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Find video protocols related to scientific articles indexed in Pubmed.
Multicentric comparative assessment of the Bio-Evolution® Toxoplasma gondii detection kit with eight laboratory-developed PCR assays for the molecular diagnosis of congenital toxoplasmosis.
J. Clin. Microbiol.
PUBLISHED: 10-24-2014
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Detection of Toxoplasma gondii in amniotic fluid is an essential tool for the prenatal diagnosis of congenital toxoplasmosis and today is essentially based upon PCR. Although some consensus is emerging, this molecular diagnosis suffers from a lack of standardization and an extreme diversity of laboratory-developed methods. Commercial kits for the detection of T. gondii by PCR have been recently developed and offer certain advantages; however they must be assessed in comparison with optimized reference PCR assays. The present multicentric study aimed at comparing the Bio-Evolution® Toxoplasma gondii detection kit with laboratory-developed PCR assays set up in eight proficient centers in France. The study compared 157 amniotic fluid samples and found a concordance of 99% and 100% using 76 T. gondii-infected samples and 81 uninfected samples, respectively. Moreover, taking into account the classification of the European Research Network on Congenital Toxoplasmosis, the overall diagnostic sensitivity of all assays was identical and calculated at 86% (54/63); specificity was 100% for all. Finally, the relative quantification results were in good agreement between the kit and the laboratory-developed assays. The good performances of this commercial kit are probably in part linked to the use of a number of good practices: detection in multiplicate, amplification of the repetitive DNA target 'rep529', use of an internal control for the detection of PCR inhibitors. The only drawbacks noted at the time of the study were the absence of Uracil-N-glycosylase, as well as small defects in the reliability of the production of different reagents.
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Characterization and Multicentric Validation of a Common Standard for Toxoplasma gondii Detection Using Nucleic Acid Amplification Assays.
J. Clin. Microbiol.
PUBLISHED: 09-03-2014
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The molecular diagnosis of toxoplasmosis essentially relies upon laboratory-developed methods and suffers from lack of standardization, hence the large diversity of performances between laboratories. Moreover, quantifications of parasitic loads differ among centers, a fact which prevents the possible prediction of the severity of this disease as a function of parasitic loads. The objectives of this multicentric study performed in eight proficient laboratories of the Molecular Biology Pole of the French National Reference Center for Toxoplasmosis (NRC-T) were (i) to assess the suitability of a lyophilized preparation of Toxoplasma gondii as a common standard for use in this PCR-based molecular diagnosis and (ii) to make this standard available to the community. High-quality written procedures were used for the production and qualification of this standard. Three independent batches of this standard, containing concentrations ranging from 10(4) to 0.01 T. gondii genome equivalents per PCR, were first assessed: the linear dynamic range was ?6 log, the intra-assay coefficients of variation (CV) from a sample containing 10 T. gondii organisms per PCR were 0.3% to 0.42%, and the interassay CV over a 2-week period was 0.76% to 1.47%. A further assessment in eight diagnostic centers showed that the standard is stable, robust, and reliable. These lyophilized standards can easily be produced at a larger scale when needed and can be made widely available at the national level. To our knowledge, this is the first quality control assessment of a common standard which is usable both for self-evaluation in laboratories and for accurate quantification of parasitic loads in T. gondii prenatal infections.
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Pneumocystis jirovecii pneumonia in patients with or without AIDS, France.
Emerging Infect. Dis.
PUBLISHED: 08-23-2014
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Pneumocystis jirovecii pneumonia (PCP) in patients without AIDS is increasingly common. We conducted a prospective cohort study of consecutive patients with proven PCP; of 544 patients, 223 (41%) had AIDS (AIDS patients) and 321 (59%) had other immunosuppressive disorders (non-AIDS patients). Fewer AIDS than non-AIDS patients required intensive care or ventilation, and the rate of hospital deaths--17.4% overall--was significantly lower for AIDS versus non-AIDS patients (4% vs. 27%; p<0.0001). Multivariable analysis showed the odds of hospital death increased with older age, receipt of allogeneic bone marrow transplant, immediate use of oxygen, need for mechanical ventilation, and longer time to treatment; HIV-positive status or receipt of a solid organ transplant decreased odds for death. PCP is more often fatal in non-AIDS patients, but time to diagnosis affects survival and is longer for non-AIDS patients. Clinicians must maintain a high index of suspicion for PCP in immunocompromised patients who do not have AIDS.
