Kodamaea nitidulidarum, Candida restingae and Kodamaea anthophila, three new related yeast species from ephemeral flowers.
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Three new yeast species were discovered during studies of yeasts associated with ephemeral flowers in Brazil, Australia and Hawaii. Their physiological and morphological similarity to Kodamaea (Pichia) ohmeri suggested a possible relationship to that species, which was confirmed by rDNA sequencing. Kodamaea nitidulidarum and Candida restingae were found in cactus flowers and associated nitidulid beetles in sand dune ecosystems (restinga) of South-eastern Brazil. Over 350 strains of Kodamaea anthophila were isolated from Hibiscus and morning glory flowers (Ipomoea spp.) in Australia, and from associated nitidulid beetles and Drosophila hibisci. A single isolate came from a beach morning glory in Hawaii. Expansion of the genus Kodamaea to three species modified the existing definition of the genus only slightly. The type and isotype strains are as follows: K. nitidulidarum strains UFMG96-272T (h+; CBS 8491T) and UFMG96-394I (h-; CBS 8492I); Candida restingae UFMG96-276T (CBS 8493T); K. anthophila strains UWO(PS)95-602.1T (h+; CBS 8494T), UWO(PS)91-893.2I (h-; CBS 8495I) and UWO(PS)95-725.1I (h-; CBS 8496I). (+info)
BE-31405, a new antifungal antibiotic produced by Penicillium minioluteum. I. Description of producing organism, fermentation, isolation, physico-chemical and biological properties.
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A new antifungal antibiotic, BE-31405, was isolated from the culture broth of a fungal strain, Penicillium minioluteum F31405. BE-31405 was isolated by adsorption on high porous polymer resin (Diaion HP-20), followed by solvent extraction, precipitation and crystallization. BE-31405 showed potent growth inhibitory activity against pathogenic fungal strains such as Candida albicans, Candida glabrata and Cryptococcus neoformans, but did not show cytotoxic activity against mammalian cells such as P388 mouse leukemia. The mechanism studies indicated that BE-31405 inhibited the protein synthesis of C. albicans but not of mammalian cells. (+info)
Amphotericin B- and fluconazole-resistant Candida spp., Aspergillus fumigatus, and other newly emerging pathogenic fungi are susceptible to basic antifungal peptides.
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The present study shows that a number of basic antifungal peptides, including human salivary histatin 5, a designed histatin analog designated dhvar4, and a peptide from frog skin, PGLa, are active against amphotericin B-resistant Candida albicans, Candida krusei, and Aspergillus fumigatus strains and against a fluconazole-resistant Candida glabrata isolate. (+info)
Efficient homologous and illegitimate recombination in the opportunistic yeast pathogen Candida glabrata.
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The opportunistic pathogen Candida glabrata causes significant disease in humans. To develop genetic tools to investigate the pathogenicity of this organism, we have constructed ura3 and his3 auxotrophic strains by deleting the relevant coding regions in a C. glabrata clinical isolate. Linearized plasmids carrying a Saccharomyces cerevisiae URA3 gene efficiently transformed the ura3 auxotroph to prototrophy. Homologous recombination events were observed when the linearized plasmid carried short terminal regions homologous with the chromosome. In contrast, in the absence of any chromosomal homology, the plasmid integrated by illegitimate recombination into random sites in the genome. Sequence analysis of the target sites revealed that for the majority of illegitimate transformants there was no microhomology with the integration site. Approximately 0.25% of the insertions resulted in amino acid auxotrophy, suggesting that insertion was random at a gross level. Sequence analysis suggested that illegitimate recombination is nonrandom at the single-gene level and that the integrating plasmid has a preference for inserting into noncoding regions of the genome. Analysis of the relative numbers of homologous and illegitimate recombination events suggests that C. glabrata possesses efficient systems for both homologous and nonhomologous recombination. (+info)
Characterization of functional residues in the interfacial recognition domain of lecithin cholesterol acyltransferase (LCAT).
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Lecithin cholesterol acyltransferase (LCAT) is an interfacial enzyme active on both high-density (HDL) and low-density lipoproteins (LDL). Threading alignments of LCAT with lipases suggest that residues 50-74 form an interfacial recognition site and this hypothesis was tested by site-directed mutagenesis. The (delta56-68) deletion mutant had no activity on any substrate. Substitution of W61 with F, Y, L or G suggested that an aromatic residue is required for full enzymatic activity. The activity of the W61F and W61Y mutants was retained on HDL but decreased on LDL, possibly owing to impaired accessibility to the LDL lipid substrate. The decreased activity of the single R52A and K53A mutants on HDL and LDL and the severer effect of the double mutation suggested that these conserved residues contribute to the folding of the LCAT lid. The membrane-destabilizing properties of the LCAT 56-68 helical segment were demonstrated using the corresponding synthetic peptide. An M65N-N66M substitution decreased both the fusogenic properties of the peptide and the activity of the mutant enzyme on all substrates. These results suggest that the putative interfacial recognition domain of LCAT plays an important role in regulating the interaction of the enzyme with its organized lipoprotein substrates. (+info)
Development and characterization of complex DNA fingerprinting probes for the infectious yeast Candida dubliniensis.
