283 research outputs found
Dormancy in Cryptococcus neoformans: 60 years of accumulating evidence
No full textInternational audienceCryptococcus neoformans is an opportunistic yeast that is present worldwide and interacts with various organisms. In humans, it is responsible for cryptococcosis, a deadly invasive fungal infection that represents around 220,000 cases per year worldwide. Starting from the natural history of the disease in humans, there is accumulating evidence on the capacity of this organism to enter dormancy. In response to the harsh host environment, the yeast is able to adapt dramatically and escape the vigilance of the host's immune cells to survive. Indeed, the yeast exposed to the host takes on pleiotropic phenotypes, enabling the generation of populations in heterogeneous states, including dormancy, to eventually survive at low metabolic cost and revive in favorable conditions. The concept of dormancy has been validated in C. neoformans from both epidemiological and genotyping data, and more recently from the biological point of view with the characterization of dormancy through the description of viable but nonculturable cells
Difficulties with molecular diagnostic tests for mould and yeast infections: where do we stand?
No full textInternational audiencePCR assays have not reached the same level of acceptance for the detection of human fungal pathogens as for other micro-organisms, mainly because the low number of micro-organisms challenges the detection limits of PCR. Therefore, whereas meta-analyses focusing on clinical validation suggest interest in adding PCR results to the diagnostic workup for invasive fungal disease (IFD) along with clinical evaluation, CT scans, classical mycology and antigen detection, no consensual PCR method has emerged. Compared with the end-point format of the 1990s, real-time quantitative PCR is a major breakthrough. This format prevents contamination with previously amplified products, provides the yield of amplification, allows for developing consensus procedures and should therefore be the only format used. An internal control is now mandatory to avoid false-negative results. Primer design strongly impacts on the objectives: pan-fungal primers can provide false-positive results due to environmental fungal DNA contamination; conversely, species-specific primers miss infections caused by untargeted fungi. Unresolved issues include the best specimens to be used; serum is currently preferred to blood because of the ease of the DNA extraction step. Work is in progress to establish standards at least for Aspergillus PCR, and the implementation of quality controls should help centres to improve assays. Eventually, the classical analysis of biomarker performance does not consider the evolving risk factors and changing treatments during IFD, which can lead to variable conclusions. New statistical methods such as event history analysis should be considered
Performance evaluation of multiplex PCR including Aspergillus-not so simple!
No full textInternational audienceMultiplex PCRs have been designed for including species other than Aspergillus fumigatus for the diagnosis of invasive aspergillosis, such as microarrays, liquid-phase array, and electrospray-ionization mass spectrometry (PCR/ESI MS). These methods are based on the selection of multiple primers to amplify different species with the specificity checked by hybridization to a probe or by base composition of the amplicon for the PCR/ESI MS. When testing complex samples such as respiratory specimens, some clinically relevant species can be missed. Indeed, it is impossible to design primers able to amplify all the known fungal species with the same efficiency. Therefore, the best amplified species may not be the most clinically relevant. Multiplex assays have also been proposed to detect A. fumigatus DNA and azole resistance. Since the gene responsible for azole resistance is single copy and the gene used for detection is multicopy, only the high fungal loads can be evaluated. Thus, although interesting for investigating mycobiome, the multiplex assays should be used with cautious for the diagnosis of IA or the detection of resistance. For the diagnosis of invasive aspergillosis, validated quantitative PCRs specifically targeting A. fumigatus or a limited set of species to increase sensitivity is a safer option
Faculty Opinions recommendation of Typing of Pneumocystis jirovecii by multilocus sequencing: evidence of outbreak?
No full textFaculty Opinions recommendation of Pneumocystis jirovecii pneumonia in patients with or without AIDS, France.
No full textFaculty Opinions recommendation of Epidemiological Outbreaks of Pneumocystis jirovecii Pneumonia Are Not Limited to Kidney Transplant Recipients: Genotyping Confirms Common Source of Transmission in a Liver Transplantation Unit.
No full textFaculty Opinions recommendation of Systematic review of outbreaks of Pneumocystis jirovecii pneumonia: evidence that P. jirovecii is a transmissible organism and the implications for healthcare infection control.
No full textFaculty Opinions recommendation of Genome analysis of three Pneumocystis species reveals adaptation mechanisms to life exclusively in mammalian hosts.
No full textFaculty Opinions recommendation of Comparative genomics of pneumocystis species suggests the absence of genes for myo-inositol synthesis and reliance on inositol transport and metabolism.
No full textFaculty Opinions recommendation of Pneumocystis pneumonia associated with human immunodeficiency virus infection without elevated (1 → 3)-β-D glucan: A case report.
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