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Empirical antifungal therapy with an echinocandin in critically-ill patients: prospective evaluation of a pragmatic Candida score-based strategy in one medical ICU.
BMC Infect. Dis.
PUBLISHED: 07-04-2014
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Invasive candidiasis (IC) is a life-threatening ICU-acquired infection. A strong correlation between time to antifungal therapy (AFT) administration and outcome has been established. Empirical therapy benefit should be balanced with the risk of echinocandin overuse. We assessed therefore a decision rule that aimed at guiding empirical therapy.
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Freezing and storage at -20 °C provides adequate preservation of Toxoplasma gondii DNA for retrospective molecular analysis.
Diagn. Microbiol. Infect. Dis.
PUBLISHED: 04-04-2014
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Nucleic acid-based testing has become crucial for toxoplasmosis diagnosis. For retrospective (forensic or scientific) studies, optimal methods must be employed for DNA long-term storage. We compared Toxoplasma gondii detection before and after DNA storage using real-time PCR. No significant differences were found depending on duration or storage conditions at -20 °C or -80 °C.
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Invasive infections due to Candida norvegensis and Candida inconspicua: report of 12 cases and review of the literature.
Med. Mycol.
PUBLISHED: 07-16-2013
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Candida inconspicua and Candida norvegensis are two closely related species rarely involved in invasive infections. The purpose of this study was to depict the epidemiologic and clinical characteristics of candidemia due to these emerging fluconazole less susceptible species. A retrospective analysis of the epidemiology of C. inconspicua and C. norvegensis during the period 2006-2010 was initiated in six French University hospitals. From this, demographics, clinical, diagnostic and therapeutic data of C. inconspicua or C. norvegensis candidemia were recorded and compared to the observations reported in the literature. C. inconspicua was more frequently isolated compared to C. norvegensis (ratio 2.6) but from the same preferential body sites: mainly digestive (56.4% and 48.37%, respectively, for C. inconspicua and C. norvegensis) and respiratory (26% and 28.2%, respectively). Thirteen cases of candidemia were recorded and five additional cases were found in the literature. Hematogical malignancy was the main underlying disease (n = 12). Associated factors were the presence of a vascular catheter (n = 18), broad-spectrum antibiotics (n = 15), and neutropenia (n = 14). In 13 cases (72%), prior colonization was noted before the candidemia diagnosis. Combining the results for the two species, Minimal Inhibitory Concentrations (MIC50) of amphotericin B, fluconazole, voriconazole and caspofungin were 0.125, 48, 0.25, and 0.19 mg/l, respectively. These two species must be added to the growing list of emerging Candida species poorly susceptible to fluconazole.
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MALDI-TOF mass spectrometry identification of filamentous fungi in the clinical laboratory.
Mycoses
PUBLISHED: 01-23-2013
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This study aimed to validate the effectiveness of a standardised procedure for the MALDI-TOF mass spectrometry (MS)-based identification on a large sample of filamentous fungi routinely identified in university hospitals laboratories. Non-dermatophyte filamentous fungi prospectively isolated in the routine activity of five teaching hospitals in France were first identified by conventional methods in each laboratory and then by MS in one centre. DNA sequence-based identification resolved discrepancies between both methods. In this study, of the 625 analysed filamentous fungi of 58 species, 501 (80%) and 556 (89%) were correctly identified by conventional methods and MS respectively. Compared with the conventional method, MS dramatically enhanced the performance of the identification of the non-Aspergillus filamentous fungi with a 31-61% increase in correct identification rate. In conclusion, this study on a large sample of clinical filamentous fungi taxa demonstrates that species identification is significantly improved by MS compared with the conventional method. The main limitation is that MS identification is possible only if the species is included in the reference spectra library. Nevertheless, for the routine clinical laboratory, MS provides the means to attain markedly accurate results in filamentous fungi identification, which was previously restricted to only a few reference laboratories.
