was ambiguous were recognized by sequencing. Biofilm formation was assessed by growth in a microtiter plate.

RESULTS AND CONCLUSION

Yeast colonization was proved in 244 urinary catheters. However, a total of 274 yeast strains were isolated. Most of them occurred together with other yeast species and/or bacteria on the catheters, producing multispecies biofilm there. The most frequent species was Candida albicans (a total of 144 isolated strains), followed by Candida glabrata (41), Candida tropicalis (41) and Candida parapsilosis sensu stricto (14). Other isolated species were as follows: Candida kefyr (10), Candida krusei (9), Candida fabianii (6), Candida lusitaniae (5), Candida dubliniensis (3) and Saccharomyces cerevisiae (one case). Most of the yeasts rather readily formed a firmly adhering biofilm layer on artificial surfaces.

Evaluation of vulvovaginal symptoms and Candida colonization in women with type 2 diabetes mellitus treated with canagliflozin, a sodium glucose co-transporter 2 inhibitor

BACKGROUND/OBJECTIVE

Women with type 2 diabetes mellitus (T2DM) are at increased risk for vaginal Candida colonization, perhaps because of glucosuria. Sodium glucose co-transporter 2 (SGLT2) inhibitors, in development for the treatment of T2DM, improve glycemic control by increasing urinary glucose excretion. Vaginal Candida colonization and symptomatic vulvovaginal adverse events (VVAE) were assessed in females with T2DM treated with canagliflozin, a SGLT2 inhibitor.

METHODS

In a double-blind study, subjects with T2DM and inadequate glycemic control on metformin were randomized to placebo; canagliflozin 50, 100, 200, 300 mg daily or 300 mg twice daily; or sitagliptin 100 mg daily for 12 weeks. Vaginal swabs for Candida culture were collected from 198 female subjects at baseline and week 12, and during the trial if symptoms consistent with vulvovaginal candidiasis occurred.

RESULTS

At baseline, 23/198 (12%) females had vaginal cultures positive for Candida (C. glabrata: 14; C. albicans: 5; other: 4), with age ≤55 years associated with increased risk (odds ratio [OR], 3.5; 95% confidence interval [CI], 1.1-10.7). Of those with negative cultures at baseline, 31% of canagliflozin and 14% of placebo/sitagliptin subjects converted to positive at week 12 (OR, 2.8; 95% CI, 1.0-7.3 for canagliflozin vs. placebo/sitagliptin). Two placebo/sitagliptin (3%) and 16 canagliflozin subjects (10%) experienced VVAE. Positive vaginal culture for Candida species at baseline was a risk factor for VVAE (OR, 9.1; 95% CI, 2.4-34.0). All 9/9 subjects in the canagliflozin group with a vaginal culture taken at the time of the VVAE were positive for Candida species. Most VVAE were treated with antifungal therapy and resolved without study drug interruption; none led to discontinuation. Study limitations include small population, short duration, and not obtaining cultures in all women with VVAE.

CONCLUSION

Canagliflozin treatment was associated with an increase in vaginal colonization with Candida species and in VVAE in women with T2DM.

Synthesis of 1,2,3-triazole derivatives and in vitro antifungal evaluation on Candida strains

1,2,3-Triazoles have been extensively studied as compounds possessing important biological activities. In this work, we describe the synthesis of ten 2-(1-aryl-1H-1,2,3-triazol-4-yl)propan-2-ols via copper catalyzed azide alkyne cycloaddition (CuAAc or click chemistry). Next thein vitro antifungal activity of these ten compounds was evaluated using the microdilution broth method against 42 isolates of four different Candida species. Among all tested compounds, the halogen substituted triazole 2-[1-(4-chlorophenyl)-1H-(1,2,3)triazol-4-yl]propan-2-ol, revealed the best antifungal profile, showing that further modifications could be done in the structure to obtain a better drug candidate in the future.

[Systemic candidiasis in medical intensive care unit: analysis of risk factors and the contribution of colonization index]

OBJECTIVES

Description of the epidemiological and clinical characteristics of the patients introducing risk factors of invasive candidiasis. Analysis of risk factors for candidiasis invasive and evaluation of the contribution of colonization index (CI) in the diagnosis of the systematic candidiasis in medical intensive care.

PATIENTS AND METHODS

Prospective observational study (October 2007 to October 2009). The selected patients present risk factors of system IC candidiasis with an infectious syndrome or clinical signs suggestive of Candida infection and hospitalized more than 48 hours in medical intensive care unit. Pittet's colonization index was calculated at admission and then once a week added to a blood culture. Patients were classified according to level of evidence of Candida infection and the degree of colonization (CI<0.5, CI ≥ 0.5).

