Production of 2-phenethyl alcohol and 2-phenyllactic acid in Candida species

2-Phenethyl alcohol (2-PEA) and 2-phenyllactic acid (2-PLA) were isolated from the culture filtrates of Candida species grown in media containing peptone or phenylalanine as nitrogen source. These compounds were characterized by comparing their UV, IR, and NMR spectral properties with authentic samples. Candida species differed markedly in their production of 2-PEA and 2-PLA. Experiments using [14C]-phenylalanine indicated that both 2-PEA and 2-PLA are synthesised from L-phenylalanine. A pathway for the biosynthesis of 2-PEA from L-phenylalanine has been proposed.

Stable hybrid containing haploid genomes of two obligate diploid Candida species

Candida albicans and Candida dubliniensis are diploid, predominantly asexual human-pathogenic yeasts. In this study, we constructed tetraploid (4n) strains of C. albicans of the same or different lineages by spheroplast fusion. Induction of chromosome loss in the tetraploid C. albicans generated diploid or near-diploid progeny strains but did not produce any haploid progeny. We also constructed stable heterotetraploid somatic hybrid strains (2n + 2n) of C. albicans and C. dubliniensis by spheroplast fusion. Heterodiploid (n + n) progeny hybrids were obtained after inducing chromosome loss in a stable heterotetraploid hybrid. To identify a subset of hybrid heterodiploid progeny strains carrying at least one copy of all chromosomes of both species, unique centromere sequences of various chromosomes of each species were used as markers in PCR analysis. The reduction of chromosome content was confirmed by a comparative genome hybridization (CGH) assay. The hybrid strains were found to be stably propagated. Chromatin immunoprecipitation (ChIP) assays with antibodies against centromere-specific histones (C. albicans Cse4/C. dubliniensis Cse4) revealed that the centromere identity of chromosomes of each species is maintained in the hybrid genomes of the heterotetraploid and heterodiploid strains. Thus, our results suggest that the diploid genome content is not obligatory for the survival of either C. albicans or C. dubliniensis. In keeping with the recent discovery of the existence of haploid C. albicans strains, the heterodiploid strains of our study can be excellent tools for further species-specific genome elimination, yielding true haploid progeny of C. albicans or C. dubliniensis in future.

Prior colonisation with Candida species fails to guide empirical therapy for candidaemia in critically ill adults

Objectives Pre-emptive fluconazole (fcz) anti-fungal therapy is often based upon Candida colonisation of at least 2 non-contiguous non-sterile sites. The aim of this study was to evaluate the relationship between candidaemia and prior colonisation of non-sterile sites. Methods A retrospective observational study was performed in the intensive care unit/high dependency unit (ICU/HDU) of a University hospital on alternate years from 1999–2007, where a pre-emptive anti-fungal therapy policy was introduced in 2005. Results A higher proportion of blood isolates were Candida glabrata compared with non-sterile isolates (16/46 vs 106/1062; p

Use of the DNA Checkerboard hybridization method for detection and quantitation of Candida species in oral microbiota

The DNA Checkerboard method enables the simultaneous identification of distinct microorganisms in a large number of samples and employs up to 45 whole genomic DNA probes to gram-negative and gram-positive bacterial species present in subgingival biofilms. Collectively, they account for 55%-60% of the bacteria in subgingival biofilms. In this study, we present the DNA Checkerboard hybridization as an alternative method for the detection and quantitation of Candida species in oral cavities. Our results reveal that DNA Checkerboard is sensitive enough and constitutes a powerful and appropriate method for detecting and quantifying Candida species found in the oral cavity.