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Rbt1 Protein Domains Analysis in Candida albicans Brings Insights into Hyphal Surface Modifications and Rbt1 Potential Role during Adhesion and Biofilm Formation.
PLoS ONE
PUBLISHED: 01-01-2013
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Cell wall proteins are central to the virulence of Candida albicans. Hwp1, Hwp2 and Rbt1 form a family of hypha-associated cell surface proteins. Hwp1 and Hwp2 have been involved in adhesion and other virulence traits but Rbt1 is still poorly characterized. To assess the role of Rbt1 in the interaction of C. albicans with biotic and abiotic surfaces independently of its morphological state, heterologous expression and promoter swap strategies were applied. The N-terminal domain with features typical of the Flo11 superfamily was found to be essential for adhesiveness to polystyrene through an increase in cell surface hydrophobicity. A 42 amino acid-long domain localized in the central part of the protein was shown to enhance the aggregation function. We demonstrated that a VTTGVVVVT motif within the 42 amino acid domain displayed a high ?-aggregation potential and was responsible for cell-to-cell interactions by promoting the aggregation of hyphae. Finally, we showed through constitutive expression that while Rbt1 was directly accessible to antibodies in hyphae, it was not so in yeast. Similar results were obtained for another cell wall protein, namely Iff8, and suggested that modification of the cell wall structure between yeast and hyphae can regulate the extracellular accessibility of cell wall proteins independently of gene regulation.
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Fusarium species recovered from the water distribution system of a French university hospital.
Int J Hyg Environ Health
PUBLISHED: 04-19-2011
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Dijon Hospital is a French tertiary care institution undergoing major renovation, and different microbiological controls revealed the presence of Fusarium spp. in the water distribution system. Because some Fusarium spp. can cause life-threatening opportunistic infections in immunocompromised patients, an 8-month survey was conducted in two hospital sites in order to evaluate the prevalence of the fungi in the water system. In 2 units of one hospital site, 100% of the samples of tap-water were positive, with high concentrations of Fusarium spp. (up to 10(5)cfu/L). In the second hospital site, 94% of samples were positive, but generally with lower concentrations. The analysis of translation elongation factor 1? (TEF) sequences of 146 isolates revealed the presence of two different Fusarium species: F. oxysporum was detected in all units explored of both hospital sites, and F. dimerum only in one unit of one hospital site. For both species, we suggest that the fungi discovered could be particularly adapted to an aquatic environment.
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From attachment to damage: defined genes of Candida albicans mediate adhesion, invasion and damage during interaction with oral epithelial cells.
PLoS ONE
PUBLISHED: 01-18-2011
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Candida albicans frequently causes superficial infections by invading and damaging epithelial cells, but may also cause systemic infections by penetrating through epithelial barriers. C. albicans is an unusual pathogen because it can invade epithelial cells via two distinct mechanisms: induced endocytosis, analogous to facultative intracellular enteropathogenic bacteria, and active penetration, similar to plant pathogenic fungi. Here we investigated the molecular basis of C. albicans epithelial interactions. By systematically assessing the contributions of defined fungal pathways and factors to different stages of epithelial interactions, we provide an expansive portrait of the processes and activities involved in epithelial infection. We strengthen the concept that hyphal formation is critical for epithelial invasion. Importantly, our data support a model whereby initial epithelial invasion per se does not elicit host damage, but that C. albicans relies on a combination of contact-sensing, directed hyphal extension, active penetration and the expression of novel pathogenicity factors for further inter-epithelial invasion, dissemination and ultimate damage of host cells. Finally, we explore the transcriptional landscape of C. albicans during the early stages of epithelial interaction, and, via genetic analysis, identify ICL1 and PGA34 as novel oral epithelial pathogenicity factors.