RESULTS

The study included 100 patients. Mean age of our patients was 55.8 ± 18.2 years with male prevalence. Neurological disease was the most frequent pathology in admission (48%). The most common risk factors were broad-spectrum antibiotics and foreign material. In the various mycology IC specimens, Candida albicans was the most frequent, followed by C. tropicalis, then C. glabrata. The CI was greater than or equal to 0.5 at 53% of the patients, and less than 0.5 in 47% of the cases. Among the patients, 15% developed an invasive candidiasis. In multivariate analysis, the corticosteroid therapy was associated with a high colonisation (IC ≥ 0.5) and neutropenia with a high risk of systemic candidiasis. The positive predictive value of CI was 26%. The negative predictive value was 98%, the sensitivity and specificity was 93% and 48% respectively.

CONCLUSION

CI has the advantage to provide a quantified data of the patient's situation in relation to the colonization. But, it isn't helpful with patients having an invasive candidiasis in medical intensive care unit.

Rapid susceptibility testing and microcolony analysis of Candida spp. cultured and imaged on porous aluminum oxide

BACKGROUND

Acquired resistance to antifungal agents now supports the introduction of susceptibility testing for species-drug combinations for which this was previously thought unnecessary. For pathogenic yeasts, conventional phenotypic testing needs at least 24 h. Culture on a porous aluminum oxide (PAO) support combined with microscopy offers a route to more rapid results.

METHODS

Microcolonies of Candida species grown on PAO were stained with the fluorogenic dyes Fun-1 and Calcofluor White and then imaged by fluorescence microscopy. Images were captured by a charge-coupled device camera and processed by publicly available software. By this method, the growth of yeasts could be detected and quantified within 2 h. Microcolony imaging was then used to assess the susceptibility of the yeasts to amphotericin B, anidulafungin and caspofungin (3.5 h culture), and voriconazole and itraconazole (7 h culture).

SIGNIFICANCE

Overall, the results showed good agreement with EUCAST (86.5% agreement; n = 170) and E-test (85.9% agreement; n = 170). The closest agreement to standard tests was found when testing susceptibility to amphotericin B and echinocandins (88.2 to 91.2%) and the least good for the triazoles (79.4 to 82.4%). Furthermore, large datasets on population variation could be rapidly obtained. An analysis of microcolonies revealed subtle effects of antimycotics on resistant strains and below the MIC of sensitive strains, particularly an increase in population heterogeneity and cell density-dependent effects of triazoles. Additionally, the method could be adapted to strain identification via germ tube extension. We suggest PAO culture is a rapid and versatile method that may be usefully adapted to clinical mycology and has research applications.

Prevention of voice prosthesis biofilms: current scenario and future trends in prolonging prosthesis lifetime

Voice rehabilitation after a total laryngectomy is an important requisite for patients' rehabilitation. Oesophageal speech using tracheo-oesophageal-valved prostheses is now considered the state-of-art in postlaryngectomy voice rehabilitation. One of the major drawbacks of voice prostheses is their limited device lifetime. This is due to the deterioration of the silicone rubber material by different bacterial and yeast species, which are organised in the form of a biofilm resulting in internal leakage, increased airflow resistance, impeding speech, respiration and swallowing. The use of antimicrobials though easily applicable is associated with development of resistance if used on long-term basis. Other techniques in the form of modification of physicochemical properties of the silicon surface or covalent binding of antimicrobial agents to the silicon surface have been employed. This article reviews the different strategies investigated until now and the future trends in preventing biofilm formation for prolonging the lifetime of the silicon voice prostheses. Data was collected by conducting a computer aided search of the MED-LINE and PUBMED databases, supplemented by hand searches of key journals. Over 35 articles in the last two decades on the topic have been reviewed out of which 27 were found to be of relevant value for this article.

Stable and non-competitive association of Saccharomyces cerevisiae, Candida milleri and Lactobacillus sanfranciscensis during manufacture of two traditional sourdough baked goods

The microbiota occurring in all the manufacturing phases of two Italian sourdough sweet-leavened baked goods (a typical Genoese dry biscuit, Lagaccio, and a soft stuffed North Italian typical cake, Panettone) were investigated over a period of three years. The two sourdough mother sponges were characterized by the stable presence of three dominant microbial species in potential competition for carbohydrates: Lactobacillus sanfranciscensis, Candida milleri, and Saccharomyces cerevisiae. Genotypic and phenotypic characterizations of microbial isolates pointed out that each mother sponge harbored its own strains, well distinguishable by molecular methods of analysis but not differing in their main metabolic properties from those known for the corresponding species. The microbial and biochemical evolution during the whole production protocol of both manufactures demonstrated that the three microbial species grew at almost the same growth rates, without exhausting any of the main carbon substrates (maltose, glucose and fructose). The quite similar growth dynamics under practical conditions and the constant presence of all fermentable carbohydrates were recognized as responsible for the stable non competitive association of maltose-positive and maltose-negative species in both sourdoughs. However, the two sourdoughs were characterized by quite different LAB to yeast ratio, with values significantly higher in Panettone than in Lagaccio. The cause of this difference could mainly be ascribed to the temperature of the mother sponge regeneration phase, that, in the case of Panettone manufacture, occurred under conditions of moderate refrigeration.

