Delayed-Onset Hemolytic Anemia in Patients with Travel-Associated Severe Malaria Treated with Artesunate, France, 2011–2013

French Artesunate Working GroupInternational audienceArtesunate is the most effective treatment for severe malaria. However, delayed-onset hemolytic anemia has been observed in ≈20% of travelers who receive artesunate, ≈60% of whom require transfusion. This finding could discourage physicians from using artesunate. We prospectively evaluated a cohort of 123 patients in France who had severe imported malaria that was treated with artesunate; our evaluation focused on outcome, adverse events, and postartesunate delayed-onset hemolysis (PADH). Of the 123 patients, 6 (5%) died. Overall, 97 adverse events occurred. Among the 78 patients who received follow-up for >8 days after treatment initiation, 76 (97%) had anemia, and 21 (27%) of the 78 cases were recorded as PADH. The median drop in hemoglobin levels was 1.3 g/dL; 15% of patients with PADH had hemoglobin levels of <7 g/dL, and 1 required transfusion. Despite the high incidence of PADH, the resulting anemia remained mild in 85% of cases. This reassuring result confirms the safety and therapeutic benefit of artesunate

Candida glabrata (pathogène fongique émergent)

Candida glabrata est le second agent étiologique des candidoses de l'adulte. Nous avons développé une PCR pour le différentier de C. bracarensis et C. nivariensis deux espèces phénotypiquement identiques. Le développement d une méthode de typage par microsatellites, nous a permis de montrer une répartition des souches principalement au sein de six complexes clonaux, l un ne comportant que des souches MATa. La méthode a été validée pour le traçage des souches. L analyse des génotypes de souches isolées du tube digestif humain et d hémocultures a montré que C. glabrata pouvait micro-évoluer au niveau du tube digestif, qu une transmission intrafamiliale existait et que les souches digestives présentaient une diversité génétique plus importante. Celle-ci a été aussi retrouvée par l analyse du polymorphisme de taille des gènes EPA. Nous avons étudié comparativement l adhésion in vitro sur cellules Caco2, de souches présentant des génotypes différents. Le niveau d adhésion n était pas corrélé aux caractéristiques génétiques mais il existait d importantes variations selon les souches. Ces résultats devraient être utiles pour des études ultérieuresPARIS-BIUSJ-Biologie recherche (751052107) / SudocSudocFranceF

Neospora caninum (à propos d'une étude sérologique chez des patients infectés par le VIH)

PARIS6-Bibl. St Antoine CHU (751122104) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Genome editing in the yeast Nakaseomyces delphensis and description of its complete sexual cycle

The environmental yeast Nakaseomyces delphensis is, phylogenetically, the closest known species to Candida glabrata, a major fungal pathogen of humans. C. glabrata is haploid and described as asexual, while N. delphensis is also haploid, but has been described as competent for mating and meiosis. Both genomes contain homologs of all the genes necessary for sexual reproduction, and also the genes for Ho-dependent mating-type switching, like Saccharomyces cerevisiae. We first report the construction of genetically-engineered strains of N. delphensis, including by CRISPR-Cas 9 gene-editing. We also report the description of the sexual cycle of N. delphensis. We show that it undergoes Ho-dependent mating-type switching in culture, and that deletion of the HO gene prevents such switching and allows maintenance of stable, separate, MATa and MATalpha haploid strains. Rare, genetically selected diploids can be obtained through mating of haploid strains, mutated or not for the HO gene. In contrast to HO/HO diploids, which behave as expected, Δho/Δho diploids exhibit unusual profiles in flow-cytometry. Both types of diploids can produce recombined haploid cells, which grow like the original haploid type strain. Our experiments thus allow the genetic manipulation of N. delphensis and the reconstruction, in the laboratory, of its entire life-cycle

Rapid diagnosis of cryptococcosis using an antigen detection immunochromatographic test.

International audienceCurrent methods for cryptococcal antigen detection have some limitations. This study aimed at evaluating a lateral flow assay (LFA) for the diagnosis of cryptococcosis in a French University medical center. A retrospective study was performed on samples collected from patients with a definitive diagnosis of cryptococcosis (group I 66 samples; 28 patients) or with non-Cryptococcus invasive fungal infection (group II 18 samples; 17 patients). In addition, 274 samples from 205 consecutive patients, either suspected of cryptococcal infection or routinely screened during their follow-up, were prospectively tested (group III). Cryptococcal antigen was assayed using LFA and an EIA. A latex-based test was used for confirmation. Sensitivity calculated on group I and specificity on group II, were respectively at 100% and 90.0%. Two false positives were related to Trichosporon fungemia. Per-sample analysis on group III revealed sensitivity, specificity, positive and negative predictive values all at 100% for CSF, and at 100%, 98.9%, 75% and 100%, respectively for serum samples. LFA enabled the diagnosis of two cases of asymptomatic cryptococcosis. The excellent diagnostic value and practicality (visual reading results in 15 min) of LFA make it fully appropriate for the diagnosis of cryptococcosis in this particular setting

Efficient Mating-Type Switching in Candida glabrata Induces Cell Death.