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Multicentric comparative analytical performance study for molecular detection of low amounts of Toxoplasma gondii from simulated specimens.
J. Clin. Microbiol.
PUBLISHED: 07-07-2010
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Although screening for maternal toxoplasmic seroconversion during pregnancy is based on immunodiagnostic assays, the diagnosis of clinically relevant toxoplasmosis greatly relies upon molecular methods. A problem is that this molecular diagnosis is subject to variation of performances, mainly due to a large diversity of PCR methods and primers and the lack of standardization. The present multicentric prospective study, involving eight laboratories proficient in the molecular prenatal diagnosis of toxoplasmosis, was a first step toward the harmonization of this diagnosis among university hospitals in France. Its aim was to compare the analytical performances of different PCR protocols used for Toxoplasma detection. Each center extracted the same concentrated Toxoplasma gondii suspension and tested serial dilutions of the DNA using its own assays. Differences in analytical sensitivities were observed between assays, particularly at low parasite concentrations (
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Cellular interactions of Candida albicans with human oral epithelial cells and enterocytes.
Cell. Microbiol.
PUBLISHED: 10-27-2009
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The human pathogenic fungus Candida albicans can cause systemic infections by invading epithelial barriers to gain access to the bloodstream. One of the main reservoirs of C. albicans is the gastrointestinal tract and systemic infections predominantly originate from this niche. In this study, we used scanning electron and fluorescence microscopy, adhesion, invasion and damage assays, fungal mutants and a set of fungal and host cell inhibitors to investigate the interactions of C. albicans with oral epithelial cells and enterocytes. Our data demonstrate that adhesion, invasion and damage by C. albicans depend not only on fungal morphology and activity, but also on the epithelial cell type and the differentiation stage of the epithelial cells, indicating that epithelial cells differ in their susceptibility to the fungus. C. albicans can invade epithelial cells by induced endocytosis and/or active penetration. However, depending on the host cell faced by the fungus, these routes are exploited to a different extent. While invasion into oral cells occurs via both routes, invasion into intestinal cells occurs only via active penetration.
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A prospective survey of air and surface fungal contamination in a medical mycology laboratory at a tertiary care university hospital.
Am J Infect Control
PUBLISHED: 05-15-2009
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Invasive filamentous fungi infections resulting from inhalation of mold conidia pose a major threat in immunocompromised patients. The diagnosis is based on direct smears, cultural symptoms, and culturing fungi. Airborne conidia present in the laboratory environment may cause contamination of cultures, resulting in false-positive diagnosis. Baseline values of fungal contamination in a clinical mycology laboratory have not been determined to date.
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Genotype of 88 Toxoplasma gondii isolates associated with toxoplasmosis in immunocompromised patients and correlation with clinical findings.
J. Infect. Dis.
PUBLISHED: 03-07-2009
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We report the genotyping analysis of Toxoplasma gondii isolates in samples collected from 88 immunocompromised patients, along with clinical and epidemiological data. Most of these samples were collected in France during the current decade by the Toxoplasma Biological Resource Center. Lack of specific anti-Toxoplasma treatment, pulmonary toxoplasmosis, and involvement of multiple organs were the 3 main risk factors associated with death for this patient group. Genotyping results with 6 microsatellite markers showed that type II isolates were predominant among patients who acquired toxoplasmic infection in Europe. Non-type II isolates included 13 different genotypes and were mainly collected from patients who acquired toxoplasmosis outside Europe. Type III was the second most common genotype recovered from patients, whereas type I was rare in our population. Three nonarchetypal genotypes were repeatedly recovered from different patients who acquired the infection in sub-Saharan Africa (genotypes Africa 1 and Africa 2) and in the French West Indies (genotype Caribbean 1). The distribution of genotypes (type II vs. non-type II) was not significantly different when patients were stratified by underlying cause of immunosuppression, site of infection, or outcome. We conclude that in immunocompromised patients, host factors are much more involved than parasite factors in patients resistance or susceptibility to toxoplasmosis.