Microbial biofilms on facial prostheses

The composition of microbial biofilms on silicone rubber facial prostheses was investigated and compared with the microbial flora on healthy and prosthesis-covered skin. Scanning electron microscopy showed the presence of mixed bacterial and yeast biofilms on and deterioration of the surface of the prostheses. Microbial culturing confirmed the presence of yeasts and bacteria. Microbial colonization was significantly increased on prosthesis-covered skin compared to healthy skin. Candida spp. were exclusively isolated from prosthesis-covered skin and from prostheses. Biofilms from prostheses showed the least diverse band-profile in denaturing gradient gel electrophoresis (DGGE) whereas prosthesis-covered skin showed the most diverse band-profile. Bacterial diversity exceeded yeast diversity in all samples. It is concluded that occlusion of the skin by prostheses creates a favorable niche for opportunistic pathogens such as Candida spp. and Staphylococcus aureus. Biofilms on healthy skin, skin underneath the prosthesis and on the prosthesis had a comparable composition, but the numbers present differed according to the microorganism.

Modeling of fungal biofilms using a rat central vein catheter

Candida frequently grows as a biofilm, or an adherent community of cells protected from both the host immune system and antimicrobial therapies. Biofilms represent the predominant mode of growth for many clinical infections, including those associated with placement of a medical device. Here, we describe a model for Candida biofilm infection of one important clinical niche, a venous catheter. This animal model system incorporates the anatomical site, immune components, and fluid dynamics of a patient venous catheter infection and can be used for study of biofilm formation, drug resistance, and gene expression.

The Effect of the acetone extract of Arctotis arctotoides (Asteraceae) on the growth and ultrastructure of some opportunistic fungi associated with HIV/AIDS

In this study, the effect of the acetone extract of Arctotis arctotoides (L.f.) O. Hoffm. (Asteraceae) on the growth and ultrastructure of some opportunistic fungi associated with HIV/AIDS was analyzed by means of scanning electron microscope (SEM). Remarkable morphological alterations in the fungal mycelia which were attributed to the loss of cell wall strength ranged from loss of turgidity and uniformity, collapse of entire hyphae to evident destruction of the hyphae. The elements responsible for giving the fungi their characteristic virulence were detected and quantified by energy dispersive X-ray microanalysis techniques. X-ray microanalysis showed the specific spectra of sodium, potassium and sulfur as the principal intersection of the four pathogenic fungi studied. Since these ions have the potential of fostering fungal invasion by altering the permeability of hosts' membranes, their presence was considered inherent to the pathogenicity of the opportunistic fungi. Hence, these findings indicate the potential of the crude extract of A. arctotoides in preventing fungal invasion and subsequent infection of host's membranes.

Two new species of the genus Candida in the Zygoascus clade, Candida lundiana sp. nov. and Candida suthepensis sp. nov., isolated from raw honey in Thailand

During a survey of yeasts associated with raw honey collected in Thailand, two strains of the Zygoascus clade were isolated from the Asian cavity-nesting honeybee Apis cerana and the stingless bee Homotrigona fimbriata. Phylogeny based on 26S rDNA D1/D2 sequences placed these yeasts as members of a clade including Candida bituminiphila, Candida patagonica and Candida polysorbophila. The strains of the two novel species, CBS 12271(T) and CBS 12270(T), respectively, could be unquestionably distinguished from their relatives by rDNA sequences and other taxonomic characteristics. Therefore, the novel anamorphic species, Candida lundiana sp. nov. (type strain CBS 12271(T) = JCM 16823(T)) and Candida suthepensis sp. nov. (type strain CBS 12270(T) = JCM 16822(T)) are described.

[Influence of metal nanoparticles on some microorganisms and microflora of unpasteurized beer]

The influence of nanoparticles of gold, silver, dioxide of cerium and zirconium in low concentration (0.5-7.5 mg/l) on pure cultures of Escherichia coli IEM-1, Bacillus subtilis BT-2, Candida scottii KB-2, Saccharomyces cerevisiae OB-3, Aspergillus niger R-3, Fusarium culmorum T-7 and Penicillium chrysogenum F-7 has been investigated. Silver nanoparticles, which caused a decrease of the amount of S. cerevisiae OB-3 cells by 90% after one hour of exposition, and led to almost complete death of vegetative and spore cells of B. subtilis BT-2 after 1 and 24 h of exposition, respectively, proved to be the most effective antimicrobial preparation. The decrease by one-two orders of the amount of B. subtilis BT-2 and of S cerevisiae OB-3 cells under the influence of preparations of silver nanoparicles in the presence of gold has been established. After adding silver preparations to the unpasteurized beer one could observe a decrease by 10-20% of bacterial and by about 40% of fungi which contaminated microflora on the 20th day of shelf-life. The paper is presented in Ukrainian.

