Biomedical subjects

Sonia Brena

Publications and source records attributed to Sonia Brena.

5 recordsLinked to original sources

PubMed2006

Use of DNA microarray technology and gene expression profiles to investigate the pathogenesis, cell biology, antifungal susceptibility and diagnosis of Candida albicans.

The use of DNA microarrays is becoming the method of choice for assaying gene expression, particularly as costs and complexity are being reduced as the technology becomes more widespread and better standardized. A DNA array is nothing but a collection of probes fixed on a solid support. The probes can be PCR products of ORFs or short intragenic oligonucleotides deposited or synthesized in situ by photolithographic methods. To date, sequencing projects for fungal genomes have yielded 10 complete genomes and 21 whole shotgun sequences, including Candida albicans strain SC5314. Sequencing of the C. albicans genome has led to the construction of whole-genome DNA microarrays for in vitro transcription profiling by several universities and companies. The use of microarray or DNA chip techniques for Candida research has started recently but the number of studies using this technology is increasing rapidly, in order to address important remaining questions about pathogenesis, cell biology, antifungal susceptibility, and diagnosis.

Antifungal Agents↗

PubMed2004

Typing fungal isolates: molecular methods and computerized analysis.

Infections caused by fungi (mycoses) are increasingly reported in many countries owing to greater life expectancy associated with an increase in quality of medical and surgical procedures, as well as the emergence of diseases or infections that affect the immune system such as AIDS. Nosocomial outbreaks of fungal infections are sometimes reported, and typing is then necessary to find the reservoirs, analyze the modes of transmission, study the antifungal susceptibility patterns, and investigate the susceptibility of the host. In addition, the food industry is increasingly demanding typing methods that could help in selection of the best fungal strains, in order to incorporate them in the productive chains and augment the quality and security of food. This is the case for Saccharomyces cerevisiae in the wine industry: the selection and characterization of indigenous or autochthonous strains is an important objective for the production of high-quality certified wines.Several genotyping methods are now widely used for strain delineation of medically or economically important microorganisms belonging to the kingdom Fungi. Most molecular typing methods are comparable to those already described for bacteria, although the peculiarities of their nucleic acids increase the number of available methods. Although typing procedures based on the analysis of nucleic acid sequences have been developed, most genotyping methods currently in use are electrophoretically based, and the procedures include the visual comparison of nucleic acid band profiles or their reading with the help of computerized software. Here we describe some of the most frequently used genotyping methods for fungi, based on polymerase chain reactions (PCR), the isolation of chromosomal or mitochondrial DNA, and their restriction using endonuclease enzymes. The latter methods are exclusive for typing eukaryotic organisms and are based on the expected polymorphism obtained from the separation of large chromosomes using pulsed-field gel electrophoresis (PFGE) and the restriction of mitochondrial or chromosomal DNA. More sophisticated methods, such as those that combine endonuclease restriction with hybridization, are also available, although their use is less extensive and is limited mostly to research laboratories.

Base Sequence↗

PubMed2004

[Genotypes of Candida dubliniensis in clinical isolates].

Amplification of specific sequences of the ITS1 and ITS2 regions and the intervening 5.8S rRNA gene has lead to the identification of four separate genotypes in Candida dubliniensis. Using primers specific for each genotype, we have studied the prevalence of these genotypes among 68 clinical isolates, mostly from Spanish patients infected by HIV. The majority of the isolates tested belonged to genotype 1 (97%), while only one isolate each from genotypes 2 (1.5%) and 3 (1.5%) were detected in the oral cavity of two patients with HIV infection.

Candida↗

PubMed2004

In-vitro activity of 5-fluorocytosine against 1,021 Spanish clinical isolates of Candida and other medically important yeasts.