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Profiles and seasonal distribution of airborne fungi in indoor and outdoor environments at a French hospital.
Sci. Total Environ.
PUBLISHED: 02-06-2009
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A one-year prospective survey of fungal air contamination was conducted in outdoor air and inside two haematological units of a French hospital. Air was sampled with a portable Air System Impactor. During this period of survey, the mean viable fungal load was 122.1 cfu/m(3) in outdoor air samples, and 4.1 and 3.9 cfu/m(3) in samples from adult and pediatric haematology units, respectively. In outdoor samples, Cladosporium was the dominant genus (55%) while in the clinical units, Penicillium sp. (23 to 25%), Aspergillus sp. (15 to 23%) and Bjerkandera adusta (11 to 13%) were the most frequently recovered airborne fungi. The outdoor fungal load was far higher in autumn (168 cfu/m(3)), spring (110 cfu/m(3)) and summer (138 cfu/m(3)) than in winter (49 cfu/m(3)). In indoor air, fungal concentrations were significantly lower in winter (2.7 to 3.1 cfu/m(3)) than in summer (4.2 to 5.0 cfu/m(3)) in both haematology units. In the outdoor environment, Penicillium sp. and Aspergillus sp. were more abundant in winter while the levels of Cladosporium were lowest during this season. In the haematological units, the presence of Aspergillus sp. was stable during the year (close to 20%), Bjerkandera sp. was particularly abundant in winter (close to 30%); levels of Penicillium sp. were highest in autumn while levels of Cladosporium sp. were highest in spring and summer.
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Using a Multi-Locus Microsatellite Typing method improved phylogenetic distribution of Candida albicans isolates but failed to demonstrate association of some genotype with the commensal or clinical origin of the isolates.
Infect. Genet. Evol.
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The dimorphic yeast Candida albicans is a component of the normal microflora at the mucosal surfaces of healthy individuals. It possesses an array of phenotypic properties considered as virulence traits that contribute to pathogenicity of the yeast in immuno-compromised patients. We addressed the question of the pathogenicity of lineages of C. albicans with regard to their genotype in three series of C. albicans isolates (a series of commensal isolates collected in healthy individuals, a group of bloodstream isolates and a group of non-bloodstream clinical isolates) using a Multi-Locus Microsatellite Typing (MLMT) approach based on the analysis of the polymorphism of 11 microsatellite loci. The MLMT analysis of the three series, corresponding to 174 C. albicans isolates, gave a 100% typability to the method, with a DP index of 0.999. The UPGMA analysis showed that the isolates segregated in eight phylogenetic groups. Interestingly, the clustering was comparable when using NJ and MS-tree algorithms and a good concordance index of the clustering was observed with MLST. All in all our data strongly indicated MLMT as a reliable tool for DNA-typing studies in C. albicans. Isolates from healthy and non-healthy individuals segregated at the same proportions into the eight phylogenetic groups, suggesting that isolates of different origin share the same overall pathogenicity. Surprisingly allelic frequencies at the HIS3 microsatellite differed significantly in commensal isolates (group A) from pooled groups B and C (clinical isolates), raising the possibility that some individual alleles at the HIS3 microsatellite may be associated with distinct pathogenic profiles in C. albicans.
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Interleukin 17A as an effective target for anti-inflammatory and antiparasitic treatment of toxoplasmic uveitis.
J. Infect. Dis.
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Toxoplasmosis is the most common cause of posterior uveitis in immunocompetent subjects. The requirement of limiting both parasite multiplication and tissue destruction suggests that the balance between T-helper (Th) 17 and T-regulatory cells is an important factor in toxoplasmosis-induced retinal damage.