Oral colonization by Candida species in AIDS pediatric patients

The aim of this study was to assess the prevalence of factors associated with oral colonization by Candida spp. in pediatric patients with AIDS. The sample comprised of 117 children. Clinical status, medicines in use, and laboratory findings were obtained from hospital records; sociodemographic data were given by relatives. A dental examination assessed the prevalence of dental caries. The prevalence of oral colonization by Candida was 62%. Only seven children presented clinical manifestation of oral candidosis despite their high viral load index and low-for-age CD4 count. Candida colonization was directly associated with frequent use of antibiotics (prevalence ratio [PR] = 1.44), sulfa drugs (PR = 1.23), alteration in the oral mucosa (PR = 1.55), and untreated dental caries (PR = 1.93). It was inversely associated with the use of antiretroviral therapies (PR = 0.65). Candida albicans was the most frequently detected species (80%); phenotypic tests did not detect C. dubliniensis strains. This study observed a low prevalence of Candida-related oral lesions in these patients, which is compatible with the hypothesis that antiretroviral medicines may have contributed to reducing oral manifestations from Candida infection. The high prevalence of Candida colonization in HIV+/AIDS children with untreated dental caries reinforces the importance of oral health care in interdisciplinary health units that assist these patients.

Correlation Between Etest (R), Disk Diffusion, and Microdilution Methods for Antifungal Susceptibility Testing of Candida Species From Infection and Colonization

The correlation between the microdilution (MD), Etest (R) (ET), and disk diffusion (DD) methods was determined for amphotericin B, itraconazole and fluconazole. The minimal inhibitory concentration (MIC) of those antifungal agents was established for a total of 70 Candida spp. isolates from colonization and infection. The species distribution was: Candida albicans (n = 27), C. tropicalis (n = 17), C. glabrata (n = 16), C. parapsilosis (n = 8), and C. lusitaniae (n = 2). Non-Candida albicans Candida species showed higher MICs for the three antifungal agents when compared with C. albicans isolates. The overall concordance (based on the MIC value obtained within two dilutions) between the ET and the MD method was 83% for amphotericin B, 63% for itraconazole, and 64% for fluconazole. Considering the breakpoint, the agreement between the DD and MD methods was 71% for itraconazole and 67% for fluconazole. The DD zone diameters are highly reproducible and correlate well with the MD method, making agar-based methods a viable alternative to MD for susceptibility testing. However, data on agar-based tests for itraconazole and amphotericin B are yet scarce. Thus, further research must still be carded out to ensure the standardization to other antifungal agents. J. Clin. Lab. Anal. 23:324-330, 2009. (C) 2009 Wiley-Liss, Inc.

Antifungal activity of tri- and tetra-thioureido amino derivatives against different Candida species

The in vitro antifungal activity of six thioureido substituted amines (P1-P6) was evaluated against Candida species, including Candida albicans, C. glabrata, C. krusei and C. parapsilosis. These tri- and tetra-thioureido amino derivatives with different methylation levels were synthesised through easy synthetic routes to evaluate their antifungal properties against Candida species. Among all studied derivatives, the tri-(2-thioureido-ethyl)-amine (P1) was the most active compound inhibiting C. albicans and C. glabrata at a concentration of 0.49 mu g ml(-1); P3, the N,N `,N ``,N ```-hexamethyl-derivative, also showed inhibitory activity against C. albicans and C. glabrata, but in higher concentrations (250 mu g ml(-1)). The N,N `,N ``,N ```-tetramethylated amine (P5) only inhibited the growth of C. glabrata, but its corresponding N,N `,N ``,N ```-octamethyl derivative (P6) was also active against C. glabrata (125 mu g ml(-1)) and it was the only compound active against C. parapsilosis. P2 and P4 showed no significant antifungal activity. The structure-activity relationship of the thioureido-substituted derivatives indicates that the molecular branching and the alkylation levels can influence the antifungal activity. This study demonstrated that thioureido derivatives exhibited significant antifungal activity against Candida species and that they can be considered as a very promising bioactive lead compound to develop novel antifungal agents.