Yeast methylotrophy and autophagy in a methanol-oscillating environment on growing Arabidopsis thaliana leaves

The yeast Candida boidinii capable of growth on methanol proliferates and survives on the leaves of Arabidopsis thaliana. The local methanol concentration at the phyllosphere of growing A. thaliana exhibited daily periodicity, and yeast cells responded by altering both the expression of methanol-inducible genes and peroxisome proliferation. Even under these dynamically changing environmental conditions, yeast cells proliferated 3 to 4 times in 11 days. Among the C1-metabolic enzymes, enzymes in the methanol assimilation pathway, but not formaldehyde dissimilation or anti-oxidizing enzymes, were necessary for yeast proliferation at the phyllosphere. Furthermore, both peroxisome assembly and pexophagy, a selective autophagy pathway that degrades peroxisomes, were necessary for phyllospheric proliferation. Thus, the present study sheds light on the life cycle and physiology of yeast in the natural environment at both the molecular and cellular levels.

Control of postharvest Botrytis fruit rot of strawberry by volatile organic compounds of Candida intermedia

A study was conducted to identify volatile organic compounds or volatiles produced by Candida intermedia strain C410 using gas chromatography-mass spectrometry, and to determine efficacy of the volatiles of C. intermedia in suppression of conidial germination and mycelial growth of Botrytis cinerea and control of Botrytis fruit rot of strawberry. Results showed that, among 49 volatiles (esters, alcohols, alkenes, alkanes, alkynes, organic acids, ketones, and aldehydes) identified from C. intermedia cultures on yeast extract peptone dextrose agar, two compounds, 1,3,5,7-cyclooctatetraene and 3-methyl-1-butanol, were the most abundant. Synthetic chemicals of 1,3,5,7-cyclooctatetraene; 3-methyl-1-butanol; 2-nonanone; pentanoic acid, 4-methyl-, ethyl ester; 3-methyl-1-butanol, acetate; acetic acid, pentyl ester; and hexanoic acid, ethyl ester were highly inhibitory to conidial germination and mycelial growth of B. cinerea. Inhibition of conidial germination and mycelial growth of B. cinerea by volatiles of C. intermedia was also observed. Meanwhile, results showed that incidence and severity of Botrytis fruit rot of strawberry was significantly (P < 0.01) reduced by exposure of the strawberry fruit to the volatiles from C. intermedia cultures or C. intermedia-infested strawberry fruit. These results suggest that the volatiles of C. intermedia C410 are promising biofumigants for control of Botrytis fruit rot of strawberry.

Differentiation between Candida albicans and Candida dubliniensis using hypertonic Sabouraud broth and tobacco agar

INTRODUCTION

Opportunistic fungal infections in immunocompromised hosts are caused by Candida species, and the majority of such infections are due to Candida albicans. However, the emerging pathogen Candida dubliniensis demonstrates several phenotypic characteristics in common with C. albicans, such as production of germ tubes and chlamydospores, calling attention to the development of stable resistance to fluconazole in vitro. The aim of this study was to evaluate the performance of biochemistry identification in the differentiating between C. albicans and C. dubliniensis, by phenotyping of yeast identified as C. albicans.

METHODS

Seventy-nine isolates identified as C. albicans by the API system ID 32C were grown on Sabouraud dextrose agar at 30°C for 24-48h and then inoculated on hypertonic Sabouraud broth and tobacco agar.

RESULTS

Our results showed that 17 (21.5%) isolates were growth-inhibited on hypertonic Sabouraud broth, a phenotypic trait inconsistent with C. albicans in this medium. However, the results observed on tobacco agar showed that only 9 (11.4%) of the growth-inhibited isolates produced characteristic colonies of C. dubliniensis (rough colonies, yellowish-brown with abundant fragments of hyphae and chlamydospores).

CONCLUSIONS

The results suggest that this method is a simple tool for screening C. albicans and non-albicans yeast and for verification of automated identification.

Calcineurin controls drug tolerance, hyphal growth, and virulence in Candida dubliniensis

Candida dubliniensis is an emerging pathogenic yeast species closely related to Candida albicans and frequently found colonizing or infecting the oral cavities of HIV/AIDS patients. Drug resistance during C. dubliniensis infection is common and constitutes a significant therapeutic challenge. The calcineurin inhibitor FK506 exhibits synergistic fungicidal activity with azoles or echinocandins in the fungal pathogens C. albicans, Cryptococcus neoformans, and Aspergillus fumigatus. In this study, we show that calcineurin is required for cell wall integrity and wild-type tolerance of C. dubliniensis to azoles and echinocandins; hence, these drugs are candidates for combination therapy with calcineurin inhibitors. In contrast to C. albicans, in which the roles of calcineurin and Crz1 in hyphal growth are unclear, here we show that calcineurin and Crz1 play a clearly demonstrable role in hyphal growth in response to nutrient limitation in C. dubliniensis. We further demonstrate that thigmotropism is controlled by Crz1, but not calcineurin, in C. dubliniensis. Similar to C. albicans, C. dubliniensis calcineurin enhances survival in serum. C. dubliniensis calcineurin and crz1/crz1 mutants exhibit attenuated virulence in a murine systemic infection model, likely attributable to defects in cell wall integrity, hyphal growth, and serum survival. Furthermore, we show that C. dubliniensis calcineurin mutants are unable to establish murine ocular infection or form biofilms in a rat denture model. That calcineurin is required for drug tolerance and virulence makes fungus-specific calcineurin inhibitors attractive candidates for combination therapy with azoles or echinocandins against emerging C. dubliniensis infections.