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Optimization of the preanalytical steps of matrix-assisted laser desorption ionization-time of flight mass spectrometry identification provides a flexible and efficient tool for identification of clinical yeast isolates in medical laboratories.
J. Clin. Microbiol.
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We report here that modifications of the preanalytical steps of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) identification of yeasts, with regard to the original protocol provided by the manufacturers, appear to be efficient for the reliable routine identification of clinical yeast isolates in medical laboratories. Indeed, when one colony was sampled instead of five and the protein extraction protocol was modified, the performance of MALDI-TOF MS was superior to that of the API ID 32C method (discrepancies were confirmed by using molecular identification), allowing the correct identification of 94% of the 335 clinical isolates prospectively tested. We then demonstrated that the time for which the primary cultures were preincubated on CHROMagar did not impact the identification of yeasts by MALDI-TOF MS, since 95.1 and 96.2% of the 183 clinical yeast isolates prospectively tested were correctly identified after 48 and 72 h of preincubation, respectively.
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Evaluation of MALDI-TOF mass spectrometry for the identification of medically-important yeasts in the clinical laboratories of Dijon and Lille hospitals.
Med. Mycol.
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Conventional identification (CI) of yeasts is based on morphological, biochemical and/or immunological methods. Matrix-assisted laser desorption/ionization - time of flight (MALDI-TOF or MT-MS) mass spectrometry has been proposed as a new method for the identification of microorganisms. This prospective study compared the performance of MT-MS and CI for the identification of yeasts isolated from clinical samples. Sequencing of the internal transcribed spacer (ITS) regions of ribosomal DNA was used as the reference method in the analysis of a total of 1207 yeast isolates. Concordance between MT-MS and CI was observed for 1105 isolates (91.5%), while 74 isolates (6.1%) were misidentified. Molecular identification revealed that 73 of these 74 isolates were identified correctly by MT-MS and CI correctly identified the last one. Concordance between the two techniques was excellent for the medically-important species (98-100%), including the identification of closely-related species (Candida albicans/C. dubliniensis; C. inconspicua/C. norvegensis; C. parapsilosis/C. metapsilosis/C. orthopsilosis). Only 2.3% of isolates belonging to C. famata, C. lambica and C. magnoliae or to Geotrichum spp. and Trichosporon spp. were not identified by MT-MS. This investigation highlights the potential of MT-MS-based yeast identification as a reliable, time and cost-efficient alternative to CI.
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Candida spp. airway colonization could promote antibiotic-resistant bacteria selection in patients with suspected ventilator-associated pneumonia.
Intensive Care Med
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Candida spp. airway colonization could promote development of ventilator-associated pneumonia (VAP) caused by Pseudomonas aeruginosa, a potentially multidrug-resistant (MDR) bacteria, and worsen the outcome of VAP regardless of pathogen. We therefore address the question of the risk of MDR bacteria isolation within the airway of patients with suspected VAP, whether Candida spp. is present or not.
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Candida albicans-epithelial interactions: dissecting the roles of active penetration, induced endocytosis and host factors on the infection process.
PLoS ONE
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Candida albicans frequently causes superficial infections by invading and damaging epithelial cells, but may also cause systemic infections by penetrating through epithelial barriers. C. albicans is a remarkable pathogen because it can invade epithelial cells via two distinct mechanisms: induced endocytosis, analogous to facultative intracellular enteropathogenic bacteria, and active penetration, similar to plant pathogenic fungi. Here we investigated the contributions of the two invasion routes of C. albicans to epithelial invasion. Using selective cellular inhibition approaches and differential fluorescence microscopy, we demonstrate that induced endocytosis contributes considerably to the early time points of invasion, while active penetration represents the dominant epithelial invasion route. Although induced endocytosis depends mainly on Als3-E-cadherin interactions, we observed E-cadherin independent induced endocytosis. Finally, we provide evidence of a protective role for serum factors in oral infection: human serum strongly inhibited C. albicans adhesion to, invasion and damage of oral epithelial cells.
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JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

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In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.