Candida glabrata is an apparently asexual haploid yeast that is phylogenetically closer to Saccharomyces cerevisiae than to Candida albicans. Its genome contains three MAT-like cassettes, MAT, which encodes either MATa or MATalpha information in different strains, and the additional loci, HML and HMR. The genome also contains an HO gene homolog, but this yeast has never been shown to switch mating-types spontaneously, as S. cerevisiae does. We have recently sequenced the genomes of the five species that, together with C. glabrata, make up the Nakaseomyces clade. All contain MAT-like cassettes and an HO gene homolog. In this work, we express the HO gene of all Nakaseomyces and of S. cerevisiae in C. glabrata. All can induce mating-type switching, but, despite the larger phylogenetic distance, the most efficient endonuclease is the one from S. cerevisiae. Efficient mating-type switching in C. glabrata is accompanied by a high cell mortality, and sometimes results in conversion of the additional cassette HML. Mortality probably results from the cutting of the HO recognition sites that are present, in HML and possibly HMR, contrary to what happens naturally in S. cerevisiae. This has implications in the life-cycle of C. glabrata, as we show that efficient MAT switching is lethal for most cells, induces chromosomal rearrangements in survivors, and that the endogenous HO is probably rarely active indeed

Functional networks of co-expressed genes to explore iron homeostasis processes in the pathogenic yeast Candida glabrata

International audienceCandida glabrata is a cause of life-threatening invasive infections especially in elderly and immunocompromised patients. Part of human digestive and urogenital microbiota, C. glabrata faces varying iron availability, low during infection or high in digestive and urogenital tracts. To maintain its homeostasis, C. glabrata must get enough iron for essential cellular processes and resist toxic iron excess. The response of this pathogen to both depletion and lethal excess of iron at 30 • C have been described in the literature using different strains and iron sources. However, adaptation to iron variations at 37 • C, the human body temperature and to gentle overload, is poorly known. In this study, we performed transcriptomic experiments at 30 • C and 37 • C with low and high but sub-lethal ferrous concentrations. We identified iron responsive genes and clarified the potential effect of temperature on iron homeostasis. Our exploration of the datasets was facilitated by the inference of functional networks of co-expressed genes, which can be accessed through a web interface. Relying on stringent selection and independently of existing knowledge, we characterized a list of 214 genes as key elements of C. glabrata iron homeostasis and interesting candidates for medical applications

Genome Comparisons of Candida glabrata Serial Clinical Isolates Reveal Patterns of Genetic Variation in Infecting Clonal Populations

Candida glabrata is an opportunistic fungal pathogen that currently ranks as the second most common cause of candidiasis. Although the mechanisms underlying virulence and drug resistance in C. glabrata are now starting to be elucidated, we still lack a good understanding of how this yeast adapts during the course of an infection. Outstanding questions are whether the observed genomic plasticity of C. glabrata plays a role during infection, or what levels of genetic variation exist within an infecting clonal population. To shed light onto the genomic variation within infecting C. glabrata populations, we compared the genomes of 11 pairs and one trio of serial clinical isolates, each obtained from a single patient. Our results provide a catalog of genetic variations existing within clonal infecting isolates, and reveal an enrichment of non-synonymous changes in genes encoding cell-wall proteins. Genetic variation and the presence of non-synonymous mutations and copy number variations accumulated within the host, suggest that clonal populations entail a non-negligible level of genetic variation that may reflect selection processes that occur within the human body. As we show here, these genomic changes can underlie phenotypic differences in traits that are relevant for infection.TG group acknowledges support from the Spanish Ministry of Economy, Industry, and Competitiveness (MEIC) for the EMBL partnership, and grants “Centro de Excelencia Severo Ochoa 2013–2017” SEV-2012-0208, and BFU2015-67107 cofunded by European Regional Development Fund (ERDF), from the CERCA Programme/Generalitat de Catalunya; from the Catalan Research Agency (AGAUR) SGR857, and grant from the European Union’s Horizon 2020 research and innovation programme under the grant agreement ERC-2016-724173 the Marie Sklodowska-Curie grant agreement No. H2020-MSCA-ITN-2014-642095. This project received support from the INB Grant (PT17/0009/0023 – ISCIII-SGEFI/ERDF)

Enterocytozoon bieneusi Microsporidiosis in Stem Cell Transplant Recipients Treated with Fumagillin

International audienceEnterocytozoon bieneusi microsporidiosis is an emerging disease in immunocompromised patients. We report 2 cases of this disease in allogeneic hematopoietic stem cell transplant patients successfully treated with fumagillin. Thrombocytopenia occurred but without major adverse events. Modifications of immunosuppression could be avoided when E. bieneusi is rapidly identified and fumagillin therapy is started promptly

A Mouse Model for <i>Candida glabrata</i> Hematogenous Disseminated Infection Starting from the Gut: Evaluation of Strains with Different Adhesion Properties

<div><p>Adhesion to digestive mucosa is considered a crucial first step in the pathogenicity of invasive <i>Candida</i> infections. <i>Candida glabrata</i> disseminated infections predominantly start from the gut. A mouse model of disseminated infection starting from the gut was set up. Hematogenous dissemination was obtained after a low-protein diet followed by a regimen of cyclophosphamide-methotrexate and an oral inoculation of the yeasts via the drinking water. The liver was the first organ infected (day 7 post-infection), and lethality was 100% at day 21 post-infection. This new mouse model was used to compare the mortality rate and fungal burden in deep organs induced by 5 strains exhibiting different levels of adhesion to enterocyte Caco-2 cells, as determined in a test on 36 <i>C. glabrata</i> strains. In this model, no statistical difference of lethality was demonstrated between the strains, and fungal burden varied in kidneys and lungs but without correlation with the level of adhesion to enterocytes. Further studies using the model developed here allow analysis of the crossing of the digestive mucosa by yeasts, and help relate this to yet-poorly understood adhesion phenotypes.</p></div