Growth inhibition of Candida species and Aspergillus fumigatus by statins

Statins are a class of drugs widely used for lowering high cholesterol levels through their action on 3-hydroxy-3-methylglutaryl-CoA reductase, a key enzyme in the synthesis of cholesterol. We studied the effects of two major statins, simvastatin and atorvastatin, on five Candida species and Aspergillus fumigatus. The statins strongly inhibited the growth of all species, except Candida krusei. Supplementation of Candida albicans and A. fumigatus with ergosterol or cholesterol in aerobic culture led to substantial recovery from the inhibition by statins, suggesting specificity of statins for the mevalonate synthesis pathway. Our findings suggest that the statins could have utility as antifungal agents and that fungal colonization could be affected in those on statin therapy.

Novel endoperoxides: synthesis and activity against Candida species

Fifteen new endoperoxides have been synthesised and tested for activity against pathogenic Candida species. These endoperoxides can be prepared in high yields, in one to three steps, from inexpensive starting materials. Despite chemical and structural similarities, their inhibitory activity against Candida growth varied greatly from one endoperoxide to another, and one species to another. This study of susceptibility to endoperoxide compounds presented here may lead to the development of potent new antifungal agents.

Growth of Candida species on complete dentures: effect of microwave disinfection

Microwave disinfection of complete dentures has been recommended to treat denture stomatitis in non-immune compromised patients. Oral candidiasis is a frequent manifestation of HIV infection. The objective of this study is to evaluate the effectiveness of microwave irradiation on the disinfection of complete dentures inoculated with American Type Culture Collection (ATCC) and HIV isolates of five species of Candida. Fifty dentures were made, sterilised and inoculated with the tested microorganisms (C. albicans, C. dubliniensis, C. krusei, C. glabrata and C. tropicalis). After incubation (37 degrees C/48 h), dentures were microwaved (650 W/3 min). Non-irradiated dentures were used as positive controls. Replicate aliquots of suspensions were plated at dilutions 10(-1) to 10(-4) and incubated (37 degrees C/48 h). Colony counts (cfu ml(-1)) were quantified. Dentures were also incubated at 37 degrees C for 7 days. Data were analysed with 2-way anova and Tukey HSD tests (alpha = 0.05). Dentures contaminated with all Candida species showed sterilisation after microwave irradiation. All control dentures showed microbial growth on the plates. The cfu ml(-1) for C. glabrata was higher than those of C. albicans, C. dubliniensis and C. tropicalis whereas the cfu ml(-1) for C. krusei was lower. The cfu ml(-1) for clinical isolates was higher than those of ATCC yeast. Microwave irradiation for 3 min at 650 W resulted in sterilisation of all complete dentures.

Photodynamic inactivation of four Candida species induced by photogem®

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Oral distribution of Candida species and presence of oral lesions in Brazilian leprosy patients under multidrug therapy

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Catalase activity of different Candida species after exposition to specific antiserum

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Electrophoretic variants of intracellular catalase of different Candida species

Intracellular and extracellular catalases of different species of Candida were investigated using different culture media. All the Candida strains produced intracellular catalase, whose enzymatic activity was detected by non-denaturating polyacrylamide gradient (4-30%) gel electrophoresis. The cell extracts presented a major 230 kDa catalase band and in some strains variants of catalase with different molecular weights were detected. Candida catalase activity was not affected by heating at 50degreesC and incubation with beta-mercaptoethanol, but treatment with sodium dodecyl sulphate inhibited or reduced enzymatic activity. Extracellular enzyme activity was not detected in any of the culture filtrate extracts tested.

Studies on hyaluronidase, chondroitin sulphatase, proteinase and phospholipase secreted by Candida species

We studied the ability of different Candida species to produce,at the same time, hyaluronidase, chondroitin sulphatase, proteinase, and phospholipase to assess whether they could be related to Candida pathogenicity. Only C. albicans was able to produce the four enzymes tested (73%) and was highly virulent to mice. Strains, that lack the capacity to produce one or more of the enzymes assayed, seemed less virulent or avirulent, similarly to the spontaneous hyaluronidase, chondroitin sulphatase, phospholipase and proteinase-deficient C. albicans strain FCF 14, 1 which was non-pathogenic to mice. Among the other Candida species tested, none of them produced the four enzymes simultaneously, being less virulent in intravenously inoculated mice.