Economic optimized medium for tensio-active agent production by Candida sphaerica UCP0995 and application in the removal of hydrophobic contaminant from sand

Statistical experimental designs and response surface methodology were employed to optimize the concentrations of agroindustrial residues as soybean oil (SORR) from refinery, and corn steep liquor (CSL) from corn industry, for tensio-active agent produced by Candida sphaerica UCP 0995. Three 2(2) full factorial design were applied sequentially to investigate the effects of the concentrations and interactions of soybean oil refinery residue and corn steep liquor on the surface tension of free-cell culture broth for 144 h. Two 2(2) central composite designs and response surface methodology were adopted to derive a statistical model to measure the effect of SORR and CSL on the surface tension of the free-cell culture broth for 144 h. The regression equation obtained from the experimental data using a central composite design was solved, and by analyzing the response surface contour plots, the optimal concentrations of the constituents of the medium were determined: 8.63% v/v (≅9% v/v) of SORR and 8.80% v/v (≅9% v/v) CSL. The minimum surface tension predicted and experimentally confirmed was 25.25 mN/m. The new biosurfactant, denominated Lunasan, recovered 95% of motor oil adsorbed in a sand sample, thus showing great potential for use in bioremediation processes, especially in the petroleum industry.

[Evaluation of the significance of molecular methods in the diagnosis of invasive fungal infections: comparison with conventional methods]

Direct microscopy and culture methods are still valuable standard conventional methods for the diagnosis of infections caused by true or opportunistic fungal pathogens, especially in high risk patients. However, some of the problems concerning the application and interpretation of those methods, indicate a need for more rapid, practical and reliable tests with high sensitivity and specificity. This study was conducted to compare the results obtained by molecular methods with the results of conventional methods performed simultaneously for the detection and identification of causative fungi in clinical samples. Clinical samples [24 bronchoalveolar lavage (BAL); 14 blood; 5 peritoneal, 4 pleural and 1 pericardial fluids; 1 cerebrospinal fluid (CSF), 1 urine] from 50 immunosuppressed patients were included in the study. All of the samples were cultivated on Sabouraud dextrose and brain-heart infusion agar media and incubated at 30°C and 37°C for 30 days. Samples other than blood were stained with 10-15% KOH + calcofluor white and examined by direct microscopy. Conventional identification of the isolates were performed by using basic morphological and biochemical characteristics. The isolation of fungal DNAs for polymerase chain reaction (PCR) was achieved by classical phenol-chloroform-isoamylalcohol procedure (9-10 hours) and commercial DNA extraction kit (6-7 hours) and general and species-specific primers (multiplex) from ITS1, ITS2, ITS3, ITS4, 5.8S rDNA and 28S rDNA regions were chosen for amplification. In PCR results, 550 base-paired (bp) bands obtained with universal primers were evaluated as fungal DNA positivity, and 273 bp, 320 bp, 423 bp, 357 bp, 136 bp and 385 bp bands with species-specific primers were evaluated as Candida albicans, Candida parapsilosis, Candida glabrata, Candida tropicalis, Cryptococcus neoformans and Aspergillus fumigatus positivities, respectively. Seventeen (34%) of the 50 samples yielded fungal growth on culture (C.albicans in 12 BAL, 3 blood, 1 urine sample, and C.parapsilosis in 1 urine), while seven BAL out of 36 (19.4%) non-blood samples gave positive result by direct microscopy. Of the samples 27 (54%) were found positive by PCR. All of the 17 culture positive samples were also found PCR positive, and all of the 23 culture negative samples were also found PCR negative. However, fungal DNAs were detected by PCR in 10 of the samples (5 BAL, 4 peritoneal fluids, 1 CSF) which were negative by direct microscopy and culture methods. These fungi were identified as C.albicans (n= 8), C.parapsilosis (n= 1, from peritonal fluid) and C.neoformans (n= 1, from CSF) by multiplex PCR. No samples yielded PCR negative, culture positive result. All of those 10 PCR positive, culture negative samples belonged to patients who were under antifungal treatment. The detection of C.neoformans DNA from CSF sample of a patient with suspected cryptococcosis only with PCR provided the chance for rapid therapy. In statistical evaluation, the concordance between culture and PCR methods were found significantly high (k= 0.61; p< 0.001), whereas it was minimal (k= 0.24; p< 0.001) between direct microscopy and PCR. When considering culture as the reference method, the sensitivity and specificity of PCR were estimated as 100% and 69.7%, respectively. In addition, multiplex PCR was as successful as culture and conventional identification methods in the identification of all fungal species. As a result, without disregarding conventional methods, use of PCR might be recommended for the identification of fungal species on the basis of clinical status of the patient and conditions of the laboratory.