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Using a strategy to clone large genomic sequences containing repetitive elements from the infectious yeast Candida dubliniensis, the three unrelated sequences Cd1, Cd24, and Cd25, with respective molecular sizes of 15,500, 10,000, and 16,000 bp, were cloned and analyzed for their efficacy as DNA fingerprinting probes. Each generated a complex Southern blot hybridization pattern with endonuclease-digested genomic DNA. Cd1 generated an extremely variable pattern that contained all of the bands of the pattern generated by the repeat element RPS of Candida albicans. We demonstrated that Cd1 does not contain RPS but does contain a repeat element associated with RPS throughout the C. dubliniensis genome. The Cd1 pattern was the least stable over time both in vitro and in vivo and for that reason proved most effective in assessing microevolution. Cd24, which did not exhibit microevolution in vitro, was highly variable in vivo, suggesting in vivo-dependent microevolution. Cd25 was deemed the best probe for broad epidemiological studies, since it was the most stable over time, was the only truly C. dubliniensis-specific probe of the three, generated the most complex pattern, was distributed throughout all C. dubliniensis chromosomes, and separated a worldwide collection of 57 C. dubliniensis isolates into two distinct groups. The presence of a species-specific repetitive element in Cd25 adds weight to the already substantial evidence that C. dubliniensis represents a bona fide species. (+info)
Candidemia at selected Canadian sites: results from the Fungal Disease Registry, 1992-1994. Fungal Disease Registry of the Canadian Infectious Disease Society.
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BACKGROUND: Candida species are important bloodstream pathogens that are being isolated with increasing frequency. Despite the availability of effective antifungal therapy, the mortality rate associated with Candida infection remains high. With the objective of describing the epidemiology of candidemia, the Canadian Infectious Disease Society conducted a study of candidemia in Canada. METHODS: Fourteen medical centres across Canada identified all patients with candidemia from March 1992 to February 1994 through blood culture surveillance for Candida spp. Patient-related data for invasive fungal infection were compiled retrospectively by chart review using a standardized data-recording form developed for the Fungal Disease Registry of the Canadian Infectious Disease Society. Cases of Candidemia were studied in relation to underlying medical conditions, predisposing factors, concurrent infection, antimicrobial agents, antifungal treatment and deaths. RESULTS: In total, 415 cases of candidemia were identified, 48 (11.6%) in children and 367 (88.4%) in adults. The causative pathogens were C. albicans in 286 cases (68.9%), C. parapsilosis in 43 (10.4%), C. glabrata in 34 (8.2%), C. tropicalis in 27 (6.5%) and other Candida species in 18 (4.3%); polymicrobial candidemia occurred in 7 cases (1.7%). The overall mortality rate was 46%, and the rate of deaths clinically related to candidemia was 19%. However, only 13 (27%) of the children died. A univariate analysis indicated that significant risk factors for death were age greater than 60 years, therapy for concomitant bacterial infection, stay in an intensive care unit, concurrent malignant disease, cytotoxic chemotherapy and granulocytopenia, although only age and stay in an intensive care unit emerged as significant risk factors in the multivariate analysis. After adjustment for other predictors of death, only infection with C. parapsilosis was associated with a lower mortality rate than infection with C. albicans. Treatment was given in 352 (84.8%) of cases. Amphotericin B was the preferred agent in 244 cases (69.3% of those treated); fluconazole was used in 101 cases (28.7%) and ketoconazole in 5 cases (1.4%). INTERPRETATION: Candidemia in Canada is caused predominantly by C. albicans. The mortality rate associated with candidemia is high, but it varies with the species of Candida and is lower in children than in adults. Age greater than 60 years and stay in an intensive care unit were the most significant risk factors for overall mortality. (+info)
Candida dubliniensis candidemia in patients with chemotherapy-induced neutropenia and bone marrow transplantation.
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The recently described species Candida dubliniensis has been recovered primarily from superficial oral candidiasis in HIV-infected patients. No clinically documented invasive infections were reported until now in this patient group or in other immunocompromised patients. We report three cases of candidemia due to this newly emerging Candida species in HIV-negative patients with chemotherapy-induced immunosuppression and bone marrow transplantation. (+info)