The aim of this study was to determine the prevalence of primary resistance to 5-fluorocytosine (5FC) among clinical isolates of yeasts in Spain where this drug is not currently available for therapy. We have tested the in vitro activity of 5FC against 1,021 recent yeast clinical isolates, including 522 Candida albicans, 140 Candida parapsilosis, 68 Candida glabrata, 41 Candida dubliniensis, 50 Candida guilliermondii, 34 Candida tropicalis, 28 Candida krusei, 20 Candida famata, 11 Cryptococcus neoformans, 5 Cryptococcus albidus, 43 Rhodotorula spp., 24 Trichosporon spp., 5 Saccharomyces cerevisiae, 9 Pichia spp., and 21 isolates from other 11 yeast species. The MICs were determined by the ATB Fungus agar microdilution test (bioMerieux, France) and the following interpretive breakpoints were used: susceptible, > 4 microg/ml; intermediate, 8 to 16 microg/ml; resistant, > 32 microg/ml. 5FC was very active against Candida spp. and other medically important yeasts as 852 (83.4%) of the studied isolates were susceptible (MIC < 4 microg/ml). The species most susceptible to 5FC were C. dubliniensis (100%of isolates; MIC90, 0.25 microg/ml), C. famata (100% of isolates; MIC90, 0.25 microg/ml), C. guilliermondii (98%of isolates; MIC90, 0.25 microg/ml), C. glabrata (95.5% of isolates; MIC90, 0.25 microg/ml), and C. neoformans (90.9% of isolates; MIC90, 2 microg/ml). Primary resistance to 5FC was very uncommon, and a MIC > 32 microg/ml, indicator of in vitro resistance, was observed in 106 isolates (10.4%): 77 C. albicans (16.5% of isolates; MIC90, > 128 microg/ml), 9 C. parapsilosis (6.4% of isolates; MIC90, 8 microg/ml), 4 C. albidus (80% of isolates, MIC50, > 128 microg/ml), 3 C. glabrata (4.4% of isolates; MIC90, 0.25 microg/ml), 3 C. tropicalis (8.8% of isolates; MIC90, 4 microg/ml), 2 C. krusei (7.1% of isolates; MIC90, 8 microg/ml), 2 Rhodotorula spp. (4.6% of isolates, MIC90, 1 microg/ml), 8 Trichosporon spp. (33.3% of isolates; MIC90, 64 microg/ml), and 1 C. lipolytica (50% of isolates). Interestingly, most C. albicans (67 out of 77 isolates) resistant to 5FC were serotype B isolates.

Antifungal Agents↗

PubMedDate not supplied

Isolation of Candida dubliniensis in a teenager with denture stomatitis.

OBJECTIVES: Test several methods that allow the differentiation between Candida albicans and Candida dubliniensis, in an attempt to assess whether C. dubliniensis can be recovered from the oral cavity of teenagers wearing orthopedic oral prostheses. MATERIAL AND METHODS: Twelve Candida strains were isolated from the prosthesis as well as the palatal mucosa in contact with the dental prosthesis from 12 teenager patients wearing orthopedic oral prostheses. Differentiation between C. albicans and C. dubliniensis was achieved by a number of phenotypic tests (carbon assimilation by the commercially available ID 32C test, growth at 45 grades C on Sabouraud glucose agar, abundant chlamydospore production on Casein agar, and reactivity with a C. dubliniensis antiserum) and the polymerase chain reaction (PCR). Serotyping of C. albicans was performed with monoclonal antibody B9E. RESULTS: All 12 patients studied presented a Newton s type 2 denture stomatitis and in every patient the same Candida species were isolated from the prosthesis and the palatal mucosa in contact with the dental prosthesis. CHROMagar Candida and the germ tube test allowed the differentiation of isolates giving green colonies and a positive germ tube test from those giving violet colonies and a negative germ tube test. Only the isolate from patient 8 was stained by the C. dubliniensis antiserum and showed abundant chlamydospore production on Casein agar. Eight isolates did not grow at 45 grades C. Identification of all isolates was obtained by the ID 32C test. C. albicans was identified in 75% of patients, C. glabrata in 16,6% and C. dubliniensis in 8,3%. By using specific primers for typing C. dubliniensis, PCR allowed the identification of patient s 8 isolate as C. dubliniensis genotype 1. CONCLUSION: C. dubliniensis can be isolated from the oral cavity of teenagers wearing orthopedic oral prostheses and it is possible and technically amenable, the differentiation between C. albicans y C. dubliniensis using the ID 32C test, the observation of abundant chlamydospore production on Casein agar, the reactivity with a C. dubliniensis antiserum and the PCR.

Adolescent↗