Optimizing a Candida biofilm microtiter plate model for measurement of antifungal susceptibility by tetrazolium salt assay

Candida spp. infect medical devices, such as venous and urinary catheters, by adhering to the surface and forming a community of drug-resistant cells surrounded by a matrix. The ability to measure drug activity during this biofilm mode of growth is of interest for the investigation of resistance mechanisms and novel antifungal therapies. The tetrazolium salt (XTT) reduction assay is the test most commonly used to estimate viable biofilm growth and to examine the impact of biofilm therapies. The primary goal of the current experiments was to identify assay variables that affect the XTT assay result in order to improve assay reproducibility, sensitivity, and throughput for the study of antifungal activity. The species used in the current studies included Candida albicans, C. parapsilosis, and C. glabrata. The assay variables that were studied included the impact of culture conditions, the duration of biofilm growth, the timing and frequency of drug administration, the XTT source and concentration, and the duration of XTT incubation. The conditions that impacted the assay readout and altered assay sensitivity included the duration of biofilm growth, the frequency of drug dosing, and the duration of XTT incubation. Several factors were found to reduce time and assay expense, including the elimination of washing steps, the shortening of incubation times, and the use of lower XTT concentrations. A description of assay pitfalls and troubleshooting is included. Recognition of these technical variables should allow investigators to better design reproducible biofilm therapeutic studies.

Characteristics of growth of yeasts and yeast-like fungi on chromogenic medium CHROMagar andida (GRASO)

Early detection and correct diagnosis of fungal infection is important for further therapy and prophylaxis. Currently, there are a number of proposals related to rapid diagnostic tests. To those we can include chromogenic media, such as CHROMagar Candida (GRASO). This medium has been developed to differentiate four species of genus Candida. Its use in laboratory has opened up possibilities for growing not only the genus Candida, but also other fungi. The study suggests that medium CHROMagar Candida can provide an excellent pre-test, or be used as complementary to biochemical tests. Establishing a full template of colours would enable more efficient and fuller use of the medium properties, especially in the discrimination of the teleomorphic form from anamorphic.

[Modern antifungals in therapy of nosocomial mycosis in oncologic patients]

Rational position of voriconazole in the treatment of oncologic inpatients was shown and the criteria of its use in the algorithms of the therapy and prophylaxis of nosocomial fungal infections were developed. The clinical trial enrolled 50 patients with oncologic pathologies. The patients were divided into two groups of possible invasive candidiasis risk. The patients of one group were treated with fluconazole (Diflucan) and those of the other group were treated with voriconazole (Vifend). The spectrum of the hospital fungal flora was determined and susceptibility of 310 clinically important opportunistic fungi was investigated. All the isolates of Candida albicans and C.tropicalis were susceptible to amphotericin B, fluconazole and voriconazole and 79 and 50% of the isolates were susceptible to intraconazole respectively. As for the C.krusei isolates, 67% was susceptible to amphotericin B, 50% was susceptible to fluconazole, 100% was susceptible to voriconazole and none of the strains was susceptible to intraconazole. By the clinical efficacy voriconazole was superior to fluconazole and comparable with amphotericin B, while superior to it by the number of the side effects and by the cost of the treatment course. It was concluded that voriconazole should be considered as the main agent in the antifungal therapy of oncologic patients.

Using the residue of spirit production and bio-ethanol for protein production by yeasts

The residue (vinasse) formed during the distillation of bio-ethanol and cachaça, a traditional rum-type spirit produced from sugar-cane in Brazil, is highly harmful if discharged into the environment due to high values of COD and BOD. One possibility for minimizing the impact of vinasse in soils and waters is to use the residue in the production of microbial biomass for use as an animal feed supplement that will provide high levels on nitrogen (>9% d.m.) and low content of nucleic (≤ 10% d.m.) This paper reports the production and quality of biomass produced from fermentation of Saccharomyces cerevisiae and Candida parapsilosis in culture media under 12 different culture conditions and the respective effects of each variable (glucose, yeast extract, peptone, potassium phosphate, vinasse, pH and temperature). Of the S. cerevisiae isolates tested, two (VR1 and PE2) originating from fuel alcohol-producing plants were identified as offering the best potential for the industrial production of single cell protein from vinasse due to highest biomass productivity. Our results showed a potential viable and economic use of vinasse.

Influence of fenamidone, indoxacarb, pyraclostrobin, and deltamethrin on the population of natural yeast microflora during winemaking of two sardinian grape cultivars

The influence of fenamidone ((S)-1-anilino-4-methyl-2-methylthio-4-phenylimidazolin-5-one), pyraclostrobin (methyl 2-[1-(4-chlorophenyl)pyrazol-3-yloxymethyl]-N-methoxycarbanilate), indoxacarb (methyl 7-Chloro-2,5-dihydro-2-[[(methoxycarbonyl) [4- (trifluoromethoxy) phenyl] amino] carbonyl] indeno[1,2-e][1,3,4] oxadiazine-4a(3H)-carboxylate), and deltamethrin ([cyano-[3-(phenoxy)phenyl]methyl] 3-(2,2-dibromoethenyl)-2,2-dimethylcyclopropane-1-carboxylate) on spontaneous fermentation carried out by natural yeast grapes microflora, was studied during the wine-making process. Aliquots of pesticide standard solutions were added to the grapes before crushing, to reach a concentration equal or half the maximum residue limit (MRL). Vinifications were performed, with maceration (R), or without maceration (W). During the wine-making process, samples were taken at the beginning (one hour after grapes crushing), at the middle and at the end of the spontaneous fermentation process. At half the MRL concentration, deltamethrin affected Pichia sp. population with a decrease of almost 50 %, while fenamidone decreased Candida sp., Candida stellata at 83, and 36%, respectively. Metschnikowia pulcherrima population decreased in all samples when compared to the control. Experiments at MRL levels showed a strong reduction for all non-Saccharomyces yeast species, when grapes had been treated with pyraclostrobin, fenamidone, and deltamethrine, except for Candida sp. which was found to have been affected only by fenamidone residues. Growth zone inhibition test showed only an in vitro activity of pyraclostrobin over Kloeckera spp., C. stellata, and M. pulcherrima. Microvinification experiments produced wines with no differences concerning S. cerevisiae population as well as production of ethanol and residual sugars. Experiments showed that at the end of the fermentation process pesticides were adsorbed by the lees and grape skins, and no pesticides residue was detectable in wine.

Soybean toxin (SBTX), a protein from soybeans that inhibits the life cycle of plant and human pathogenic fungi

Soybean toxin (SBTX) is a 44 kDa glycoprotein that is lethal to mice (LD(50) = 5.6 mg/kg). This study reports the toxicity of SBTX on pathogenic fungi and yeasts and the mechanism of its action. SBTX inhibited spore germination of Aspergillus niger and Penicillium herguei and was toxic to Candida albicans, Candida parapsilosis, Kluyveromyces marxiannus , Pichia membranifaciens, and Saccharomyces cerevisiae. In addition, SBTX hampered the growth of C. albicans and K. marxiannus and inhibited the glucose-stimulated acidification of the incubation medium by S. cerevisiae, suggesting that SBTX interferes with intracellular proton transport to the external medium. Moreover, SBTX caused cell-wall disruption, condensation/shrinkage of cytosol, pseudohyphae formation, and P. membranifaciens and C. parapsilosis cell death. SBTX is toxic to fungi at concentrations far below the dose lethal to mice and has potential in the design of new antifungal drugs or in the development of transgenic crops resistant to pathogens.

Effect of marine polyunsaturated fatty acids on biofilm formation of Candida albicans and Candida dubliniensis

The effect of marine polyunsaturated fatty acids on biofilm formation by the human pathogens Candida albicans and Candida dubliniensis was investigated. It was found that stearidonic acid (18:4 n-3), eicosapentaenoic acid (20:5 n-3), docosapentaenoic acid (22:5 n-3) and docosahexaenoic acid (22:6 n-3) have an inhibitory effect on mitochondrial metabolism of both C. albicans and C. dubliniensis and that the production of biofilm biomass by C. dubliniensis was more susceptible to these fatty acids than C. albicans. Ultrastructural differences, which may be due to increased oxidative stress, were observed between treated and untreated cells of C. albicans and C. dubliniensis with formation of rough cell walls by both species and fibrillar structures in C. dubliniensis. These results indicate that marine polyunsaturated fatty acids may be useful in the treatment and/or prevention of biofilms formed by these pathogenic yeasts.

[Morphotyping, genotyping and investigation of some virulence factors in different morphotypes of Candida parapsilosis clinical isolates]

In recent years there is an increase in frequency of systemic candidiasis cases caused by Candida parapsilosis. However there isn't any standardized genotyping method to be used in epidemiology of those infections. In this study we aimed to determine utility of morphotyping instead of genotyping to study the epidemiology of 53 C.parapsilosis strains isolated from blood (n= 40) and urine (n= 13) cultures of inpatients at Marmara University Hospital, Istanbul, Turkey. The isolates were morphotyped according to their surface and color properties on Sabouraud-triphenyltetrazolium agar (STTZ) and surface characteristics on malt extract agar (MA) media and 10 different subgroups were obtained. In order to genotype the strains, RAPD-PCR (Random Amplified Polymorphic DNA-Polymerase Chain Reaction) method was used and three different genotypes were obtained comprising mostly type II (90.6%). One of the putative virulence factors investigated in the isolates was phospholipase activity. Phospholipase production was not detected in any of the strains on egg-yolk agar (pH: 4.2). Esterase activity of the strains on Tween-80 agar was negative except for one. In order to observe acid proteinase activity, bovine serum albumin containing (pH: 5.0) agar was used and in 11.3% of the strains no acid proteinase activity was seen while in 75.5% moderate (+), in 13.2% strong (++) activity was detected. Slime production was investigated in 8% glucose containing Sabouraud broth (SB) medium and 67.9 % of the strains were found to be negative; while 20.7% were weakly (+), 7.5% were moderately (++) and 3.7% were strongly (+++) positive. Hydrophobicity of the strains was evaluated by using hexadecane hydrocarbon adherence assay and one isolate was weakly hydrophobic while the remaining strains were found to be moderately hydrophobic. We could not observe superiority of morphotyping over genotyping. Additionally no property was found to associate with a certain morphotype, in terms of virulence factors.

Bacterial lipopolysaccharides variably modulate in vitro biofilm formation of Candida species

The objective of this study was to evaluate the effect of the bacterial endotoxin LPS on Candida biofilm formation in vitro. The effect of the LPS of Pseudomonas aeruginosa, Klebsiella pneumoniae, Serratia marcescens and Salmonella typhimurium on six different species of Candida, comprising Candida albicans ATCC 90028, Candida glabrata ATCC 90030, Candida krusei ATCC 6258, Candida tropicalis ATCC 13803, Candida parapsilosis ATCC 22019 and Candida dubliniensis MYA 646, was studied using a standard biofilm assay. The metabolic activity of in vitro Candida biofilms treated with LPS at 90 min, 24 h and 48 h was quantified by XTT reduction assay. Viable biofilm-forming cells were qualitatively analysed using confocal laser scanning microscopy (CLSM), while scanning electron microscopy (SEM) was employed to visualize the biofilm structure. Initially, adhesion of C. albicans was significantly stimulated by Pseudomonas and Klebsiella LPS. A significant inhibition of Candida adhesion was noted for the following combinations: C. glabrata with Pseudomonas LPS, C. tropicalis with Serratia LPS, and C. glabrata, C. parapsilosis or C. dubliniensis with Salmonella LPS (P<0.05). After 24 h of incubation, a significant stimulation of initial colonization was noted for the following combinations: C. albicans/C. glabrata with Klebsiella LPS, C. glabrata/C. tropicalis/C. krusei with Salmonella LPS. In contrast, a significant inhibition of biofilm formation was observed in C. glabrata/C. dubliniensis/C. krusei with Pseudomonas LPS, C. krusei with Serratia LPS, C. dubliniensis with Klebsiella LPS and C. parapsilosis/C. dubliniensis /C. krusei with Salmonella LPS (P<0.05). On further incubation for 48 h, a significant enhancement of biofilm maturation was noted for the following combinations: C. glabrata/C. tropicalis with Serratia LPS, C. dubliniensis with Klebsiella LPS and C. glabrata with Salmonella LPS, and a significant retardation was noted for C. parapsilosis/C. dubliniensis/C. krusei with Pseudomonas LPS, C. tropicalis with Serratia LPS, C. glabrata/C. parapsilosis/C. dubliniensis with Klebsiella LPS and C. dubliniensis with Salmonella LPS (P<0.05). These findings were confirmed by SEM and CLSM analyses. In general, the inhibition of the biofilm development of LPS-treated Candida spp. was accompanied by a scanty architecture with a reduced numbers of cells compared with the profuse and densely colonized control biofilms. These data are indicative that bacterial LPSs modulate in vitro Candida biofilm formation in a species-specific and time-dependent manner. The clinical and the biological relevance of these findings have yet to be explored.

[Presumptive identification of Candida spp. and other clinically important yeasts: usefulness of Brilliance Candida Agar]

Fungal infections caused by yeasts have increased during the last decades and invasive forms represent a serious problem for human health. Candida albicans is the species most frequently isolated from clinical samples. However, other emerging yeast pathogens are increasingly responsible for mycotic infections, and some of them are resistant to some antifungal drugs. Consequently, it is necessary to have methods that can provide a rapid presumptive identification at species level. Numerous chromogenic agar media have been shown to be of value as diagnostic tools. We have compared a chromogenic medium, Brilliance Candida Agar, with CHROMagar Candida, the chromogenic medium most used in our country. A multicentre study was conducted in 16 Hospitals belonging to the Mycology Net of Buenos Aires City Government. A total of 240 yeast isolates were included in this research. The new chromogenic agar showed results very similar to those obtained with CHROMagar Candida.